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Abstract In this paper, titanium dioxide (TiO 2) thin films, deposited on single crystal Si (111) substrates under different temperature conditions by Atomic Layer Deposition (ALD), have been systematically studied by X-ray diffraction, photoluminescence spectroscopy and spectroscopic ellipsometry methods. X-ray diffraction analysis showed that the prepared films have a polycrystalline brookite phase over a growth temperature range of (150–300 °C). Increasing the growth temperature resulted in systematic increase of texturing the polycrystalline grains along the (200) direction, with the film at 300 °C having the highest textur along the (200) direction. This was accompanied by improved photoluminescence of the TiO 2 films with the increasing the growth temperature. The improved crystallinity at higher temperatures was also reflected by higher refractive indices, which were deduced from spectroscopic ellipsometry measurements carried out on the grown films. Highlights • TiO 2 thin films with brookite phase successfully deposited on Si(111) using ALD. • Correlated Structural and optical properties perceived and studied. • Reduction of refractive index observed for films with ultra-small thicknesses. [ABSTRACT FROM AUTHOR]

The crystallization techniques of organic-inorganic hybrid perovskites (OIHP) are considered an effective method for light collector or light emitting applications. In this article, the optical band gap, electron-hole behavior, and energy band alignment are all key optoelectronic properties of crystalline perovskite structures studied in this study. For this reason, a perovskite solution was prepared in a single step and tetrahydrofuran (THF) was used as a solvent to dissolve both perovskite precursors. Rapid crystallization of perovskite in solution was observed, preventing the formation of homogenous perovskite thin films. Subsequently, the effect of THF solvent on the direct crystallization of MAPbI 3 perovskite without thermal annealing was investigated. Thermal annealing is considered necessary for perovskite crystal formation as it gives the molecules enough thermal energy to self-organize and form a well-ordered crystalline layer. The procedures that create perovskite crystals without thermal annealing give a novel method for room temperature film preparation (RT) and pave the way for the manufacture of low-cost, stable perovskite solar cells (PSCs). UV–vis absorption/reflectance, photoluminescence, XRD, and SEM were used to explore the effects of this approach on the optical and structural properties of MAPbI 3 perovskite thin films. • Crystallizing Growth of MAPbI 3 Perovskite Nanorod was demonstrated. • Perovskite precursor solution in THF is dried to form perovskite powder. • Fabrication of perovskite films without annealing. • Perovskite films were tested under ns laser. • The strong light emission allows the observation of ASE. [ABSTRACT FROM AUTHOR]