Titanium-Doped BaZrS₃ Chalcogenide Perovskite for Photovoltaic Applications: Structural, Optical, and Electrical Properties

Chalcogenide perovskites, such as BaZrS₃, have emerged as promising alternatives to lead-based halide perovskites, addressing toxicity and instability concerns while maintaining strong near-band-edge absorption and high carrier mobility. In this study, titanium-doped BaZrS₃ (BaZr₁_-_<i>x</i>Ti_<i>x</i>S₃, <i>x</i> = 0-0.08) was synthesized via citric acid-based sol-gel method, followed by sulfurization at 1050 °C. Structural characterization confirmed the a single-phase distorted orthorhombic perovskite without phase separation, even at 8% Ti doping. Raman spectroscopy revealed no significant structural disorder induced by Ti substitution, while SEM/TEM analyses demonstrated a uniform morphology and pseudocubicnanoparticles (∼200 nm) in size. XPS validated the presence of Ba²⁺, Zr⁴⁺and S^2- in their expected oxidation states. UV-Vis spectroscopy showed a tunable bandgap reduction from 1.8 eV (pristine) to 1.2 eV (<i>x</i> = 0.08), aligning with the Shockley-Queisser limit. Hall effect measurements revealed enhanced carrier mobility (27.4 cm²/V·s at <i>x</i> = 0.08) and consistent n-type carrier concentrations (∼10¹⁶ cm^-3), indicating improved conductivity. The thermogravimetric analysis further confirmed exceptional thermal stability (<2% Mass loss up to 800 °C). These results underscore the efficacy of Ti doping in optimizing optoelectronic properties while preserving structural integrity and stability. Collectively, this work positions Ti-doped BaZrS₃ as a scalable, lead-free perovskite candidate for high-efficiency photovoltaic applications.