High-efficiency and stable perovskite solar cells prepared using chlorobenzene/acetonitrile anti-solvent.

Preparing high-quality perovskite film with large grain size and less trap states is of vital importance in boosting the efficiency and stability of perovskite solar cells (PSCs). However, it's still difficult to obtain perfect MAPbI3 films by anti-solvent treatment so far because of the small grain size, pinholes and numerous defects in perovskite layers. Herein, the acetonitrile (ACN) was introduced into the chlorobenzene (CB) anti-solvent to modify the MAPbI3 active layer. The results show that the ACN could control the ratio of the DMSO in MAI-PbI2-DMSO intermediate phase film effectively and thus manipulate the formation of MAPbI3 film. Relatively high-quality perovskite films with larger grain size were obtained when we adding 6% v/v ACN into CB anti-solvent. Based on the ACN-modified MAPbI3 film, the n-i-p planar device with the structure of FTO/SnO2/MAPbI3/spiro-OMeTAD/Ag yields the best power conversion efficiency (PCE) of 18.9%. It exhibited an enhancement of 16.6% in efficiency compared with the PCE of 16.2% for the control device. In addition, the device based on ACN-modified MAPbI3 also presents improved stability in air atmosphere.