Improving the Efficiency of Organic Solar Cells by Introducing Perylene Diimide Derivative as Third Component and Individually Dissolving Donor/Acceptor.

A perylene diimide (PDI) derivative was used as the third component to prepare high-efficiency ternary organic solar cells (OSCs). PDI derivatives usually bear a wide bandgap and a long exciton diffusion length, which could be helpful to promote the device efficiency and still retain a high open-circuit voltage (Voc ). Compared with the binary OSC, the photovoltaic performance improved. Further changing the method for preparing the processing solutions from dissolving the polymer donor and small-molecule acceptor ITTC together to dissolving them individually, molecular packing in the deposited active layer could be adjusted and the short-circuit current density could be increased. As a result, the final device efficiency in such OSCs achieved 12.29 % power conversion efficiency (PCE) with a high Voc of 0.93 V. When using the PDI derivative as the third component to D18 : BTP-eC9-based OSCs, a high PCE of 17.38 % was obtained, which is the best one among photovoltaic devices employing PDI derivatives.