The growth, structure and optics of CsI-PbI2 co-evaporated thin films

The structure and optical properties of thin films grown by the vacuum co-evaporation of CsI and PbI2 powders from two independent crucibles were studied. The typical thickness of the films grown was approximately 0.5 mum. X-Ray diffraction spectroscopy using different grazing angles (0.1 degrees -2 degrees) revealed formation of ternary phases, namely CsPbI3 and Cs4PbI6 ones in the thin film samples and gave an estimate of their volume percentage as well. The aggregate sizes were estimated by the Warren-Aberbach method and were found at approximately 20-40 nm. Furthermore, a direct observation of the thin film surface by atomic force microscopy was performed. The absorption and luminescence spectroscopies were employed to characterize the optical properties of these ternary nanoaggregate phases in 4.2-300 K temperature ranges. (C) 2000 Elsevier Science S.A. All rights reserved.