High-Performance Semitransparent Ternary Organic Solar Cells

Semitransparent organic solar cells (STOSCs) are ideal candidates for building-integrated photovoltaics. Power conversion efficiency (PCE) is one of the most important parameters of STOSCs, which is typically limited by the intrinsic narrow absorption of thin active layer. Ternary structure is demonstrated as an efficient approach to broaden the light absorption and manipulate the morphology, thus leading to improved PCEs by introducing a third component into the binary system. However, STOSCs based on ternary systems are rarely studied. In this contribution, semitransparent ternary solar cells are fabricated using a wide-bandgap (E-g = 2.10 eV) polymer donor, PBT1-S, as the third component. It is found that the addition of a small amount of PBT1-S to PTB7-Th:PC71BM blend has a negligible influence on its average visible transmittance (AVT) and color perception. A PCE of 9.2% is achieved for the champion ternary device with 20% AVT, which is one of the highest values for STOSCs. The results indicate that ternary structure is a promising approach for the fabrication of high-performance STOSCs.