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 remains 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 enhance the photovoltaic properties of BHJ devices. The results of studies which have used the triplet sensitizing properties of metal complexes towards increasing the efficiency of BHJ solar cells are presented here. By using small quantities of molecular phosphors as dopants, large improvements in short circuit current and power conversion efficiency may be obtained. (C) 2017 Elsevier Ltd. All rights reserved.