Thin Film of TiO2–ZnO Binary Mixed Nanoparticles as Electron Transport Layers in Low-Temperature Processed Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells have become one of the highly promising candidates for photovoltaic technologies because of their low processing cost, rapid-growing power conversion efficiency and easy preparation process. Electron transfer layer (ETL) plays an important role in exciton separation and charge transport for perovskite devices. A TiO 2 –ZnO binary mixed nanoparticle (NP) ETL, which can be prepared in low-temperature hydrothermal method, was proposed. By analyzing the XRD and SEM, the incorporation of mixed NPs thin film improved the interfacial stability of ZnO/perovskite and prevented the perovskite layer from being decomposed as compared to the pure ZnO NPs thin film. Furthermore, UV spectrum and EIS results show that TiO 2 –ZnO mixed NP ETL has high transmittance and maintains good electrical properties of pure ZnO NPs basically. Finally, the efficiency of perovskite device based on TiO 2 –ZnO mixed NP ETL was improved to 15%. Our research provides a simple way for the application of ZnO in PCSs.