Hybrid Nonfused Electron Acceptors with Perylene Diimide Pendants for Organic Solar Cells

Abstract

In this work, we have designed and synthesized two hybrid nonfused electron acceptors with a perylene diimide pendant (denoted TPDICPBI and TPDICPBI-C6), where TPDICPBI featured a rigid linker, whereas TPDICPBI-C6 incorporated a flexible linker. It was realized via synthesizing the perylene diimidecontaining dibromine compounds and performing the Stille reaction followed by Knoevenagel condensation. TPDICPBI with the rigid linker exhibits a much higher glass transition temperature (T g , 208 °C) compared to that (92 °C) of TPDICPBI-C6 with the flexible linker, which can be attributed to the rigid linker that limits the motion of both TPDIC and the PBI unit. Then, the two electron acceptors were applied to organic solar cells (OSCs). Devices based on TPDICPBI gave a power conversion efficiency (PCE) of 9.91%, and TPDICPBI-C6-based devices showed a reduced PCE of 8.39%. Morphological characterization revealed that both TPDICPBI and TPDICPBI-C6 exhibited overall weak aggregation/crystallization properties. The results suggest that by employing rational molecular engineering to adjust the aggregation/crystallization properties of TPDICPBI, the hybrid electron acceptors will give satisfactory photovoltaic performance.