Recently, graphene-based photodetectors have been rapidly developed. However, their photoresponsivities are generally low due to the weak optical absorption strength of graphene. In this paper, we fabricate photocondu...Recently, graphene-based photodetectors have been rapidly developed. However, their photoresponsivities are generally low due to the weak optical absorption strength of graphene. In this paper, we fabricate photoconductive multi-layer graphene（MLG） photodetectors on etched silicon-on-insulator substrates. A photoresponsivity exceeding 200 A·W-1is obtained, which enables most optoelectronic application. In addition, according to the analyses of the high photoresponsivity and long photoresponse time, we conclude that the working mechanism of the device is photoconductive effect. The process of photons conversion into conducting electrons is also described in detail. Finally, according to the distinct difference between the photoresponses at 1550 nm and 808 nm, we estimate that the position of the trapping energy is somewhere between 0.4 e V and 0.76 e V, higher than the Fermi energy of MLG. Our work paves a new way for fabricating the graphene photoconductive photodetectors.展开更多
Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applicatio...Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applications in the field of high-performance wide-spectrum detection.In this study,a self-powered broadband photodetector based on a Si/TiO_(2)heterojunction is proposed.The detector has a pyramidal structure.By constructing a pyramidal microstructure on the surface of silicon,the light capture and absorption efficiency is significantly improved,representing a breakthrough in response performance in the visible and near-infrared(NIR)bands.In order to further enhance the photoelectric response in the UV band,a TiO_(2)layer was coated on the surface of the silicon pyramid through a simple spin-coating method and annealing process.The introduction of TiO_(2)effectively broadened the spectral response range of the photoelectric detector and further improved the light absorption of the device.Meanwhile,due to the built-in electric field formed by the n-TiO_(2)/p-Si heterojunction,the dark current was effectively reduced,and the responsivity was improved.Experiments showed that the device exhibits high responsivity,high detectivity,and relatively low dark current in the range of 365-1305 nm.Under light at 780 nm,the device’s on-off ratio reached 2.7×10^(3);its specific detectivity,D^(*),was 3.9×10^(11)Jones;and its responsivity reached 0.174 A/W.In addition,this detector does not require the assistance of expensive equipment.Its preparation process is simple and inexpensive,and there is no need for an external power supply,which gives it broad application potential in wearable devices,environmental monitoring,communications,biosensing,and other fields.This study provides a brand-new strategy for the design of new wide-spectrum detectors.展开更多
Two-dimensionalα-In_(2)Se_(3)exhibits simultaneous intercorrelated in-plane and out-of-plane polarization,making it a highly promising material for use in memories,synapses,sensors,detectors,and optoelectronic device...Two-dimensionalα-In_(2)Se_(3)exhibits simultaneous intercorrelated in-plane and out-of-plane polarization,making it a highly promising material for use in memories,synapses,sensors,detectors,and optoelectronic devices.With its narrow bandgap,α-In_(2)Se_(3)is particularly attractive for applications in photodetection.However,relatively little research has been conducted on the out-of-plane photoconductive and bulk photovoltaic effects inα-In_(2)Se_(3).This limits the potential ofα-In_(2)Se_(3)in the device innovation and performance modification.Herein,we have developed anα-In_(2)Se_(3)-based heterojunction with a transparent electrode of two-dimensional Ta_(2)NiS_(5).The out-of-plane electric field can effectively separate the photo-generated electron-hole pairs in the heterojunction,resulting in an out-of-plane responsivity(R),external quantum efficiency(EQE),and specific detectivity(D*)of 0.78 mA/W,10−3%and 1.14×10^(8)Jones,respectively.The out-of-plane bulk photovoltaic effect has been demonstrated by changes in the short circuit current(SCC)and open circuit voltage(V_(oc))with different optical power intensity and temperature,which indicates thatα-In_(2)Se_(3)-based heterojunctions has application potential in mid-far infrared light detection based on its out-of-plane photoconductive and bulk photovoltaic effects.Although the out-of-plane photoconductive and bulk photovoltaic effects are relatively lower than that of traditional materials,the findings pave the way for a better understanding of the out-of-plane characteristics of two-dimensionalα-In_(2)Se_(3)and related heterojunctions.Furthermore,the results highlight the application potential ofα-In_(2)Se_(3)in low-power device innovation and performance modification.展开更多
Infrared(IR)photodetectors(PDs)are crucial for medical imaging,optical communication,security surveillance,remote sensing,and gas identification.In this Letter,we systematically investigated a room temperature IR PD b...Infrared(IR)photodetectors(PDs)are crucial for medical imaging,optical communication,security surveillance,remote sensing,and gas identification.In this Letter,we systematically investigated a room temperature IR PD based on twodimensional b-As_(0.5)P_(0.5),a relatively unexplored component of b-As P alloys.We synthesized high-quality b-As_(0.5)P_(0.5) flakes via the chemical vapor transport(CVT)method with precisely controlled conditions.The fabricated b-As_(0.5)P_(0.5) PD exhibits excellent photoconductivity,high responsivity,and a fast response in the visible and near-infrared(Vis-NIR)band.It achieves a responsivity of~0.209 A·W^(-1) and a response time of~16.6μs under 1550 nm IR illumination.High-resolution single-pixel point optical imaging and high-speed optical communication were realized by the b-As_(0.5)P_(0.5) PDs.This study confirms that b-As_(0.5)P_(0.5) materials are highly promising for advanced IR optoelectronic applications.展开更多
Inorganic-organic metal halide perovskite light harvester-based perovskite solar cells(PSCs)with widely tunable bandgap have achieved rapid growth in power conversion efficiency,which exceeds 25%now.It is deliberated ...Inorganic-organic metal halide perovskite light harvester-based perovskite solar cells(PSCs)with widely tunable bandgap have achieved rapid growth in power conversion efficiency,which exceeds 25%now.It is deliberated that if a semitransparent solar cell made of wider bandgap materials was placed on top of a narrow bandgap materials-based solar cell such as a silicon solar cell,with proper optical and electrical arrangements,the resultant tandem device consisting of two subcells could more effectively utilize the solar spectrum than a single junction solar cell.In a perovskite/silicon tandem solar cell(PSTSC),a semitransparent PSC with a wider bandgap is placed on top of a narrow bandgap silicon solar cell.The PSC efficiently harvests the higher energy photons in the ultraviolet and visible regions of the solar spectrum while the silicon solar cell can convert the photons of the infrared region to power.The PSTSC is proposed as a potential candidate to overcome the Shockley-Queisser limit of single-junction silicon solar cells.Though the theoretical limit of a PSTSC is calculated as~42%,its actual efficiency achieved until now is less than 30%.Therefore,a great scope of research exists in improving the efficiency of PSTSCs.Current issues of stability and upscaling of the device in PSCs are also a matter of concern for PSTSCs.A tandem device consists of multiple parts,and different configurations can be applied,thus tuning the architecture of the device.Altering various parts may result in significant changes in the efficiency of the device.In this review,competing architectures of otherwise comparable devices are compared in terms of photovoltaic properties.Thus,future directions to improve the efficiency of the device based on architecture design are proposed herein.In particular,the influence of the polarity of PSCs and the surface morphology of silicon solar cells(both front and rear)on determining the properties of the PSTSC are discussed.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402404)the High-Tech Research and Development Program of China(Grant Nos.2013AA031401,2015AA016902,and 2015AA016904)the National Natural Science Foundation of China(Grant Nos.61674136,61176053,61274069,and 61435002)
文摘Recently, graphene-based photodetectors have been rapidly developed. However, their photoresponsivities are generally low due to the weak optical absorption strength of graphene. In this paper, we fabricate photoconductive multi-layer graphene（MLG） photodetectors on etched silicon-on-insulator substrates. A photoresponsivity exceeding 200 A·W-1is obtained, which enables most optoelectronic application. In addition, according to the analyses of the high photoresponsivity and long photoresponse time, we conclude that the working mechanism of the device is photoconductive effect. The process of photons conversion into conducting electrons is also described in detail. Finally, according to the distinct difference between the photoresponses at 1550 nm and 808 nm, we estimate that the position of the trapping energy is somewhere between 0.4 e V and 0.76 e V, higher than the Fermi energy of MLG. Our work paves a new way for fabricating the graphene photoconductive photodetectors.
基金supported by the National Natural Science Foundation of China(Grant Nos.51902255 and 51803168)the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-YB-015)+1 种基金the Shaanxi Province Key Research and Development Projects(Grant No.2022GY-356)the Shaanxi Universities’Youth Innovation Team(Grant No.23JP174).
文摘Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applications in the field of high-performance wide-spectrum detection.In this study,a self-powered broadband photodetector based on a Si/TiO_(2)heterojunction is proposed.The detector has a pyramidal structure.By constructing a pyramidal microstructure on the surface of silicon,the light capture and absorption efficiency is significantly improved,representing a breakthrough in response performance in the visible and near-infrared(NIR)bands.In order to further enhance the photoelectric response in the UV band,a TiO_(2)layer was coated on the surface of the silicon pyramid through a simple spin-coating method and annealing process.The introduction of TiO_(2)effectively broadened the spectral response range of the photoelectric detector and further improved the light absorption of the device.Meanwhile,due to the built-in electric field formed by the n-TiO_(2)/p-Si heterojunction,the dark current was effectively reduced,and the responsivity was improved.Experiments showed that the device exhibits high responsivity,high detectivity,and relatively low dark current in the range of 365-1305 nm.Under light at 780 nm,the device’s on-off ratio reached 2.7×10^(3);its specific detectivity,D^(*),was 3.9×10^(11)Jones;and its responsivity reached 0.174 A/W.In addition,this detector does not require the assistance of expensive equipment.Its preparation process is simple and inexpensive,and there is no need for an external power supply,which gives it broad application potential in wearable devices,environmental monitoring,communications,biosensing,and other fields.This study provides a brand-new strategy for the design of new wide-spectrum detectors.
基金supported by the National Natural Science Foundation of China(No.12175191)Natural Science Foundation of Hunan Province,China(Nos.2022JJ30566)the Research Foundation of Education Bureau of Hunan Province,China(Grant No.22A0134).
文摘Two-dimensionalα-In_(2)Se_(3)exhibits simultaneous intercorrelated in-plane and out-of-plane polarization,making it a highly promising material for use in memories,synapses,sensors,detectors,and optoelectronic devices.With its narrow bandgap,α-In_(2)Se_(3)is particularly attractive for applications in photodetection.However,relatively little research has been conducted on the out-of-plane photoconductive and bulk photovoltaic effects inα-In_(2)Se_(3).This limits the potential ofα-In_(2)Se_(3)in the device innovation and performance modification.Herein,we have developed anα-In_(2)Se_(3)-based heterojunction with a transparent electrode of two-dimensional Ta_(2)NiS_(5).The out-of-plane electric field can effectively separate the photo-generated electron-hole pairs in the heterojunction,resulting in an out-of-plane responsivity(R),external quantum efficiency(EQE),and specific detectivity(D*)of 0.78 mA/W,10−3%and 1.14×10^(8)Jones,respectively.The out-of-plane bulk photovoltaic effect has been demonstrated by changes in the short circuit current(SCC)and open circuit voltage(V_(oc))with different optical power intensity and temperature,which indicates thatα-In_(2)Se_(3)-based heterojunctions has application potential in mid-far infrared light detection based on its out-of-plane photoconductive and bulk photovoltaic effects.Although the out-of-plane photoconductive and bulk photovoltaic effects are relatively lower than that of traditional materials,the findings pave the way for a better understanding of the out-of-plane characteristics of two-dimensionalα-In_(2)Se_(3)and related heterojunctions.Furthermore,the results highlight the application potential ofα-In_(2)Se_(3)in low-power device innovation and performance modification.
基金supported by the National Natural Science Foundation of China(No.62105018)。
文摘Infrared(IR)photodetectors(PDs)are crucial for medical imaging,optical communication,security surveillance,remote sensing,and gas identification.In this Letter,we systematically investigated a room temperature IR PD based on twodimensional b-As_(0.5)P_(0.5),a relatively unexplored component of b-As P alloys.We synthesized high-quality b-As_(0.5)P_(0.5) flakes via the chemical vapor transport(CVT)method with precisely controlled conditions.The fabricated b-As_(0.5)P_(0.5) PD exhibits excellent photoconductivity,high responsivity,and a fast response in the visible and near-infrared(Vis-NIR)band.It achieves a responsivity of~0.209 A·W^(-1) and a response time of~16.6μs under 1550 nm IR illumination.High-resolution single-pixel point optical imaging and high-speed optical communication were realized by the b-As_(0.5)P_(0.5) PDs.This study confirms that b-As_(0.5)P_(0.5) materials are highly promising for advanced IR optoelectronic applications.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB1500103)the Joint Funds of the National Natural Science Foundation of China(Grant No.U21A2072)+7 种基金the Natural Science Foundation of Tianjin(Grant No.20JCQNJC02070)China Postdoctoral Science Foundation(Grant No.2020T130317)the Overseas Expertise Introduction Project for Discipline Innovation of Higher Education of China(Grant No.B16027)Tianjin Science and Technology Project(Grant No.18ZXJMTG00220)the Key R&D Program of Hebei Province(Grant No.19214301D)the Haihe Laboratory of Sustainable Chemical Transformationsthe Fundamental Research Funds for the Central UniversitiesNankai University。
文摘Inorganic-organic metal halide perovskite light harvester-based perovskite solar cells(PSCs)with widely tunable bandgap have achieved rapid growth in power conversion efficiency,which exceeds 25%now.It is deliberated that if a semitransparent solar cell made of wider bandgap materials was placed on top of a narrow bandgap materials-based solar cell such as a silicon solar cell,with proper optical and electrical arrangements,the resultant tandem device consisting of two subcells could more effectively utilize the solar spectrum than a single junction solar cell.In a perovskite/silicon tandem solar cell(PSTSC),a semitransparent PSC with a wider bandgap is placed on top of a narrow bandgap silicon solar cell.The PSC efficiently harvests the higher energy photons in the ultraviolet and visible regions of the solar spectrum while the silicon solar cell can convert the photons of the infrared region to power.The PSTSC is proposed as a potential candidate to overcome the Shockley-Queisser limit of single-junction silicon solar cells.Though the theoretical limit of a PSTSC is calculated as~42%,its actual efficiency achieved until now is less than 30%.Therefore,a great scope of research exists in improving the efficiency of PSTSCs.Current issues of stability and upscaling of the device in PSCs are also a matter of concern for PSTSCs.A tandem device consists of multiple parts,and different configurations can be applied,thus tuning the architecture of the device.Altering various parts may result in significant changes in the efficiency of the device.In this review,competing architectures of otherwise comparable devices are compared in terms of photovoltaic properties.Thus,future directions to improve the efficiency of the device based on architecture design are proposed herein.In particular,the influence of the polarity of PSCs and the surface morphology of silicon solar cells(both front and rear)on determining the properties of the PSTSC are discussed.
