Structural, electronic, and optical properties of S and Se substituted PbTiO ₃ : A first‐principles’ investigation

Abstract In the quest for renewable energy solutions, ferroelectric perovskite materials have garnered attention due to their superior photovoltaic properties. This study investigates the substitution of sulfur (S) and selenium (Se) for oxygen (O) in lead titanate (PbTiO 3 ) to improve its photovoltaic performance. Utilizing standard and hybrid density functional theory method, the geometrical, electronic, spontaneous polarization, and optical properties of S‐ and Se‐substituted PbTiO 3 are analyzed. It is shown that both S and Se substitutions reduce the band gap of PbTiO 3 and Se substitution shows a more pronounced effect. The band gaps of 1.58 eV for PbTiS 3 and 1.14 eV for PbTiSe 3 are found to be significantly smaller than that of intrinsic PbTiO 3 , which are close to the value of 1.3 eV for ideal photovoltaic materials. Furthermore, S and Se substitutions enhance the spontaneous polarization and UV light absorption capabilities of PbTiO 3 , with Se‐substituted PbTiO 3 exhibiting higher polarization intensities and superior UV absorption. Especially, there is a shift in optical absorption of Se‐substituted PbTiO 3 toward the visible light spectrum and significant anisotropy in the UV range. The presented results suggest that Se‐substituted PbTiO 3 holds promise as a candidate for efficient photovoltaic applications.