Enhanced performance of P3HT-based non-fullerene polymer solar cells by optimizing film morphology using non-halogenated solvent

Abstract

Increasing research interests have been paid to developing efficient polymer solar cells by using integrating non-fullerene acceptors with poly (3-hexylthiophene) (P3HT), owing to the low-cost, promising performance and excellent stability. Here we systematically studied how processing solvents influence the overall performances of polymer solar cells using P3HT as the electron donor. It is very interesting to note that the devices processed with the non-halogenated solvent, 2-methylanisole in presence of 1-methylnaphthalene as solvent additive, exhibit reduced bimolecular and trap-assisted monomolecular recombination, facile charge extraction and enhanced charge carrier mobilities. Careful morphological investigation reveals that the optimizing crystallites, phase purity as well as nanofibrous structure is effective to the enhancement of charge generation and transport. It is also worth noting that these P3HT:O-IDTBR based devices processed with these non-halogenated solvents exhibitean impressive power conversion efficiency of 7.1% with a high fill factor of 75.09% on a device area of 0.05 cm2, and the efficiency remained 6.89% even in a device with large active layer area of 1 cm2, while also showing promising thermal stability. This study provides a new scope of processing P3HT based polymer solar cells by using non-halogenated solvents, which is compatible and has great promise for future applications.