Band gap aligned conducting interface modifier enhances the performance of thermal stable polymer-TiO2 nanorod solar cell

Abstract

In this paper, we show that the poly(3-hexyl-thiophene)/TiO2 nanorod hybrid material is more thermally stable than the poly(3-hexyl-thiophene)/[6,6]-phenyl C61-bntyric acid methyl ester (P3HT/PCBM) hybrid material. A metal free conducting interface modifier of oligo-3-hexyl thiophene carboxylic acid (oligo-3HT-COOH) has been synthesized that exhibits aligned band gap for the P3HT/TiO2 hybrid. The conducting modifier shows an increase in power conversion efficiency of 4.8 times over an insulating modifier of oleic acid and 2.2 folds improvement over small molecule modifier of pyridine. These increases are due to a reduced recombination rate (42 μs carrier life time) and fast electron injection time of 0.24 ps. This interface modifier makes thermally stable organic-inorganic hybrid materials useful for fabrication of all solution processable solar cells.