Green solvent-processed organic solar cells based on a low cost polymer donor and a small molecule acceptor

Abstract

Low cost photovoltaic materials and green solvent processing are important issues for commercial application of organic solar cells (OSCs). Here, we fabricated high-performance OSCs based on the low-cost conjugated polymer PTQ10 as a donor and the small molecule n-type organic semiconductor HO-IDIC-2F as an acceptor, using non-halogen tetrahydrofuran (THF) as the processing solvent. The power conversion efficiency (PCE) of the as-cast OSCs reached 12.20%, which is comparable with the ones processed with chloroform (CF) (12.43%). Thermal stability of the active layer was also studied by thermal treatment at 100 °C for 8 hours. As a result, the active layer morphology remained unchanged and the PCE of the devices still reached 12.13%, indicating a good thermal-stability of the PTQ10:HO-IDIC-2F blend film. As is commonly known, for OSCs fabricated on larger scales, the layer-by-layer (LL) method generally provides more advantages than the traditional D–A blend solution-processing method. Therefore, to test the compatibility of the THF solvent in the LL method, we fabricated blade-coated LL devices with THF as a single type of solvent for both the donor and acceptor, and the PCE could reach up to 11.85%. The surprisingly high performance of the blade-coated OSC based on the green solvent indicates that PTQ10 is a promising donor to be processed in green solvent for LL technology in the future.