Phosphorescent molecular metal complexes in heterojunction solar cells

Bulk heterojunction (BHJ) solar cells have been developed intensively over the last two decades due to the cheap, flexible devices which may be obtained although their efficiency is below that of other emerging solar cell technologies such as dye-sensitized and perovskite solar cells. Molecular organometallic phosphors are noted for their triplet harvesting ability which has produced highly efficient organic light-emitting devices however triplet harvesting presents an equally appealing route to improve the efficiency of BHJ devices. The results of studies using molecular phosphors as dopants in very small loadings can yield large increases in short circuit currents and power conversion efficiency and demonstrate that improvements in solar cell performance may be obtained by this approach.