Eliminating oxygen vacancies in SnO₂ films via aerosol-assisted chemical vapour deposition for perovskite solar cells and photoelectrochemical cells

Thin film deposition technologies are rapidly advancing especially in the field of solar energy storage and solar cells. Herein, spin coating and aerosol-assisted chemical vapour deposition (AACVD) are chosen to represent solution-based and vapour-based deposition routes, respectively. SnO₂ films processed at low temperature via the mentioned methods are applied in photoelectrochemical (PEC) cell as active photoanode and perovskite solar cell (PSC) as electron transport layer. This study discovers that spin coated SnO₂ film which consists of greater amount of oxygen vacancy is beneficial for PEC cell but is detrimental towards the stability and hysteresis of PSC device. The improved PEC performance is majorly attributed to the enhanced light absorption of SnO₂ caused by the reduction of its band gap energy. Meanwhile, AACVD method successfully eliminates oxygen vacancy in SnO₂ crystal lattice. Although PEC cell shows very poor performance upon using AACVD-fabricated SnO₂, the employment of this layer greatly enhances the overall performance of PSC. The absence of oxygen vacancy allows efficient charge transfer at SnO₂/perovskite interface and renders SnO₂ less hydrophobic which prevents moisture-induced degradation of perovskite layer. Our findings provide valuable information to understanding the film formation mechanism of different fabrication technologies and their suitability for particular optoelectronic application.