Solution-Processed Organic Photovoltaics Based on Indoline Dye Molecules Developed in Dye-Sensitized Solar Cells

A donor-acceptor (D-A) type indoline dye, D149, was used as an electron donor in solution-processed organic solar cells (OSCs). For bulk-heterojunction (BHJ) type OSCs with PC(70)BM as electron acceptor, the power conversion efficiency (PCE) is sensitive to the amount of D149 in the D149/PC(70)BM blend film. When the concentration of D149 in the blend film was as low as 5%, the highest PCE of up to 1.29%, together with a short-circuit current density (Jsc) of 4.58 mA·cm(−2), an open-circuit voltage (Voc) of 0.90 V and a fill factor (FF) of 0.31, was achieved. In order to improve the PCE of D149-based OSCs, a bilayer-heterojunction configuration with C(70) as electron acceptor has been employed. By optimizing the thickness of the D149 layer and varying the electron- and hole-transport layers, a highest PCE of up to 2.28% with a Jsc of 4.38 mA·cm(−2), a Voc of 0.77 V, and an FF of 0.62 was achieved under AM 1.5G solar illumination (100 mW·cm(−2)).