Efficient organic solar cells achieved at a low energy loss.

Highlights from the article: Organic photovoltaics (OPVs) have attracted much attention because of the advantages in low-cost and large-area fabrication and the great potentials in achieving flexible and semi-transparent devices [1]. For the traditional bulk-heterojunction OPVs applying fullerene derivatives as the electron acceptors, the E SB loss sb s are always higher than 0.6 eV, which limits the power conversion efficiencies (PCEs) less than 12% [4]. With the rapid development of fused-ring electron acceptors especially with an acceptor (A)-donor (D)-acceptor (A) arrangement [5], PCEs of OPV devices quickly surpassed 12% and even reached 16% in a very short period [6], [7], [8], [9], [10], in quite a few of which the E SB loss sb s are less than 0.6 eV. Although it is common for inorganic or perovskite solar cells, high-performance OPVs with the E SB loss sb s less than 0.5 eV are quite rare up to date, which means that the E SB loss sb is still the key factor that limits the photovoltaic efficiency of the OPV technique.