Ozone-mediated Controllable Hydrolysis for High Quality Amorphous NbO <sub/>x</sub> Electron Transport Layer in Efficient Perovskite Solar Cells

摘要： Amorphous NbOx electron transport layer (ETL) shows great potential for boosting the power conversion efficiency (PCE) of perovskite solar cells (PSCs) at low temperature (< 100 °C). To date, it is still a challenge to simultaneously control the hydrolysis of NbOx precursor solution and reduce the impurities of NbOx ETLs during low-temperature solution processing under ambient conditions. Herein, for the first time, we report ozone (O3) as a strong ligand to stabilize Nb salt solution under ambient conditions. The above procedure not only provides the formation of a highly repeatable amorphous NbOx film by suppressing the hydrolysis of the solution but also reduces the OH content in the film, which decreases the defect intensity and improves the conductivity of the NbOx ETL. Thus, the formation of highly repeatable NbOx ETL-based PSCs are obtained; moreover, these PSCs have high PCE of 19.54% and 16.42% on rigid and flexible substrate, respectively, much higher than the devices based on ETLs from a solution without an O3 treatment.