Highly efficient polycarbazole-based organic photovoltaic devices

We combined experimental and computational approaches to tune the thickness of the films in poly($N\text{-}{9}^{\prime }$ -heptadecanyl-2,7-carbazole-alt-5,5-($4^{\prime },7^{\prime }$ -di-2-thienyl-$2^{\prime },1^{\prime },3^{\prime }$ -benzothiadiazole) (PCDTBT)-based organic solar cells to maximize the solar absorption by the active layer. High power-conversion efficiencies of 5.2% and 5.7% were obtained on PCDTBT-based solar cells when using [6,6]-phenyl ${\text{C}}_{61}$ -butyric acid methyl ester $\left({\text{PC}}_{60}\text{BM}\right)$ and [6,6]-phenyl ${\text{C}}_{71}$ -butyric acid methyl ester $\left({\text{PC}}_{70}\text{BM}\right)$ as the electron acceptor, respectively. The cells are designed to have an active area of $1.0{\text{cm}}^2$ , which is among the largest organic solar cells in the literature, while maintaining a low series resistance of $5\Omega {\text{cm}}^2$ .