Performance Improvement of Bulk Heterojunction Organic Photovoltaic Cell by Addition of a Hole Transport Material

Abstract

A novel photovoltaic cell with an active layer of poly(phenyleneethynylene) (PPE)/C60/N,N′-diphenyl-N,N′-di-(m-tolyl)-p-benzidine (TPD) is designed. In the active layer, PPE is the major component; C60 and TPD are the minor ones. Compared with a control BHJ device based on PPE/C60, the short circuit current density Jsc is increased by 1 order of magnitude, and the whole device performance is increased greatly, however the open circuit voltage Voc is largely decreased. The possible mechanism of the improved performance may be as follows: In the PPE/C60/TPD device, PPE, C60, and TPD serve as the energy harvesting material, the electron transport material, and the hole transport material, respectively. As the TPD and C60 are spatially separated by PPE, the charge recombination is effectively retarded.