Controlling Green-Solvent Processability via the Dipole Moment of Nonfullerene Acceptor in Green-Light Wavelength-Selective Organic Solar Cells.

In pursuit of agrivoltaics applications in greenhouses, green-light wavelength-selective organic solar cells (GLWS-OSCs) have emerged as a promising technology that enables simultaneous energy harvesting and crop cultivation. For their practical large-scale fabrication, the development of environmentally benign processing methods, along with achieving high photovoltaic performance, is essential. Herein, to investigate the impact of the dipole moment of nonfullerene acceptors on their suitability for green-solvent processing, we developed a symmetric acceptor, BTz-TT-FA, possessing an intrinsically low dipole moment. BTz-TT-FA shows green-light absorption with a maximum absorption wavelength at 531 nm. The ionization potential and electron affinity were determined to be 5.63 and 3.02 eV, respectively, indicating that BTz-TT-FA possesses appropriate energy levels as an acceptor for use with poly(3-hexylthiophene) (P3HT) as the donor. The P3HT:BTz-TT-FA film shows a high green-light wavelength-selectivity factor of 0.77, thereby maintaining an adequate photosynthetic rate in strawberries. The P3HT:BTz-TT-FA-based OSCs showed superior photovoltaic performance, achieving higher power conversion efficiency under p-xylene-processed conditions, compared to those processed with chlorobenzene. The dependence of the process solvent on film crystallinity, morphology, and miscibility was investigated. These findings highlight the critical role of dipole moment in facilitating green-solvent processing and demonstrate a promising pathway toward the development of sustainable GLWS-OSCs.