Performance Enhancement of Interdigitated Heterojunction Solar Cells with Discotic Molecule

Abstract

Ordered interdigitated heterojunction as a promising nanostructure has attracted considerable attention due to its potential application in solar cells. However, a suitable construction to achieve effective free carrier transport in these nanostructures remains a challenge. In this study, interdigitated nanostructure was fabricated by combining vertically orientated TiO2 nanotube array with discotic liquid crystal Copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (tbCuPc). These discotic molecules were assembled as homeotropic alignment in the interdigitated nanostructure, which enhanced the carrier mobility of active layer considerably. The performance of photovoltaic cells with this interdigitated heterojunction was improved. Molecule orientation leading to charge carrier mobility enhancement was found to play a key role in improving the power conversion efficiency of the devices substantially.