Mechanism and effect of γ-butyrolactone solvent vapor post-annealing on the performance of a mesoporous perovskite solar cell

In this paper, γ-butyrolactone (GBL) solvent vapor post-annealing (SVPA) on CH(3)NH(3)PbI(3) thin films is reported, aiming to improve the complete transformation of PbI(2) and increase the grain size of the CH(3)NH(3)PbI(3) crystal, thus boosting the performance of mesoporous CH(3)NH(3)PbI(3) perovskite solar cells (PSCs). The influence of GBL SVPA on the microstructure of perovskite layers and performance of PSCs was studied. The short circuit current density (J(sc)) of the devices significantly increased, yielding a high efficiency of 16.58%, which was 27.05% higher than that of thermally annealed films. A model was derived to explain the effect of GBL SVPA on PSCs. The perovskite films prepared by this method present several advantages such as complete transformation of PbI(2) to CH(3)NH(3)PbI(3), high crystallinity, large grain size, and fewer grain boundaries than those prepared without GBL SVPA. This improvement is beneficial for charge dissociation and transport in hybrid photovoltaic devices.