Improved charge separation and transport efficiency in poly(3-hexylthiophene)–TiO2 nanorod bulk heterojunction solar cells

Abstract

In this article, we have fabricated photovoltaic devices based on the poly(3-hexylthiophene)–TiO2nanorod bulk heterojunction. The microscopic mechanisms of charge separation and charge transport in the poly(3-hexylthiophene)–TiO2nanorod nanocomposites have been investigated by photoluminescence quenching, time-resolved photoluminescence spectroscopy, and time-of-flight mobility measurements. Charge separation and transport efficiency can be improved by adding an adequate amount of TiO2nanorods in polymer. In addition, the device performance can be further enhanced by thermal annealing or removal of insulating surfactant in the hybrid, giving an optimized device performance of a short circuit current density of 2.62 mA cm−2, an open circuit voltage of 0.69 V, a fill factor of 0.63 under simulated A.M. 1.5 illumination (100 mW cm−2). The corresponding power conversion efficiency under 1 sun is about 1.14%.