Interfacial modification of various alkali metal cations in perovskite solar cells and their influence on photovoltaic performance

The electron transport layer (ETL) between the perovskite material and cathode plays an important role in planar perovskite solar cells. In this study, an alkali metal salt solution was be used to modify the surface of the SnO2 electron transport layer to optimize electron transport. The I-V characteristic measurements and UV-Vis spectroscopy were used to investigate whether introducing the interface modification can increase the electron coupling and effectively extract the energy lever of electrons. The results indicated that the interfacial modification could reduce the trap density of states and increase the mobility of the SnO2 thin films. The efficient defect passivation significantly suppressed the recombination at the SnO2/perovskite interface. This method aims at passivation using simple and low-cost inorganic material poles.