Structural and optical properties of highly crystallized and oriented Cs3Cu2I5 films prepared via aerosol-assisted chemical vapor deposition

Developing new technology is rather important of providing choice for scaling up production of perovskite film. An aerosol-assisted CVD (AACVD) system is constructed for fabricating lead-free Cs₃Cu₂I₅ perovskite films in this study. The 2D CFD simulation calculating the flow velocity distribution in the reaction chamber was conducted to determine the optimal growth position. The structural and optical property of the Cs₃Cu₂I₅ films grown on quartz, mica, ITO and FTO are systemically studied. The results reveals that well-crystallized Cs₃Cu₂I₅ film with orientation along (303) is grown on quartz substrate. The film prepared by AACVD process is composed of compact and uniform crystal grain of approximately 3.61 μm. Additionally, the Cs₃Cu₂I₅ film exhibits the gap energy of 3.78 eV, the fluorescence lifetime of 1.051 μs and the large Stokes shift of 145 nm. The film prepared on quartz and mica are mostly grown along (303) plane while prefer (400) plane when grow on ITO and FTO. Furthermore, the degree of preferred orientation of the Cs₃Cu₂I₅ films grown on quartz, mica, ITO and FTO are 1.734, 1.507, 1.444 and 1.295, respectively. The textured grown characteristic contributes to the self-trapped exciton (STE) transition process. Moreover, it proves that the degree of the film crystal structure preferred orientation is highly relevant with the crystal grain size and the photo-luminescence property. This study demonstrates that the AACVD method offers good strategy for preparing high-quality perovskite films.