Electronic, Structural, and Optical Properties of Mono-Doped and Co-Doped (210) TiO₂ Brookite Surfaces for Application in Dye-Sensitized Solar Cells—A First Principles Study

• Main Authors: Ratshilumela S. Dima, Lutendo Phuthu, Nnditshedzeni E. Maluta, Joseph K. Kirui, Rapela R. Maphanga
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Materials
• Subjects: on-metal; brookite TiO₂; doping mechanism; optical properties; density functional theory
• Online Access: https://www.mdpi.com/1996-1944/14/14/3918

Titanium dioxide (TiO₂) polymorphs have recently gained a lot of attention in dye-sensitized solar cells (DSSCs). The brookite polymorph, among other TiO₂ polymorphs, is now becoming the focus of research in DSSC applications, despite the difficulties in obtaining it as a pure phase experimentally. The current theoretical study used different nonmetals (C, S and N) and (C-S, C-N and S-N) as dopants and co-dopants, respectively, to investigate the effects of mono-doping and co-doping on the electronic, structural, and optical structure properties of (210) TiO₂ brookite surfaces, which is the most exposed surface of brookite. The results show that due to the narrowing of the band gap and the presence of impurity levels in the band gap, all mono-doped and co-doped TiO₂ brookite (210) surfaces exhibit some redshift. In particular, the C-doped, and C-N co-doped TiO₂ brookite (210) surfaces exhibit better absorption in the visible region of the electromagnetic spectrum in comparison to the pure, S-doped, N-doped, C-S co-doped and N-S co-doped TiO₂ brookite (210) surfaces.