Triplet excitons: improving exciton diffusion length for enhanced organic photovoltaics

Abstract

A short exciton diffusion length (L_D) is one of the main factors limiting the final power conversion efficiency (PCE) of organic photovoltaics (OPV). Aiming at overcoming this barrier, there have been studies on the use of longer-lived triplet excitons, which can be introduced either through triplet sensitization by doping or through the use of donor materials containing heavy atoms that allow for intersystem crossing (ISC). This review focuses on how these systems have been shown to increase L_D, leading to increased PCEs, and discusses challenges associated with the use of triplet materials.