Cooperative Effect of Solvent Additive and Solvent Vapor Annealing on High-performance Thick-film Organic Solar Cells

The solvent additive 1-naphthalene(CN)and carbon disulfide(CS2)solvent vapor annealing(SVA)were cooperatively used to optimize the thick-film active layer morphology based on the narrow band-gap small acceptors. The regulation mechanism of this strategy on the blend film morphology was revealed, and the effect of the strategy on the carrier dynamics as well as the photovoltaic performance of the device was investigated. The results show that the additive CN can effectively promote the crystallization and aggregation of the acceptor materials, and CS2 solvent vapor annealing can further improve the molecular stacking properties of donor/acceptor materials, reduce the surface roughness of the blend film, and thus obtain good nano-scale phase separation morphology. Therefore, the charge transport and recombination properties of PM6:Y6-based thick-film(300 nm)devices are effectively improved, thus obtaining the power conversion efficiency(PCE)of 15.23%, which is significantly higher than that of devices without additive treatment(PCE=11.75%)and CN-treated devices(PCE=13.48%). Moreover, this strategy can also be used to optimize the PTQ10: m-BTP-PhC6-based blend film morphology, and improve the photovoltaic performance of the devices from 13.22% to 16.92%.