Green-light wavelength-selective organic solar cells: module fabrication and crop evaluation towards agrivoltaics

Green-light wavelength-selective organic solar cells (GLWS-OSCs) pioneer novel agrivoltaics in greenhouses via transforming solar energy in the green-light region to electricity while simultaneously growing crops by utilizing the transmitted blue and red lights. However, the development of GLWS-OSCs has been stymied due to the limited availability of donors and acceptors. Herein, we investigate the combination of a cost-effective poly(3-hexylthiophene) (P3HT) donor with a fluorinated-naphthobisthiadiazole-based non-fullerene acceptor (FNTz-FA) for GLWS-OSC application. FNTz-FA shows an intense absorption band between 500 and 600 nm and a high level of chemical stability. OSCs based on P3HT and FNTz-FA with an inverted configuration are optimized to show high green-light wavelength-selective absorption and power conversion efficiency in the green-light region. Furthermore, large-scale device fabrication has been considered, leading to the development of 100 and 400 cm scale OSC modules. These modules showed sustained solar cell performance after 180 days. Photosynthetic rate measurements indicate that transmissions by the P3HT:FNTz-FA film show a non-obstructing nature and the advantage of green-light wavelength-selectivity in crop growth. Preliminary investigations on the growth of tomatoes have shown the potential of P3HT:FNTz-FA-based OSCs for agrivoltaics. These results demonstrate that GLWS-OSCs are a valid candidate to realize agrivoltaics in greenhouses for an effective utilization of solar energy.