Polythiophene solar cells processed from non-halogenated solvent with 15.68% efficiency

Polythiophenes (PTs) are prospective polymer donors for large-scale manufacturing and industrialization owing to their simple structures and low synthetic cost. However, the fabrication of PT solar cells depends on highly toxic chlorinated solvents, and less research has been done on the use of more environmentally friendly non-halogenated solvents. Herein, highly efficient PT solar cells based on top-performance polythiophene, P5TCN-F25, processed from a non-halogenated solvent are reported by delicate aggregation control. A power conversion efficiency of up to 15.68% was achieved by depositing the active layer from a hot o -xylene solution, which is the record efficiency of non-halogenated processed PT solar cells up to date. The appropriate solution temperature is beneficial to the formation of ordered polymer stacking and desirable phase separation size, which thereby contributes to enhanced charge transfer efficiency, more balanced hole electron mobility, and reduced trap-assisted recombination. These results provide valuable implications for improving the efficiency of PT solar cells via environmentally-friendly processing.