Surface modification of SnO2 blocking layers for hysteresis elimination of MAPbI3 photovoltaics

We have demonstrated a two-step wet-chemical route to prepare dense a SnO 2 blocking layer (BL) for boosting efficaciously the optoelectronic performance of mesoporous-TiO 2 based perovskite solar cells (PSCs). Through SnCl 4 water-bath for moderate time, the surface features of SnO 2 BL are availably optimized and recombination loss of the devices is perceptibly suppressed. The influence of bath-time upon the microstructures and photoelectronic properties of SnO 2 BL and photovoltaic characteristics of the corresponding PSCs , has been discussed detailedly. Deep-going explorations on charge dynamics confirm that SnCl 4 bath would facilitate charge transport, hinder charge accumulation and inhibit nonradiative recombination. Upon the basis of surface decoration of SnO 2 , we improve the open-circuit photovoltage from 1.02 V of initial cell to 1.06 V, and achieve a maximum photovoltaic efficiency of 17.14% and null hysteresis. Accordingly, the device with large area (1.0 cm 2 ) based on modified SnO 2 have higher PCE of 14.35% and weaker hysteresis index of 0.019 than its unmodified SnO 2 courtpart.