In nonfullerene acceptor-(NFA-)based solar cells,the exciton splitting takes place at both domain interface and donor/acceptor mixture,which brings in the state of mixing phase into focus.The energetics and morphology...In nonfullerene acceptor-(NFA-)based solar cells,the exciton splitting takes place at both domain interface and donor/acceptor mixture,which brings in the state of mixing phase into focus.The energetics and morphology are key parameters dictating the charge generation,diffusion,and recombination.It is revealed that tailoringthe electronic properties of the mixing region by doping with larger-bandgap components could reduce the density of state but elevate the filling state level,leading to improved open-circuit voltage(V_(OC))and reduced recombination.The monomolecular and bimolecular recombinations are shown to be intercorrelated,which show a Gaussian-like relationship with V_(OC) and linear relationship with short-circuit current density(JSC)and fill factor(FF).The kinetics of hole transfer and exciton diffusion scale with JSC similarly,indicating the carrier generation in mixing region and crystalline domain are equally important.From the morphology perspective,the crystalline order could contribute to V_(OC) improvement,and the fibrillar structure strongly affects the FF.These observations highlight the importance of the mixing region and its connection with crystalline domains and point out the design rules to optimize the mixing phase structure,which is an effective approach to further improve device performance.展开更多
基金This work was financially supported by the grant from the National Natural Science Foundation of China(Grant Nos.51973110,21734009,and 21905102)the National Key R&D Program of China under grant nos.2020YFB1505500 and 2020YFB1505502+3 种基金the Program of Shanghai Science and Technology Commission science and technology innovation action plan(20ZR1426200,20511103800,20511103802,and 20511103803)the Natural Science Foundation of Shandong Province,China(ZR2019LFG005)the Key Research Project of Shandong Province under grant no.2020CXGC010403beamline 7.3.3 and 11.0.1.2 at the Advanced Light Source,Lawrence Berkeley National Laboratory,which was supported by the DOE,Office of Science,and Office of Basic Energy Sciences.
文摘In nonfullerene acceptor-(NFA-)based solar cells,the exciton splitting takes place at both domain interface and donor/acceptor mixture,which brings in the state of mixing phase into focus.The energetics and morphology are key parameters dictating the charge generation,diffusion,and recombination.It is revealed that tailoringthe electronic properties of the mixing region by doping with larger-bandgap components could reduce the density of state but elevate the filling state level,leading to improved open-circuit voltage(V_(OC))and reduced recombination.The monomolecular and bimolecular recombinations are shown to be intercorrelated,which show a Gaussian-like relationship with V_(OC) and linear relationship with short-circuit current density(JSC)and fill factor(FF).The kinetics of hole transfer and exciton diffusion scale with JSC similarly,indicating the carrier generation in mixing region and crystalline domain are equally important.From the morphology perspective,the crystalline order could contribute to V_(OC) improvement,and the fibrillar structure strongly affects the FF.These observations highlight the importance of the mixing region and its connection with crystalline domains and point out the design rules to optimize the mixing phase structure,which is an effective approach to further improve device performance.
