A new crosslinked polymer,called P65,with appropriate photo-electrochemical,opto-electronic,and thermal properties,has been designed and synthesized as an efficient,dopant-free,hole-transport material(HTM)for n-i-p ty...A new crosslinked polymer,called P65,with appropriate photo-electrochemical,opto-electronic,and thermal properties,has been designed and synthesized as an efficient,dopant-free,hole-transport material(HTM)for n-i-p type planar perovskite solar cells(PSCs).P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,90-xanthene]-30,60-diol(SFX-OH)-based monomer X65 through a freeradical polymerization reaction.The combination of a three-dimensional(3 D)SFX core unit,holetransport methoxydiphenylamine group,and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties.By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs,a power conversion efficiency(PCE)of up to 17.7%is achieved.To the best of our knowledge,this is the first time a 3 D,crosslinked,polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs.This study provides a new strategy for the future development of a 3 D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial,large-scale applications in future PSCs.展开更多
Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material （HTM） POZ6-2 using phenoxazine （POZ） as central unit and dicyanovinyl units as elec...Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material （HTM） POZ6-2 using phenoxazine （POZ） as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction ofa 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-flee HTM in perovskite solar cells （PSCs） and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine （TBP） and lithium bis（trifluoromethanesulfonyl） imide （LiTFS1）. Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.展开更多
Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands...Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.展开更多
CONSPECTUS:Organic hole-transporting materials(HTMs)are of importance in the progress of new-generation photovoltaics,notably in perovskite solar cells(PSCs),solid-state dye-sensitized solar cells(sDSCs),and organic s...CONSPECTUS:Organic hole-transporting materials(HTMs)are of importance in the progress of new-generation photovoltaics,notably in perovskite solar cells(PSCs),solid-state dye-sensitized solar cells(sDSCs),and organic solar cells(OSCs).These materials play a vital role in hole collection and transportation,significantly impacting the power conversion efficiency(PCE)and overall stability of photovoltaic devices.The emergence of spiro(fluorene-9,9′-xanthene)(SFX)as a novel building block for organic HTMs has gained considerable attention in the field of photovoltaics.Its facile one-pot synthetic approach,straightforward purification,and physiochemical properties over the prototype HTM spiro-OMeTAD have positioned SFX as a highly attractive alternative.In this Account,we present a comprehensive and in-depth summary of our research work,focusing on the advancements in SFX-based organic HTMs in photovoltaic devices with a particular emphasis on PSCs and sDSCs.Several key objectives of our research have been focused on exploring strategies to improve the properties of SFX-based HTMs.(i)One of the critical aspects we have addressed is the improvement of film quality.By carefully designing the molecular structure and employing suitable synthetic approaches,we have achieved HTMs with excellent film-forming ability,resulting in uniform and smooth films over large areas.This achievement is pivotal in ensuring the reproducibility and efficiency of photovoltaic devices.Furthermore,(ii)our investigations have led to an improvement in hole mobility within the HTMs.Through molecular engineering,such as increasing the molecular conjugation and introducing multiple SFX units,we have demonstrated enhanced charge-carrier mobility.This advancement plays a crucial role in minimizing charge recombination losses and improving the overall device efficiency.Additionally,(iii)we have explored the concept of defect passivation in SFX-based HTMs.By incorporating Lewis base structures,such as pyridine groups,we have successfully coordinated to Pb2+in the perovskite layer,resulting in a passivation of surface defects.This defect passivation contributes to better stability and enhanced device performance.Throughout our review,we highlighted the potential and opportunities achieved through these steps.The combination of enhanced film quality,improved hole mobility,and defect passivation resulted in remarkable photovoltaic performance.Our findings have demonstrated promising short-circuit current densities,open-circuit voltages,fill factors,and PCEs,with some HTMs even outperforming the widely used spiro-OMeTAD.We believe that this review will not only provide a better understanding of SFX-based HTMs but also open new avenues for enhancing the performance of organic HTMs in photovoltaic and other organic electronic devices.By providing unique perspectives and exploring different strategies,we aim to inspire ongoing advancements in photovoltaic technologies and organic electronics.Meanwhile,the success of SFX-based HTMs in improving photovoltaic device performance holds great promise for the continued development of efficient and stable photovoltaic devices in the years to come.展开更多
基金the support of the Swedish Energy Agency and Swedish Foundation for Strategic Research(SSF)for their financial supportthe China Scholarship Council(CSC)for its financial support。
文摘A new crosslinked polymer,called P65,with appropriate photo-electrochemical,opto-electronic,and thermal properties,has been designed and synthesized as an efficient,dopant-free,hole-transport material(HTM)for n-i-p type planar perovskite solar cells(PSCs).P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,90-xanthene]-30,60-diol(SFX-OH)-based monomer X65 through a freeradical polymerization reaction.The combination of a three-dimensional(3 D)SFX core unit,holetransport methoxydiphenylamine group,and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties.By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs,a power conversion efficiency(PCE)of up to 17.7%is achieved.To the best of our knowledge,this is the first time a 3 D,crosslinked,polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs.This study provides a new strategy for the future development of a 3 D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial,large-scale applications in future PSCs.
基金supported by the Swedish Research CouncilK&A Wallenberg Foundation+2 种基金Swedish Energy AgencyNational Natural Science Foundation of China(21120102036,91233201)the National Basic Research Program of China(2014CB239402)
文摘Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material （HTM） POZ6-2 using phenoxazine （POZ） as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction ofa 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-flee HTM in perovskite solar cells （PSCs） and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine （TBP） and lithium bis（trifluoromethanesulfonyl） imide （LiTFS1）. Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.
基金financial support of this work by the Swedish Research Council(2017-00935)Swedish Energy Agency and Knut and Alice Wallenberg Foundation(KAW 2016.0072)。
文摘Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.
基金supported by the National Natural Science Foundation of China(Grant No.22279059)the Fundamental Research Funds for the Central Universities(No.30921011106,30923011030)the start-up funding from the NJUST.
文摘CONSPECTUS:Organic hole-transporting materials(HTMs)are of importance in the progress of new-generation photovoltaics,notably in perovskite solar cells(PSCs),solid-state dye-sensitized solar cells(sDSCs),and organic solar cells(OSCs).These materials play a vital role in hole collection and transportation,significantly impacting the power conversion efficiency(PCE)and overall stability of photovoltaic devices.The emergence of spiro(fluorene-9,9′-xanthene)(SFX)as a novel building block for organic HTMs has gained considerable attention in the field of photovoltaics.Its facile one-pot synthetic approach,straightforward purification,and physiochemical properties over the prototype HTM spiro-OMeTAD have positioned SFX as a highly attractive alternative.In this Account,we present a comprehensive and in-depth summary of our research work,focusing on the advancements in SFX-based organic HTMs in photovoltaic devices with a particular emphasis on PSCs and sDSCs.Several key objectives of our research have been focused on exploring strategies to improve the properties of SFX-based HTMs.(i)One of the critical aspects we have addressed is the improvement of film quality.By carefully designing the molecular structure and employing suitable synthetic approaches,we have achieved HTMs with excellent film-forming ability,resulting in uniform and smooth films over large areas.This achievement is pivotal in ensuring the reproducibility and efficiency of photovoltaic devices.Furthermore,(ii)our investigations have led to an improvement in hole mobility within the HTMs.Through molecular engineering,such as increasing the molecular conjugation and introducing multiple SFX units,we have demonstrated enhanced charge-carrier mobility.This advancement plays a crucial role in minimizing charge recombination losses and improving the overall device efficiency.Additionally,(iii)we have explored the concept of defect passivation in SFX-based HTMs.By incorporating Lewis base structures,such as pyridine groups,we have successfully coordinated to Pb2+in the perovskite layer,resulting in a passivation of surface defects.This defect passivation contributes to better stability and enhanced device performance.Throughout our review,we highlighted the potential and opportunities achieved through these steps.The combination of enhanced film quality,improved hole mobility,and defect passivation resulted in remarkable photovoltaic performance.Our findings have demonstrated promising short-circuit current densities,open-circuit voltages,fill factors,and PCEs,with some HTMs even outperforming the widely used spiro-OMeTAD.We believe that this review will not only provide a better understanding of SFX-based HTMs but also open new avenues for enhancing the performance of organic HTMs in photovoltaic and other organic electronic devices.By providing unique perspectives and exploring different strategies,we aim to inspire ongoing advancements in photovoltaic technologies and organic electronics.Meanwhile,the success of SFX-based HTMs in improving photovoltaic device performance holds great promise for the continued development of efficient and stable photovoltaic devices in the years to come.
