Improving device performance of MAPbI 3 photovoltaic cells by manipulating the crystal orientation of tetragonal perovskites.

The properties of CH ₃ NH ₃ PbI ₃ (MAPbI ₃ ) crystalline thin films and the device performance of highly efficient MAPbI ₃ photovoltaic cells are investigated by varying the temperature of the antisolvent from 20 °C to 50 °C during the washing enhanced nucleation (WEN) process. The surface, structural, optoelectronic and defect properties of the perovskite thin films are characterized through atomic-force microscopy, X-ray diffractometry and photoluminescence spectrometry. The experimental results show that changing the temperature of the antisolvent during the WEN process can manipulate the MAPbI ₃ crystalline thin films from the (110)-(002) complex phase to a (002) preferred phase. It is noted that the highest power conversion efficient of the inverted MAPbI ₃ photovoltaic cells is 19.30%, mainly due to the increased carrier collection efficiency and reduced carrier recombination when the temperature of the antisolvent is 30 °C.
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