摘要
Energy disorder is an important factor that affects charge transport,recombination,and energy loss in organic solar cells.Here,we designed a ladder-type nonfullerene acceptor and studied the critical role of energy disorder in photovoltaic performance.Taking a typical seven-member fused ring acceptor IT-4F as an example,we replaced its sp3-hybridized bridging carbon atoms and linked bulky groups with triisopropylbenzene-substituted pyrrole units.The newly synthesized acceptor 2,2′-((2Z,2′Z)-((3,9-bis(2-butyloctyl)-6,12-bis(2,4,6-triisopropylphenyl)-6,12-dihydrothieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[2,3-f]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,8-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(TBB)has a redshifted absorption spectrum with upshifted energy levels than those of IT-4F.More importantly,TBB shows more suppressed energy disorder,which leads to enhanced charge mobility and improved luminescence efficiency.Consequently,TBB-based devices obtained a power conversion efficiency of 16.2%with a relatively low nonradiative energy loss(0.22 eV),which exceeds that of IT-4F-based devices(11.5%)and is one of the top values among non-Y6 systems.This work demonstrates that rational molecular design is crucial for the suppression of energy disorder.
基金
funded by the National Natural Science Foundation of China(grant nos.22122905,22075301,and 52120105005)
H.Yao was supported by the Startup Research Fund of Southeast University(grant no.RF1028623263).
