Nitrogen(N)doping has been widely adopted to improve the light absorption of TiO_(2).However,the newly introduced N-2p states are largely localized thus barely overlap with O-2p states in the valence band of TiO_(2),r...Nitrogen(N)doping has been widely adopted to improve the light absorption of TiO_(2).However,the newly introduced N-2p states are largely localized thus barely overlap with O-2p states in the valence band of TiO_(2),resulting in a shoulder-like absorption edge.To realize an apparent overlap between N-2p and O-2p states,charge compensation between N^(3-)and O^(2-)via electron transfer from oxygen vacancies(VO)to N dopants is one possible strategy.To verify this,in numerous doping configurations of N/VO-codoped anatase TiO_(2),we identified two types of VOposition independent N-dopant spatial orderings by efficient screening enabled with a newly designed structural descriptor.Compared with others,these two types of the N-dopant spatial orderings are highly beneficial for charge compensation to produce an apparent overlap between N-2p and O-2p states,therefore achieving a large bandgap narrowing.Furthermore,the two types of the N-dopant spatial orderings can also be generalized to N/VO-codoped rutile TiO_(2)for bandgap narrowing.展开更多
A new layered Cu-based oxychalcogenide Ba_3Fe_2O_5Cu_2S_2 has been synthesized and its magnetic and electronic properties were revealed. Ba_3Fe_2O_5Cu_2S_2 is built up by alternatively stacking [Cu_2S_2]^（2-） layers...A new layered Cu-based oxychalcogenide Ba_3Fe_2O_5Cu_2S_2 has been synthesized and its magnetic and electronic properties were revealed. Ba_3Fe_2O_5Cu_2S_2 is built up by alternatively stacking [Cu_2S_2]^（2-） layers and iron perovskite oxide[（FeO_2）（BaO）（FeO_2）]^（2-）layers along the c axis that are separated by barium ions with Fe^（3＋） fivefold coordinated by a square-pyramidal arrangement of oxygen. From the bond valence arguments, we inferred that in layered CuC h-based（Ch =S, Se, Te） compounds the ＋3 cation in perovskite oxide sheet prefers a square pyramidal site, while the lower valence cation prefers the square planar sites. The studies on susceptibility, transport, and optical reflectivity indicate that Ba_3Fe_2O_5Cu_2S_2 is an antiferromagnetic semiconductor with a Ne′el temperature of 121 K and an optical bandgap of 1.03 eV. The measurement of heat capacity from 10 K to room temperature shows no anomaly at 121 K. The Debye temperature is determined to be 113 K. Theoretical calculations indicate that the conduction band minimum is predominantly contributed by O 2p and 3 d states of Fe ions that antiferromagnetically arranged in FeO_2 layers. The Fe 3d states are located at lower energy and result in a narrow bandgap in comparison with that of the isostructural Sr_3Sc_2O_5Cu_2S_2.展开更多
Organic-inorganic hybrid solar cells consisting of organic conjugated materials and inorganic quantum dots(QDs)have been of great interest during the past two decades.However,it is still challenging to select desired ...Organic-inorganic hybrid solar cells consisting of organic conjugated materials and inorganic quantum dots(QDs)have been of great interest during the past two decades.However,it is still challenging to select desired organic functional materials for fabricating hybrid films to maximize their photovoltaic performance.Herein,we report the synthesis of three narrow bandgap non-fullerene conjugated polymers and further demonstrate the importance and impact of polymer crystallinity in tuning the organic-inorganic hybrid interface towards improved photovoltaic performance.In specific,we develop an organic-inorganic hybrid active layer using a newly synthesized polymer with relatively weaker crystallinity and FAPbI_(3)QDs,enabling complementary absorption and favorable interface/morphology for efficient charge separation and transport.The champion PCDOT-T/FAPbI_(3)QD hybrid device achieves a record-high efficiency of 13.11%based on the one-step coating organic/QD hybrid bulk heterojunction blend,which is significantly improved relative to the semi-crystalline polymer PYIT-based hybrid device(11.23%)and pristine QD(10.51%).We believe these findings would provide new insight into the organic/QD interface to construct desired hybrid films for high-performing optoelectronic applications.展开更多
Heavy doping of the base in HBTs brings about a bandgap narrowing （BGN） effect, which modifies the intrinsic carrier density and disturbs the band offset, and thus leads to the change of the currents. Based on a the...Heavy doping of the base in HBTs brings about a bandgap narrowing （BGN） effect, which modifies the intrinsic carrier density and disturbs the band offset, and thus leads to the change of the currents. Based on a thermionic-field-diffusion model that is used to the analyze the performance of an abrupt HBT with a heavydoped base, the conclusion is made that, although the BGN effect makes the currents obviously change due to the modification of the intrinsic carrier density, the band offsets disturbed by the BGN effect should also be taken into account in the analysis of the electrical characteristics of abrupt HBTs. In addition, the BGN effect changes the bias voltage for the onset of Kirk effects.展开更多
Photocatalytic water splitting, which directly converts solar energy into hydrogen, is one of the most desirable solar-energy-conversion approaches. The ultimate target of photocatalysis is to explore efficient and st...Photocatalytic water splitting, which directly converts solar energy into hydrogen, is one of the most desirable solar-energy-conversion approaches. The ultimate target of photocatalysis is to explore efficient and stable photocatalysts for solar water splitting. Tantalum （oxy）nitride-based materials are a class of the most promising photocatalysts for solar water splitting because of their narrow bandgaps and sufficient band energy potentials for water splitting. Tantalum （oxy）nitride-based photocatalysts have experienced intensive exploration, and encouraging progress has been achieved over the past years. However, the solar- to-hydrogen （STH） conversion efficiency is still very far from its theoretical value. The question of how to better design these materials in order to further improve their water-splitting capability is of interest and importance. This review summarizes the development of tantalum （oxy）nitride-based photocatalysts for solar water spitting. Special interest is paid to important strategies for improving photocatalytic water- splitting efficiency. This paper also proposes future trends to explore in the research area of tantalum-based narrow bandgap photocatalysts for solar water splitting.展开更多
To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reporte...To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H_(2) generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H_(2) under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H_(2) generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(N_(D))in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.展开更多
Improving the performance and reducing the manufacturing costs are the main directions for the development of organic solar cells in the future.Here,the strategy that uses chemical structure modification to optimize t...Improving the performance and reducing the manufacturing costs are the main directions for the development of organic solar cells in the future.Here,the strategy that uses chemical structure modification to optimize the photoelectric properties is reported.A new narrow bandgap(1.30 eV)chlorinated non-fullerene electron acceptor(Y15),based on benzo[d][1,2,3] triazole with two 3-undecylthieno[2’,3’:4,5] thieno[3,2-b] pyrrole fused-7-heterocyclic ring,with absorption edge extending to the near-infrared(NIR) region,namely A-DA’D-A type structure,is designed and synthesized.Its electrochemical and optoelectronic properties are systematically investigated.Benefitting from its NIR light harvesting,the fabricated photovoltaic devices based on Y15 deliver a high power conversion efficiency(PCE) of 14.13%,when blending with a wide bandgap polymer donor PM6.Our results show that the A-DA’D-A type molecular design and application of near-infrared electron acceptors have the potential to further improve the PCE of polymer solar cells(PSCs).展开更多
Two acceptor-donor-acceptor(A-D-A)type non-fullerene acceptors(namely WH1 and WH7)containing the oxindole-based bridge are designed and synthesized for polymer solar cells(PSCs)applications.The bridge unit is introduc...Two acceptor-donor-acceptor(A-D-A)type non-fullerene acceptors(namely WH1 and WH7)containing the oxindole-based bridge are designed and synthesized for polymer solar cells(PSCs)applications.The bridge unit is introduced through a precursor(6-bromo-1-octylindoline-2,3-dione)that contains both bromine and carbonyl and provides the feasibility of the Pd-catalyzed cross-coupling reaction and the Knoevenagel condensation,respectively.This facile synthetic approach exhibits the potential to gain high performance non-fullerene acceptors through extendingπ-conjugated backbone with strong light-absorbing building blocks.The synthesis and properties of WH1 and WH7 are demonstrated with different endcap units,then PSCs are fabricated using PBDB-T:WH1 and PBDB-T:WH7 as the active layers,and attain an average power conversion efficiency(PCE)of 2.58%and 6.24%,respectively.Further device physics studies afford the deep insight of structure variation influence on the device performance.This work provides a facile non-fullerene acceptor design strategy and shows how structure variations impact the PSC performance.展开更多
Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing ...Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing hole transport layer(HTL). In this work, eco-friendly glucose(Gl) as an interface modifier for HTL-free narrow bandgap tin-lead(Sn-Pb) PSCs is proposed. Gl not only enhances the wettability of the indium tin oxide to promote perovskite heterogeneous nucleation on substrate, but also realizes defect passivation by interacting with uncoordinated Pb^(2+) and Sn^(2+) in perovskite films. As a result, the quality of the perovskite films has been significantly improved, accompanied by reduced defects of bottom interface and optimized energy level structure of device, leading to an efficiency increase and a less nonradiative voltage loss of 0.102 V(for a bandgap of ~1.26 eV). Consequently, the optimized PSC delivers an unprecedented efficiency over 21% with high open-circuit voltage and enhanced stability, outperforming the control device. This work demonstrates a cost-effective approach to develop simplified structure high efficiency HTL-free Sn-Pb PSC.展开更多
There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processe...There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.展开更多
The exploration of efficient lead-free perovskite photoelectric active materials to develop high-performance photoelectrochemical(PEC)systems in aqueous solution is crucial to expand their PEC applications.Herein,we s...The exploration of efficient lead-free perovskite photoelectric active materials to develop high-performance photoelectrochemical(PEC)systems in aqueous solution is crucial to expand their PEC applications.Herein,we successfully constructed a high-performance PEC platform using ligand-free perovskite Cs2PdBr6 microcrystals(MCs)as the photoactive substance.The Cs2PdBr6 MCs showed narrow bandgap,wide absorption range,high electronic mobility and good stability in aqueous solutions.Particularly,the Cs2PdBr6 MCs exhibited an excellent photoresponse,the photocurrent density could reach as high as 98μA/cm^(2)under 10.18 mW/cm^(2)light irradiation in the absence of other electron acceptors.In addition of the extremely wide range of response wavelength,wide pH range and accelerated interfacial carrier transfer,the Cs2PdBr6 MCs demonstrated the significant potential of photocathode active material for applications in PEC sensors and optoelectronic devices.Therefore,this work indicates that Cs2PdBr6 MCs design is a highly efficient way to solve the intrinsic issues of perovskite material,predicting a promising strategy for high performance PEC application in aqueous ambience.展开更多
To achieve the rapid and real-time detection of triethylamine(TEA)gas,this study synthesized a gas sensor based on heterostructures of Fe_(2)O_(3)/MoO_(3) using a hydrothermal method.Fe_(2)O_(3)/MoO_(3) composites wit...To achieve the rapid and real-time detection of triethylamine(TEA)gas,this study synthesized a gas sensor based on heterostructures of Fe_(2)O_(3)/MoO_(3) using a hydrothermal method.Fe_(2)O_(3)/MoO_(3) composites with a narrow bandgap(1.1 eV)were successfully synthesized by constructing heterostructures.The rapid and efficient detection of triethylamine was achieved at 220℃.The response and response/recovery times of the Fe_(2)O_(3)/MoO_(3) sensor with 50×10^(−6) triethylamine were 132 s and 5 s/10 s,respectively.The Fe_(2)O_(3)/MoO_(3) sensor maintained a good response to triethylamine gas,even at 80%relative humidity.The sensing mechanism of the Fe_(2)O_(3)/MoO_(3) sensor can be described in terms of adsorption energy and electronic behavior of the sensing layer using density functional theory(DFT).The results are consistent with the excellent selectivity and rapid response/recovery of the Fe_(2)O_(3)/MoO_(3) gas sensor for triethylamine.Therefore,the construction of heterostructures to facilitate electron transmission is an effective strategy to achieve rapid detection of triethylamine and is worthy of further exploration and investigation.展开更多
The past decade has witnessed the rapid development of perovskite solar cells,with their power conversion efficiency increasing from an initial 3.8%to over 26%,approaching the Shockley-Queisser(S-Q)limit for single-ju...The past decade has witnessed the rapid development of perovskite solar cells,with their power conversion efficiency increasing from an initial 3.8%to over 26%,approaching the Shockley-Queisser(S-Q)limit for single-junction solar cells.Multijunction solar cells have garnered significant attention due to their tremendous potential to surpass the S-Q limit by reducing thermalization losses and wide light harvesting.The wide bandgap tunability of metal halide perovskite materials makes them highly suitable for sub-cells in tandem solar cells(TSCs).Currently,LONGi Green Energy Technology Co.,Ltd.in China has set a world record efficiency of 34.6% based on a dual-junction perovskitesilicon TSCs,far surpassing the single-junction efficiencies of each sub-cell.Consequently,perovskite based TSCs are widely regarded as the next-generation photovoltaic products in the solar industry.Despite the significant efficiency improvements,several challenges still impede the commercial application of perovskite based TSCs,such as the instability of perovskite materials and difficulties in achieving large-scale production.This review summarizes the progresses and optimization strategies of perovskite based TSCs.This review also identifies the critical issues hindering multijunction solar cells.Finally,the potential solutions to address these challenges are proposed to advance the development of perovskite based TSCs.展开更多
All-fused-ringπ-conjugated molecules have received considerable attention because of their unique electronic structures,low conformation disorder,and excellent optoelectronic properties.Most all-fused-ring molecules ...All-fused-ringπ-conjugated molecules have received considerable attention because of their unique electronic structures,low conformation disorder,and excellent optoelectronic properties.Most all-fused-ring molecules are p-type organic semiconductors and possess medium bandgaps.In this work,we design and synthesize an all-fused-ring molecule(FM1)with an n-type property and narrow bandgap,which is a 10-fused-ring system composed of one electrondeficient benzotriazole core,two electron-rich thienopyrrole bridging units,and two electron-deficient malononitrile-functionalized end-cappers.FM1 exhibits low-lying highest occupied molecular orbit/lowest unoccupied molecular orbit energy levels of−5.77 eV/−3.89 eV,high electron mobility of 6.0×10^(−4)cm^(2)V^(−1)s^(−1),an optical bandgap of 1.50 eV,and a maximum absorption wavelength of 769nm.Because of the all-fused-ring skeleton,FM1 shows superior photostability and chemical stability.We use FM1 as an electron acceptor and successfully construct organic solar cell(OSC)devices with a decent power conversion efficiency(PCE)of 10.8%.Most importantly,the intrinsic stability of FM1 leads to its excellent OSC device stability.After irradiation with simulated solar light for 16 h,while control of the OSC device of the state-of-the-art small molecule electron acceptor shows a 46%decrease of PCE,the FM1’s unencapsulated OSC device exhibits only a 9%decrease of PCE.展开更多
Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous stud...Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous studies on piezoelectric materials have primarily focused on ceramics or single-crystal materials characterized by wide band gaps(E_(g)>2.0 e V[2])and low electrical conductivity.In contrast,narrow-bandgap(E_(g)<0.5 eV[3])semiconductor materials typically exhibit high electrical conductivity,which is unfavorable for the effective accumulation of charges required to establish a stable voltage response.Consequently,experimental investigations into the piezoelectric effect of narrow-bandgap semiconductors are scarce.展开更多
Near-infrared(NIR)organic photodetectors(OPDs)are promising in flexible electronic and imaging sensor applications.However,high-performance NIR-II OPDs with photoresponse wavelength beyond 1000 nm are rare due to the ...Near-infrared(NIR)organic photodetectors(OPDs)are promising in flexible electronic and imaging sensor applications.However,high-performance NIR-II OPDs with photoresponse wavelength beyond 1000 nm are rare due to the lack of narrow bandgap molecular acceptors.In this work,an A-D-A′-D-Atype molecular acceptor with an onset absorption wavelength of 1150 nm was developed.Its narrow bandgap was benefited by the balanced resonance of the boron-nitrogen covalent bond(B–N)and boron-nitrogen coordination bond(B←N)in thienyl-fused 4-difluoro-4-bora-3a,4a-diaza-s-indacene(BODIPY)unit,as well as the strong intramolecular charge transfer(ICT)effect.The molecule showed a strong NIR absorption with an absorption peak at 1019 nm and an optical bandgap as low as 1.07 eV.Using the molecule as an electron acceptor in OPD device fabrication,a wide photoresponse wavelength range of 300 to∼1150 nm was achieved.At bias of−0.1 V,the device showed a low dark current density of 4.59×10^(−8) A cm^(−2) and high responsivity of 0.29 A W^(−1) at 970 nm,achieving a high peak specific detectivity of 2.39×1012 Jones and remaining a high specific detectivity of 1.59×10^(12) Jones at 1064 nm.These results demonstrate a feasible design of ultra-narrow bandgap molecular acceptors based on BODIPY unit induction of highly sensitive NIR-II OPDs.展开更多
Perovskite-organic tandem solar cells(TSCs)have emerged as a groundbreaking technology in the realm of photovoltaics,showcasing remarkable enhancements in efficiency and significant potential for practical application...Perovskite-organic tandem solar cells(TSCs)have emerged as a groundbreaking technology in the realm of photovoltaics,showcasing remarkable enhancements in efficiency and significant potential for practical applications.Perovskite-organic TSCs also exhibit facile fabrication surpassing that of all-perovskite or all-organic TSCs,attributing to the advantageous utilization of orthogonal solvents enabling sequential solution process for each subcell.The perovskite-organic TSCs capitalize on the complementary light absorption characteristics of perovskite and organic materials.There is a promising prospect of achieving further enhanced power conversion efficiencies by covering a broad range of the solar spectrum with optimized perovskite absorber,organic semiconductors as well as the interconnecting layer's optical and electrical properties.This review comprehensively analyzes the recent advancements in perovskite-organic TSCs,highlighting the synergistic effects of combining perovskite with a low open-circuit voltage deficit,organic materials with broader light absorption,and interconnecting layers with reduced optical and electrical loss.Meanwhile,the underlying device architecture design,regulation strategies,and key challenges facing the high performance of the perovskite-organic TSCs are also discussed.展开更多
Titanium dioxide(Ti O_2) is widely employed as a solid photocatalyst for solar energy conversion and environmental remediation. The ability to construct porous Ti O_2 with controlled particle size and narrowed bandgap...Titanium dioxide(Ti O_2) is widely employed as a solid photocatalyst for solar energy conversion and environmental remediation. The ability to construct porous Ti O_2 with controlled particle size and narrowed bandgap is an essential requirement for the design of highly efficient and recyclable photocatalysts. Here, we report a templatefree acetic acid induced method for the synthesis of visiblelight responsive carbon-doped Ti O_2 microplates with high crystallinity and mesoporous structure. It is shown that the electron-withdrawing bidentate carboxylate ligands derived from acetic acid can narrow the bandgap of Ti O_2(1.84 e V)substantially. Moreover, the resultant microplate photocatalysts exhibit excellent photocatalytic efficiency and solid–liquid separation performance, which will be beneficial for future industrial applications.展开更多
A large signal model for InP/InGaAs double heterojunction bipolar transistors including thermal effects has been reported,which demonstrated good agreements of simulations with measurements.On the basis of the previou...A large signal model for InP/InGaAs double heterojunction bipolar transistors including thermal effects has been reported,which demonstrated good agreements of simulations with measurements.On the basis of the previous model in which the double heterojunction effect,current blocking effect and high current effect in current expression are considered,the effect of bandgap narrowing with temperature has been considered in transport current while a formula for model parameters as a function of temperature has been developed.This model is implemented by Verilog-A and embedded in ADS.The proposed model is verified with DC and large signal measurements.展开更多
All-polymer solar cells(all-PSCs)have received attention due to their morphological stability under thermal and mechanical stresses.Currently,the highest reported power conversion efficiency of all-PSCs is over 17%,ac...All-polymer solar cells(all-PSCs)have received attention due to their morphological stability under thermal and mechanical stresses.Currently,the highest reported power conversion efficiency of all-PSCs is over 17%,achieved by utilizing polymerized small molecular acceptors(PSMAs).However,the need for higher regiospecificity to avoid forming isomers during polymerization of SMAs still challenges the further applications of all-PSCs.From this perspective,we focus on some recent studies and highlight the importance of controlling the regioregularity of PSMAs.In particular,integrating PSMAs with regioregularity endows the polymer acceptors with good absorption,superior backbone ordering,and optimal blend morphology compared with those obtained from regiorandom one.Moreover,the distinctive features that are derived from these regioregular PSMAs,such as the possibility of repeatable synthesis and reproducible device performance,herald a brighter future for scaling-up and commercializing all-PSCs.We expect this integrated strategy will inspire researchers to devote more efforts to further narrow the efficiency gap between the PSCs based on SMAs and PSMAs.Finally,we discuss the existing challenges and future prospects of PSMAs as new platform for further advancing all-PSCs.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51972312,51825204,21633009)。
文摘Nitrogen(N)doping has been widely adopted to improve the light absorption of TiO_(2).However,the newly introduced N-2p states are largely localized thus barely overlap with O-2p states in the valence band of TiO_(2),resulting in a shoulder-like absorption edge.To realize an apparent overlap between N-2p and O-2p states,charge compensation between N^(3-)and O^(2-)via electron transfer from oxygen vacancies(VO)to N dopants is one possible strategy.To verify this,in numerous doping configurations of N/VO-codoped anatase TiO_(2),we identified two types of VOposition independent N-dopant spatial orderings by efficient screening enabled with a newly designed structural descriptor.Compared with others,these two types of the N-dopant spatial orderings are highly beneficial for charge compensation to produce an apparent overlap between N-2p and O-2p states,therefore achieving a large bandgap narrowing.Furthermore,the two types of the N-dopant spatial orderings can also be generalized to N/VO-codoped rutile TiO_(2)for bandgap narrowing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472266,51202286,and 91422303)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB07020100)the ICDD
文摘A new layered Cu-based oxychalcogenide Ba_3Fe_2O_5Cu_2S_2 has been synthesized and its magnetic and electronic properties were revealed. Ba_3Fe_2O_5Cu_2S_2 is built up by alternatively stacking [Cu_2S_2]^（2-） layers and iron perovskite oxide[（FeO_2）（BaO）（FeO_2）]^（2-）layers along the c axis that are separated by barium ions with Fe^（3＋） fivefold coordinated by a square-pyramidal arrangement of oxygen. From the bond valence arguments, we inferred that in layered CuC h-based（Ch =S, Se, Te） compounds the ＋3 cation in perovskite oxide sheet prefers a square pyramidal site, while the lower valence cation prefers the square planar sites. The studies on susceptibility, transport, and optical reflectivity indicate that Ba_3Fe_2O_5Cu_2S_2 is an antiferromagnetic semiconductor with a Ne′el temperature of 121 K and an optical bandgap of 1.03 eV. The measurement of heat capacity from 10 K to room temperature shows no anomaly at 121 K. The Debye temperature is determined to be 113 K. Theoretical calculations indicate that the conduction band minimum is predominantly contributed by O 2p and 3 d states of Fe ions that antiferromagnetically arranged in FeO_2 layers. The Fe 3d states are located at lower energy and result in a narrow bandgap in comparison with that of the isostructural Sr_3Sc_2O_5Cu_2S_2.
基金financially supported by the National Key Research and Development Program of China(2022YFE0110300)the National Natural Science Foundation of China(52261145696 and 52473187)+1 种基金the“111”Projectthe Collaborative Innovation Center of Suzhou Nano Science and Technology,Soochow University。
文摘Organic-inorganic hybrid solar cells consisting of organic conjugated materials and inorganic quantum dots(QDs)have been of great interest during the past two decades.However,it is still challenging to select desired organic functional materials for fabricating hybrid films to maximize their photovoltaic performance.Herein,we report the synthesis of three narrow bandgap non-fullerene conjugated polymers and further demonstrate the importance and impact of polymer crystallinity in tuning the organic-inorganic hybrid interface towards improved photovoltaic performance.In specific,we develop an organic-inorganic hybrid active layer using a newly synthesized polymer with relatively weaker crystallinity and FAPbI_(3)QDs,enabling complementary absorption and favorable interface/morphology for efficient charge separation and transport.The champion PCDOT-T/FAPbI_(3)QD hybrid device achieves a record-high efficiency of 13.11%based on the one-step coating organic/QD hybrid bulk heterojunction blend,which is significantly improved relative to the semi-crystalline polymer PYIT-based hybrid device(11.23%)and pristine QD(10.51%).We believe these findings would provide new insight into the organic/QD interface to construct desired hybrid films for high-performing optoelectronic applications.
基金supported by the State Key Development Program for Basic Research of China (No. 2003CB314901)
文摘Heavy doping of the base in HBTs brings about a bandgap narrowing （BGN） effect, which modifies the intrinsic carrier density and disturbs the band offset, and thus leads to the change of the currents. Based on a thermionic-field-diffusion model that is used to the analyze the performance of an abrupt HBT with a heavydoped base, the conclusion is made that, although the BGN effect makes the currents obviously change due to the modification of the intrinsic carrier density, the band offsets disturbed by the BGN effect should also be taken into account in the analysis of the electrical characteristics of abrupt HBTs. In addition, the BGN effect changes the bias voltage for the onset of Kirk effects.
基金The authors would like to acknowledge financial support from the Australian Research Council through its DP and FF programs. Mu Xiao acknowledges support from the Australian Government Research Training Program Scholarship. Financial support from the National Natural Science Foundation of China （513228201） is also highly appreciated.
文摘Photocatalytic water splitting, which directly converts solar energy into hydrogen, is one of the most desirable solar-energy-conversion approaches. The ultimate target of photocatalysis is to explore efficient and stable photocatalysts for solar water splitting. Tantalum （oxy）nitride-based materials are a class of the most promising photocatalysts for solar water splitting because of their narrow bandgaps and sufficient band energy potentials for water splitting. Tantalum （oxy）nitride-based photocatalysts have experienced intensive exploration, and encouraging progress has been achieved over the past years. However, the solar- to-hydrogen （STH） conversion efficiency is still very far from its theoretical value. The question of how to better design these materials in order to further improve their water-splitting capability is of interest and importance. This review summarizes the development of tantalum （oxy）nitride-based photocatalysts for solar water spitting. Special interest is paid to important strategies for improving photocatalytic water- splitting efficiency. This paper also proposes future trends to explore in the research area of tantalum-based narrow bandgap photocatalysts for solar water splitting.
基金support from the Research Council of Norway provided by the Norwegian Center for Transmission Electron Microscopy,NORTEM(197405/F50)NTNU NanoLab(grant number 245963)which have provided the characterization toolsthe strategic funding support provided by Department of Chemical Engineering,NTNU,Trondheim,Norway.
文摘To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H_(2) generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H_(2) under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H_(2) generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(N_(D))in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.
基金financially supported by the National Natural Science Foundation of China (Nos.51811530096, 21875286)the National Key Research & Development Projects of China (No.2017YFA0206600)Science Fund for Distinguished Young Scholars of Hunan Province (No.2017JJ1029)
文摘Improving the performance and reducing the manufacturing costs are the main directions for the development of organic solar cells in the future.Here,the strategy that uses chemical structure modification to optimize the photoelectric properties is reported.A new narrow bandgap(1.30 eV)chlorinated non-fullerene electron acceptor(Y15),based on benzo[d][1,2,3] triazole with two 3-undecylthieno[2’,3’:4,5] thieno[3,2-b] pyrrole fused-7-heterocyclic ring,with absorption edge extending to the near-infrared(NIR) region,namely A-DA’D-A type structure,is designed and synthesized.Its electrochemical and optoelectronic properties are systematically investigated.Benefitting from its NIR light harvesting,the fabricated photovoltaic devices based on Y15 deliver a high power conversion efficiency(PCE) of 14.13%,when blending with a wide bandgap polymer donor PM6.Our results show that the A-DA’D-A type molecular design and application of near-infrared electron acceptors have the potential to further improve the PCE of polymer solar cells(PSCs).
基金National Natural Science Foundation of China(No.21805032)Natural Science Foundation of Shanghai,China(No.19ZR1401400)Fundamental Research Funds for the Central Universities,China(No.20D128502).
文摘Two acceptor-donor-acceptor(A-D-A)type non-fullerene acceptors(namely WH1 and WH7)containing the oxindole-based bridge are designed and synthesized for polymer solar cells(PSCs)applications.The bridge unit is introduced through a precursor(6-bromo-1-octylindoline-2,3-dione)that contains both bromine and carbonyl and provides the feasibility of the Pd-catalyzed cross-coupling reaction and the Knoevenagel condensation,respectively.This facile synthetic approach exhibits the potential to gain high performance non-fullerene acceptors through extendingπ-conjugated backbone with strong light-absorbing building blocks.The synthesis and properties of WH1 and WH7 are demonstrated with different endcap units,then PSCs are fabricated using PBDB-T:WH1 and PBDB-T:WH7 as the active layers,and attain an average power conversion efficiency(PCE)of 2.58%and 6.24%,respectively.Further device physics studies afford the deep insight of structure variation influence on the device performance.This work provides a facile non-fullerene acceptor design strategy and shows how structure variations impact the PSC performance.
基金supported by the National Natural Science Foundation of China (Grant No. 12074321)the Young Science and Technology Talents Development Project of Guizhou Provincial Education Department (Grant No. QJH-KY [2022]012)+2 种基金the Fundamental Research Funds for the Central Universities (Grant No. SWU020019)the Natural Science Foundation of Chongqing (Grant No. cstc2020jcyjmsxmx0648)the Chongqing Graduate Student Research Innovation Project (Grant No. CYB22119)。
文摘Achieving highly-efficient and stable perovskite solar cells(PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing hole transport layer(HTL). In this work, eco-friendly glucose(Gl) as an interface modifier for HTL-free narrow bandgap tin-lead(Sn-Pb) PSCs is proposed. Gl not only enhances the wettability of the indium tin oxide to promote perovskite heterogeneous nucleation on substrate, but also realizes defect passivation by interacting with uncoordinated Pb^(2+) and Sn^(2+) in perovskite films. As a result, the quality of the perovskite films has been significantly improved, accompanied by reduced defects of bottom interface and optimized energy level structure of device, leading to an efficiency increase and a less nonradiative voltage loss of 0.102 V(for a bandgap of ~1.26 eV). Consequently, the optimized PSC delivers an unprecedented efficiency over 21% with high open-circuit voltage and enhanced stability, outperforming the control device. This work demonstrates a cost-effective approach to develop simplified structure high efficiency HTL-free Sn-Pb PSC.
基金financially supported by the Joint Funds Project funding from Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B1515120083)the National Natural Science Foundation of China(Grant No.U19A2089)+4 种基金the Key Fundamental Research Project funding from the Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20200109141014474)the National Key Research and Development Project from the Ministry of Science and Technology of China(Grants Nos.2016YFA0202400 and 2016YFA0202404)the Peacock Team Project from Shenzhen Science and Technology Innovation Committee(Grant No.KQTD2015033110182370)Shenzhen Engineering R&D Center for Flexible Solar Cells project funding from Shenzhen Development and Reform Committee(Grant No.2019-126)the Guangdong-Hong Kong-Macao Joint Laboratory(Grant No.2019B121205001).
文摘There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.
基金funded by the National Natural Science Foundation of China(22374021)the Joint Funds for the Innovation of Science and Technology of Fujian Province(2021Y9010)+2 种基金Zong Lian Plan Talent Support Project of the Fujian Medical University(XN240006)Program for Fujian Youth Talent Support Project(2019B016)Program for Fujian Top-notch Innovative Personnel(Fujian Commission Talent[2018]No.5).
文摘The exploration of efficient lead-free perovskite photoelectric active materials to develop high-performance photoelectrochemical(PEC)systems in aqueous solution is crucial to expand their PEC applications.Herein,we successfully constructed a high-performance PEC platform using ligand-free perovskite Cs2PdBr6 microcrystals(MCs)as the photoactive substance.The Cs2PdBr6 MCs showed narrow bandgap,wide absorption range,high electronic mobility and good stability in aqueous solutions.Particularly,the Cs2PdBr6 MCs exhibited an excellent photoresponse,the photocurrent density could reach as high as 98μA/cm^(2)under 10.18 mW/cm^(2)light irradiation in the absence of other electron acceptors.In addition of the extremely wide range of response wavelength,wide pH range and accelerated interfacial carrier transfer,the Cs2PdBr6 MCs demonstrated the significant potential of photocathode active material for applications in PEC sensors and optoelectronic devices.Therefore,this work indicates that Cs2PdBr6 MCs design is a highly efficient way to solve the intrinsic issues of perovskite material,predicting a promising strategy for high performance PEC application in aqueous ambience.
基金supported by National Natural Science Foundation of China(Nos.61102006 and 51803109)Natural Science Foundation of Shandong Province,China(ZR2022MF234 and No.ZR2018LE006).
文摘To achieve the rapid and real-time detection of triethylamine(TEA)gas,this study synthesized a gas sensor based on heterostructures of Fe_(2)O_(3)/MoO_(3) using a hydrothermal method.Fe_(2)O_(3)/MoO_(3) composites with a narrow bandgap(1.1 eV)were successfully synthesized by constructing heterostructures.The rapid and efficient detection of triethylamine was achieved at 220℃.The response and response/recovery times of the Fe_(2)O_(3)/MoO_(3) sensor with 50×10^(−6) triethylamine were 132 s and 5 s/10 s,respectively.The Fe_(2)O_(3)/MoO_(3) sensor maintained a good response to triethylamine gas,even at 80%relative humidity.The sensing mechanism of the Fe_(2)O_(3)/MoO_(3) sensor can be described in terms of adsorption energy and electronic behavior of the sensing layer using density functional theory(DFT).The results are consistent with the excellent selectivity and rapid response/recovery of the Fe_(2)O_(3)/MoO_(3) gas sensor for triethylamine.Therefore,the construction of heterostructures to facilitate electron transmission is an effective strategy to achieve rapid detection of triethylamine and is worthy of further exploration and investigation.
基金supported by the National Natural Science Foundation of China(62274018)the Xinjiang Construction Corps Key Areas of Science and Technology Research Project(2023AB029)the Key Project of Chongqing Overseas Students Returning to China Entrepreneurship and Innovation Support Plan(cx2023006).
文摘The past decade has witnessed the rapid development of perovskite solar cells,with their power conversion efficiency increasing from an initial 3.8%to over 26%,approaching the Shockley-Queisser(S-Q)limit for single-junction solar cells.Multijunction solar cells have garnered significant attention due to their tremendous potential to surpass the S-Q limit by reducing thermalization losses and wide light harvesting.The wide bandgap tunability of metal halide perovskite materials makes them highly suitable for sub-cells in tandem solar cells(TSCs).Currently,LONGi Green Energy Technology Co.,Ltd.in China has set a world record efficiency of 34.6% based on a dual-junction perovskitesilicon TSCs,far surpassing the single-junction efficiencies of each sub-cell.Consequently,perovskite based TSCs are widely regarded as the next-generation photovoltaic products in the solar industry.Despite the significant efficiency improvements,several challenges still impede the commercial application of perovskite based TSCs,such as the instability of perovskite materials and difficulties in achieving large-scale production.This review summarizes the progresses and optimization strategies of perovskite based TSCs.This review also identifies the critical issues hindering multijunction solar cells.Finally,the potential solutions to address these challenges are proposed to advance the development of perovskite based TSCs.
基金support by the National Key Research and Development Program of China(grant no.2019YFA0705900)funded by MOST and the National Natural Science Foundation of China(grant nos.22135007 and 21875244).
文摘All-fused-ringπ-conjugated molecules have received considerable attention because of their unique electronic structures,low conformation disorder,and excellent optoelectronic properties.Most all-fused-ring molecules are p-type organic semiconductors and possess medium bandgaps.In this work,we design and synthesize an all-fused-ring molecule(FM1)with an n-type property and narrow bandgap,which is a 10-fused-ring system composed of one electrondeficient benzotriazole core,two electron-rich thienopyrrole bridging units,and two electron-deficient malononitrile-functionalized end-cappers.FM1 exhibits low-lying highest occupied molecular orbit/lowest unoccupied molecular orbit energy levels of−5.77 eV/−3.89 eV,high electron mobility of 6.0×10^(−4)cm^(2)V^(−1)s^(−1),an optical bandgap of 1.50 eV,and a maximum absorption wavelength of 769nm.Because of the all-fused-ring skeleton,FM1 shows superior photostability and chemical stability.We use FM1 as an electron acceptor and successfully construct organic solar cell(OSC)devices with a decent power conversion efficiency(PCE)of 10.8%.Most importantly,the intrinsic stability of FM1 leads to its excellent OSC device stability.After irradiation with simulated solar light for 16 h,while control of the OSC device of the state-of-the-art small molecule electron acceptor shows a 46%decrease of PCE,the FM1’s unencapsulated OSC device exhibits only a 9%decrease of PCE.
文摘Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous studies on piezoelectric materials have primarily focused on ceramics or single-crystal materials characterized by wide band gaps(E_(g)>2.0 e V[2])and low electrical conductivity.In contrast,narrow-bandgap(E_(g)<0.5 eV[3])semiconductor materials typically exhibit high electrical conductivity,which is unfavorable for the effective accumulation of charges required to establish a stable voltage response.Consequently,experimental investigations into the piezoelectric effect of narrow-bandgap semiconductors are scarce.
基金the financial support from the National Natural Science Foundation of China(grant no.22135007)the Natural Science Foundation of Jilin Province,China(grant no.20230101122JC).
文摘Near-infrared(NIR)organic photodetectors(OPDs)are promising in flexible electronic and imaging sensor applications.However,high-performance NIR-II OPDs with photoresponse wavelength beyond 1000 nm are rare due to the lack of narrow bandgap molecular acceptors.In this work,an A-D-A′-D-Atype molecular acceptor with an onset absorption wavelength of 1150 nm was developed.Its narrow bandgap was benefited by the balanced resonance of the boron-nitrogen covalent bond(B–N)and boron-nitrogen coordination bond(B←N)in thienyl-fused 4-difluoro-4-bora-3a,4a-diaza-s-indacene(BODIPY)unit,as well as the strong intramolecular charge transfer(ICT)effect.The molecule showed a strong NIR absorption with an absorption peak at 1019 nm and an optical bandgap as low as 1.07 eV.Using the molecule as an electron acceptor in OPD device fabrication,a wide photoresponse wavelength range of 300 to∼1150 nm was achieved.At bias of−0.1 V,the device showed a low dark current density of 4.59×10^(−8) A cm^(−2) and high responsivity of 0.29 A W^(−1) at 970 nm,achieving a high peak specific detectivity of 2.39×1012 Jones and remaining a high specific detectivity of 1.59×10^(12) Jones at 1064 nm.These results demonstrate a feasible design of ultra-narrow bandgap molecular acceptors based on BODIPY unit induction of highly sensitive NIR-II OPDs.
基金Guangdong Grants,Grant/Award Numbers:2021QN02L138,2021ZT09C064Shenzhen Science and Technology Program,Grant/Award Numbers:JCYJ20220530115013029,ZDSYS20220527171403009+1 种基金National Natural Science Foundation of China,Grant/Award Number:22109067Guangdong Provincial Science and Technology Program,Grant/Award Number:2022A1515010085。
文摘Perovskite-organic tandem solar cells(TSCs)have emerged as a groundbreaking technology in the realm of photovoltaics,showcasing remarkable enhancements in efficiency and significant potential for practical applications.Perovskite-organic TSCs also exhibit facile fabrication surpassing that of all-perovskite or all-organic TSCs,attributing to the advantageous utilization of orthogonal solvents enabling sequential solution process for each subcell.The perovskite-organic TSCs capitalize on the complementary light absorption characteristics of perovskite and organic materials.There is a promising prospect of achieving further enhanced power conversion efficiencies by covering a broad range of the solar spectrum with optimized perovskite absorber,organic semiconductors as well as the interconnecting layer's optical and electrical properties.This review comprehensively analyzes the recent advancements in perovskite-organic TSCs,highlighting the synergistic effects of combining perovskite with a low open-circuit voltage deficit,organic materials with broader light absorption,and interconnecting layers with reduced optical and electrical loss.Meanwhile,the underlying device architecture design,regulation strategies,and key challenges facing the high performance of the perovskite-organic TSCs are also discussed.
基金supported by the National Natural Science Foundation of China(20966006)the Natural Science Foundation of the Inner Mongolia Autonomous Region(2014MS0218)the Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region(NMGIRT-A1603)
文摘Titanium dioxide(Ti O_2) is widely employed as a solid photocatalyst for solar energy conversion and environmental remediation. The ability to construct porous Ti O_2 with controlled particle size and narrowed bandgap is an essential requirement for the design of highly efficient and recyclable photocatalysts. Here, we report a templatefree acetic acid induced method for the synthesis of visiblelight responsive carbon-doped Ti O_2 microplates with high crystallinity and mesoporous structure. It is shown that the electron-withdrawing bidentate carboxylate ligands derived from acetic acid can narrow the bandgap of Ti O_2(1.84 e V)substantially. Moreover, the resultant microplate photocatalysts exhibit excellent photocatalytic efficiency and solid–liquid separation performance, which will be beneficial for future industrial applications.
基金supported by the State Key Development Program tor Basic Research of China(No.2010CB327504)
文摘A large signal model for InP/InGaAs double heterojunction bipolar transistors including thermal effects has been reported,which demonstrated good agreements of simulations with measurements.On the basis of the previous model in which the double heterojunction effect,current blocking effect and high current effect in current expression are considered,the effect of bandgap narrowing with temperature has been considered in transport current while a formula for model parameters as a function of temperature has been developed.This model is implemented by Verilog-A and embedded in ADS.The proposed model is verified with DC and large signal measurements.
基金Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20211598National Key Research and Development Program of China,Grant/Award Number:2017YFA0206600+2 种基金Outstanding Youth Science and Technology Foundation of Xi'an University of Science and Technology,Grant/Award Number:2019YQ3-03Science and Technology Program of Shaanxi Province,Grant/Award Number:2019JQ-244National Natural Science Foundation of China,Grant/Award Numbers:21961160720,51922032,21772030,51773045,51803144,52073198,21905225。
文摘All-polymer solar cells(all-PSCs)have received attention due to their morphological stability under thermal and mechanical stresses.Currently,the highest reported power conversion efficiency of all-PSCs is over 17%,achieved by utilizing polymerized small molecular acceptors(PSMAs).However,the need for higher regiospecificity to avoid forming isomers during polymerization of SMAs still challenges the further applications of all-PSCs.From this perspective,we focus on some recent studies and highlight the importance of controlling the regioregularity of PSMAs.In particular,integrating PSMAs with regioregularity endows the polymer acceptors with good absorption,superior backbone ordering,and optimal blend morphology compared with those obtained from regiorandom one.Moreover,the distinctive features that are derived from these regioregular PSMAs,such as the possibility of repeatable synthesis and reproducible device performance,herald a brighter future for scaling-up and commercializing all-PSCs.We expect this integrated strategy will inspire researchers to devote more efforts to further narrow the efficiency gap between the PSCs based on SMAs and PSMAs.Finally,we discuss the existing challenges and future prospects of PSMAs as new platform for further advancing all-PSCs.
