Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting b...Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting bandgaps of the front and back cells,current matching,thickness,and recombination layer optimization)often result in lower PCEs than are observed in single-junction devices.In this study,we analyze the influence of front cell and back cell bandgaps and use transfer matrix modeling to rationally design and optimize effective tandem solar cell structures before actual device fabrication.Our approach allows us to estimate tandem device parameters based on known absorption coefficients and open-circuit voltages of different active layer materials and design devices without wasting valuable time and materials.Using this approach,we have investigated a series of wide bandgap,high voltage photovoltaic polymers as front cells in tandem devices with PTB7-Th as a back cell.In this way,we have been able to demonstrate tandem devices with PCE of up to 12.8%with minimal consumption of valuable photoactive materials in tandem device optimization.This value represents one of the highest PCE values to date for fullerene-based tandem solar cells.展开更多
Since the world-record power conversion efficiency of 15.7%was achieved for organic solar cells(OSCs)in 2019,the newly developed non-fullerene acceptor(NFA)Y6 with an A-DA′D-A structure(A denotes an electron-acceptin...Since the world-record power conversion efficiency of 15.7%was achieved for organic solar cells(OSCs)in 2019,the newly developed non-fullerene acceptor(NFA)Y6 with an A-DA′D-A structure(A denotes an electron-accepting moiety,D denotes an electron-donating moiety)has attracted increasing attention.Subsequently,many new A-DA′D-A NFAs have been designed and synthesized,and the A-DA′D-A NFAs have played a significant role in the development of high-performance non-fullerene organic solar cells(NF-OSCs).Compared with the classical A-D-A-type acceptors,A-DA′D-A NFAs contain an electrondeficient core(such as benzothiadiazole(BT),benzotriazole(BTA),quinoxaline(Qx),or their derivatives)in the ladder-type fused rings to fine-tune the energy levels,broaden light absorption and achieve higher electron mobility of the NFAs.This review emphasizes the recent progress on these emerging A-DA′D-A(including Y-series)NFAs.The synthetic methods of DA′D-fused rings are introduced.The relationships between the chemical structure of the A-DA′D-A NFAs and the photovoltaic performance of the corresponding OSCs are summarized and discussed.Finally,issues and prospects for further improving photovoltaic performance of the OSCs are also proposed.展开更多
基金This study was supported by the National Research Foundation of Korea(2017R1C1B1010627)the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea Government Ministry of Trade,Industry and Energy(MTIE)(20163030013900,20183010013900)This study was supported by the Technology Development Program to solve climate changes of the National Research Foundation(NRF)funded by theMinistry of Science,ICT and Future Planning(NRF-2015M1A2A2057506,2019M1A2A2065614).
文摘Tandem device architectures offer a route to greatly increase the maximum possible power conversion efficiencies(PCEs)of polymer solar cells,however,the complexity of tandem cell device fabrication(such as selecting bandgaps of the front and back cells,current matching,thickness,and recombination layer optimization)often result in lower PCEs than are observed in single-junction devices.In this study,we analyze the influence of front cell and back cell bandgaps and use transfer matrix modeling to rationally design and optimize effective tandem solar cell structures before actual device fabrication.Our approach allows us to estimate tandem device parameters based on known absorption coefficients and open-circuit voltages of different active layer materials and design devices without wasting valuable time and materials.Using this approach,we have investigated a series of wide bandgap,high voltage photovoltaic polymers as front cells in tandem devices with PTB7-Th as a back cell.In this way,we have been able to demonstrate tandem devices with PCE of up to 12.8%with minimal consumption of valuable photoactive materials in tandem device optimization.This value represents one of the highest PCE values to date for fullerene-based tandem solar cells.
基金supported by the National Natural Science Foundation of China(21875286)the National Key Research and Development Program of China(2017YFA0206600)+1 种基金the Science Fund for Distinguished Young Scholars of Hunan Province(2017JJ1029)the Natural Sciences and Engineering Research Council of Canada。
文摘Since the world-record power conversion efficiency of 15.7%was achieved for organic solar cells(OSCs)in 2019,the newly developed non-fullerene acceptor(NFA)Y6 with an A-DA′D-A structure(A denotes an electron-accepting moiety,D denotes an electron-donating moiety)has attracted increasing attention.Subsequently,many new A-DA′D-A NFAs have been designed and synthesized,and the A-DA′D-A NFAs have played a significant role in the development of high-performance non-fullerene organic solar cells(NF-OSCs).Compared with the classical A-D-A-type acceptors,A-DA′D-A NFAs contain an electrondeficient core(such as benzothiadiazole(BT),benzotriazole(BTA),quinoxaline(Qx),or their derivatives)in the ladder-type fused rings to fine-tune the energy levels,broaden light absorption and achieve higher electron mobility of the NFAs.This review emphasizes the recent progress on these emerging A-DA′D-A(including Y-series)NFAs.The synthetic methods of DA′D-fused rings are introduced.The relationships between the chemical structure of the A-DA′D-A NFAs and the photovoltaic performance of the corresponding OSCs are summarized and discussed.Finally,issues and prospects for further improving photovoltaic performance of the OSCs are also proposed.
