A perylenediimide (PDI)-based small molecular (SM) acceptor with both an extended π-conjugation and a three dimensional structure concurrently is critical for achieving high performance PDI-based fullerene-free organic solar cells (OSCs). In this work, we designed and synthesized a novel PDI-based SM acceptor possessing both characteristics by fusing PDI units with a spiro core of 4,4’-spirobi[cyclopenta[2,1-b;3,4-b’]dithiophene(SCPDT) through the -position of the thiophene rings. An enhanced strong absorption in the range of 350–520 nm and arisen LUMO energy level of FSP was observed, compared with previous reported acceptor SCPDT-PDI4, in which the PDI units and SCPDT are not fused. OSCs based on PTB7-Th donor and FSP acceptor were fabricated and achieved a power conversion efficiency of up to 8.89% with DPE as an additive. Efficient and complementary photo absorption, favorable phase separation and balanced carrier mobilites in the blend film account for the high photovoltaic performance. This study offers an effective strategy to design high performance PDI-based acceptors.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank the National Basic Research Program of China (Fundamental Studies of Perovskite Solar Cells 2015CB932200), National Natural Science Foundation of China (Nos.51373076, 61605075, 91433118), and SICAM Scholarship by Jiangsu National Synergetic Innovation Center for Advanced Materials for financial support. Q.Z. acknowledges financial support from AcRF Tier 1 (RG8/16, RG133/14 and RG 13/15), Singapore.