Utilizing 3,4-ethylenedioxythiophene (EDOT)-bridged non-fullerene acceptors for efficient organic solar cells

• 作者: Sung Jae Jeon Young Hoon Kim Ie Na Kim Nam Gyu Yang Ji Hee Yun Doo Kyung Moon
• 来源期刊: 能源化学
• 年，卷（期）: 2022,（2）
• 页码范围: 194-204
• 页数: 11页
• 语种: 英文

摘要

A rational design of efficient low-band-gap non-fullerene acceptors (NFAs) for high-performance organic solar cells (OSCs) remains challenging;the main constraint being the decrease in the energy level of the lowest unoccupied molecular orbitals (LUMOs) as the bandgap of A-D-A-type NFAs decrease.Therefore,the short current density (Jsc) and open-circuit voltage (Voc) result in a trade-off relationship,making it difficult to obtain efficient OSCs.Herein,three NFAs (IFL-ED-4F,IDT-ED-4F,and IDTT-ED-2F) were synthe-sized to address the above-mentioned issue by introducing 3,4-ethylenedioxythiophene (EDOT) as a n-bridge.These NFAs exhibit relatively low bandgaps (1.67,1.42,and 1.49 eV,respectively) and upshifted LUMO levels (-3.88,-3.84,and-3.81 eV,respectively) compared with most reported low-band-gap NFAs.Consequently,the photovoltaic devices based on IDT-ED-4F blended with a PBDB-T donor polymer showed the best power conversion efficiency (PCE) of 10.4％ with a high Jsc of 22.1 mA cm-2 and Voc of 0.884 V among the examined NFAs.In contrast,IDTIT-ED-4F,which was designed with an asymmetric structure of the D-π-A type,showed the lowest efficiency of 1.5％ owing to the poor morphology and charge transport properties of the binary blend.However,when this was introduced as the third compo-nent of the PM6:BTP-BO-4Cl,complementary absorption and cascade energy-level alignment between the two substances could be achieved.Surprisingly,the IDTT-ED-4F-based ternary blend device not only improved the Jsc and Voo but also achieved a PCE of 15.2％,which is approximately 5.3％ higher than that of the reference device with a minimized energy loss of 0.488 eV.In addition,the universality of IDTT-ED-2F as a third component was effectively demonstrated in other photoactive systems,specifically,PM6:BTP-eC9 and PTB7-Th:IEICO-4F.This work facilitates a better understanding of the structure-property rela-tionship for utilizing efficient EDOT-bridged NFAs in high-performance OSC applications.