Tin instead of aluminum as a back electrode in P3HT:PC₇₁BM organic solar cells

Abstract

In the present work, a thin film of tin (Sn) metal, instead of aluminum, was deposited as a back electrode, using thermal evaporation, for fabricating organic solar cell composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM). The effect of post-thermal annealing on performance parameters of the solar cell has been investigated at low temperatures (suitable for organic solar cells) up to 180 oC. In addition, effect of thermal annealing on morphological (using scanning electron microscopy) and electrical properties (using Hall Effect setup) of the Sn thin films was reported and discussed here. The obtained minor effect of the thermal annealing on morphological and electrical properties of Sn thin films is offset by an improvement in the performance parameters of solar cells after post-annealing at 160 oC. The present study shows good electrical properties of the Sn thin films which are comparable with those of aluminum thin films.