Electrical and morphological variations with sintering temperature of electron transport layer in perovskite solar cell

The typical PSCs essentially made up of electron transporting material (compact and mesoporous), perovskite absorber layer and hole transporting material. The compact TiO2 primary function is allow the movement of photogenerated electron to the device circuit from the active layer and to block the photogenerated holes from recombination at TCO substrate. Mesoporous TiO2 mainly functions to receive the photogenerated charge from the perovskite absorber and enable thicker formation of perovskite absorber due to the voids in the TiO2 mesoscopic framework. Many studies have implemented 500 ℃ as the standard in sintering the TiO2 layer. However, the effects of sintering temperature of ETL TiO2 have never been systematically described in terms of morphology and photoelectrochemical properties. In this manuscript, we have studied the morphological and photoelectrochemical properties of ETM TiO2 thin film prepared at different sintering temperature. Spin coated TiO2 layers were examined using X-ray Diffraction for crystal structure and phase identification, FESEM for morphological analysis, UV-Vis Spectroscopy for optical absorbance and transmittance of light and PEC test for LSV, EIS and TPC analyses. Surface roughness was not a major influencing factor of photocurrent density rather than the anatase phase of the TiO2 thin film is more important. It was revealed that at 500 ℃, the TiO2 thin film possess the highest photocurrent density with good stability and lowest charge transfer and series resistance. Higher sintering temperature of 550 ℃, would introduce lattice defects in the TiO2 thin film which will reduce photocurrent density and increase resistance. This work offers a systematic evaluation of the ETL in terms of morphological and photoelectrochemical properties, which can be applied when selecting suitable material for ETL in perovskite solar devices.