Highly efficient organic photovoltaics via heteroatom doped carbon nanomaterials

Abstract

Organic photovoltaic cells (OPVs) present the potential to change the market of energy production. They have garnered advantages of low-cost process, mechanical flexibility and light weight. In recent years, the power conversion efficiency (PCE) of OPVs has steadily improved as high as 9.2%. Despite promising progress in device performance, PCE have to be enhanced for the commercialization. One of the crucial challenges for the high device performance is the efficient charge transport at the polymer/fullerene active layers with bulk heterojunction (BHJ) structure. In this study, we demonstrate an ideal active layer employing various types of carbon nanotubes (CNTs), as they have excellent carrier mobility, mechanical flexibility, and compatibility with the solution process. Unlike previously reported OPVs with CNTs significantly degraded the device performance than those without CNTs. Without charge selectivity, any small proportion of metallic CNTs present may build up undesired pathways for electron-hole recombination. Moreover, inhomogeneously dispersed CNT aggregates give rise to a fatal device short circuit. we present the remarkable device performance enhancement in BHJ solar cells employing N-doped (N-CNT), B-doped CNTs (B-CNT), quantum dot nanoparticle decorated CNTs (QD:CNT) or metal nanoparticle bound CNTs (Me:CNT) as highly selective electron- or hole-transport enhancement materials. We also emphasize that this study offers a general route to address the efficient charge transport for other organic optoelectronics, such as organic light-emitting diodes, organic transistors, and organic laser diodes.