Benzothiadiazole-Based Fused-Ring Electron Acceptors for Green-Light Wavelength-Selective Organic Solar Cells

Abstract

Organic solar cells (OSCs) have been anticipated as a promising renewable energy source. In particular, green-light wavelength-selective (GLWS) OSCs have the potential to convert green light into electricity while allowing blue and red light to support crop growth, making them suitable for greenhouse integration. To realize GLWS OSCs, P3HT has been selected as a suitable GLWS donor. However, compatible GLWS nonfullerene acceptors (NFAs) compatible for P3HT remain limited. Here, we designed and synthesized new fused-ring NFAs, TPBTz-RD and i-TPBTz-RD, incorporating a benzothiadiazole (BTz) unit into their conjugated systems. These NFAs exhibited sharp absorption bands in the green-light wavelength region due to their rigid fused-ring skeletons. Inverted OSCs fabricated with P3HT and TPBTz-RD as the active layer showed a moderate power conversion efficiency (PCE) of 2.12%. The GLWS factor (S_G) and the PCEs in the green-light region (PCE-GR) of the OSCs were determined to be 0.85 and 3.5%, respectively. The P3HT:TPBTz-RD blend film showed enhanced photosynthetic rates in strawberry leaves compared to those under a referential P3HT:SNTz-RD blend film. These results suggest that the fine-tuning of absorption band is important to develop GLWS OSCs for agrivoltaics.