On Tailoring Structural and Optoelectronic Properties of TiO2 Thin Films Synthesized via 'Room' Temperature High Power Impulse Magnetron Sputtering (HiPIMS)

Titanium dioxide (TiO2) is a key material in optoelectronic and energy conversion technologies, including solar cells and photocatalysis. However, integrating TiO2 into flexible or temperature-sensitive devices requires deposition techniques that avoid high-temperature processing while maintaining control over both phase composition and crystallinity. In this work, we demonstrate the synthesis of nanocrystalline TiO2 thin films using High Power Impulse Magnetron Sputtering (HiPIMS) at nearroom temperature. By systematically varying total pressure and oxygen flow, we achieve tunable anatase to rutile phase ratios and control over crystalline quality, as evidenced by Raman and photoluminescence trends. The observed optical trends in both refractive index and emission are directly linked to the underlying structural evolution, with compositional analysis verifying stoichiometric consistency across all deposition conditions. Our findings establish HiPIMS as a powerful low temperature method for tailoring TiO2 thin films and enabling their application in flexible photovoltaics, photoelectrochemical water splitting, and other energy-related systems.