Mixed solvents for reproducible photovoltaic bulk heterojunctions

摘要

Most efficient polymer solar cells are usually fabricated from toxic organic sol- vents, such as chloroform, chlorobenzene, or dichlorobenzene (ODCB). Here, we demonstrate a power conversion efficiency of 4.5% in solar cells with a new blue polymer poly[2,3-bis-(3- octyloxyphenyl) quinoxaline - 5, 8 - diyl - alt - thiophene-2, 5 - diyl] (TQ1) mixed with processed from mixed solvents of toluene and ODCB in a ratio of 9: 1. Decreasing the con- tent of ODCB makes device processing more compatible with the environment for large scale production, with 10% reduction of photocurrent compared to devices from pure ODCB under optimized conditions. In addition, less variation of photocurrent is obtained in solar cells pro- cessed from mixed solvents than from pure ODCB due to varying nanostructure in the blends, which is also critical for production.