Highly efficient perovskite solar cells fabricated by simplified one-step deposition method with non-halogenated anti-solvents

Organic-inorganic hybrid halide perovskite solar cells (PVSCs) are promising low-cost photovoltaic technologies with their impressive power conversion efficiency (PCE) and low temperature solution processability. A large amount of toxic solvents has been used in the fabrication of PVSCs, especially the halogenated solvent chlorobenzene (CB) which is heavily applied as the anti-solvent of the perovskite layer and the solvent of electron transport layer (ETL) in p-i-n type PVSCs. Herein, we replace CB with non-halogenated solvents, o-xylene (OXY) and 1,2,4-trimethylbenzene (TMB), and introduce perovskite-fullerene graded heterojunction (GHJ) to engineer efficient perovskite layer and ETL. By merging two deposition processes of perovskite layer and ETL, high efficiencies of 16.82% and 16.88% are obtained for PVSCs with OXY and TMB, respectively. The PVSCs prepared from non-halogenated solvents engineering demonstrate superior performance over their CB counterparts of which the PCE is 14.45%, mainly due to much larger grains, improved electron collection and reduced recombination loss in the former PVSCs. These results indicate both OXY and TMB are potential alternative non-halogenated solvents for PVSCs manufacturing. Moreover, since two separate deposition processes are merged, the process becomes easier and simpler, leading to reduction of fabrication costs.