Influence of Solvent Additive 1,8-Octanedithiol on P3HT:PCBM Solar Cells

Abstract

A facile and efficient route is developed to improve the power conversion efficiency of poly(3-hexylthiophene-2,5-diyl):[6, 6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) solar cells by processing solvent additive 1,8-octanedithiol (ODT) in the bulk heterojunction systems. The influence of ODT on polymer surface and inner morphology, crystallinity, and quantitative molecular miscibility of P3HT and PCBM is studied. The results show that ODT enhances the phase separation of P3HT and PCBM and the P3HT crystallinity, increases the solubility of PCBM in P3HT, and reduces the size of amorphous P3HT domains. A high concentration of ODT induces the formation of a PCBM enrichment surface layer, which is beneficial for the device performance.