Theoretical Dissection of Cation-Deficient Layered Ruddlesden-Popper Oxysulfide Perovskites with a High-Efficiency Carrier Transport Channel

Yisen Yao; Qiaoqiao Li; Yi-Min Ding; Luo Yan; Weiwu Chen; Alexander Govorov; Zhiming Wang; Liujiang Zhou

doi:10.1021/acs.jpclett.3c02255

Theoretical Dissection of Cation-Deficient Layered Ruddlesden-Popper Oxysulfide Perovskites with a High-Efficiency Carrier Transport Channel

J Phys Chem Lett. 2023 Oct 12;14(40):9075-9081. doi: 10.1021/acs.jpclett.3c02255. Epub 2023 Oct 3.

Authors

Yisen Yao¹, Qiaoqiao Li², Yi-Min Ding³, Luo Yan², Weiwu Chen³, Alexander Govorov^{1

4}, Zhiming Wang¹, Liujiang Zhou^{2

3}

Affiliations

¹ Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
² School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China.
³ Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, China.
⁴ Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, United States.

PMID: 37788153
DOI: 10.1021/acs.jpclett.3c02255

Abstract

The search for lead-free perovskite materials has triggered intensive interest. Here, we study the electronic structures and optical properties of cation-deficient Ruddlesden-Popper oxysulfide perovskites Ln₂Ti₂O₅S₂ (Ln = Sc, Y, or La), with a tunable band gap of 1.45-2.1 eV and a small exciton binding energy of ∼0.1 eV, among which Y₂Ti₂O₅S₂ has been synthesized experimentally. Sc₂Ti₂O₅S₂ possesses the largest light absorbance in the visible region. We further rationalize the light absorption via the transition dipole moment and suggest potential applications of Sc₂Ti₂O₅S₂ in solar cells and Y₂Ti₂O₅S₂ and La₂Ti₂O₅S₂ in water splitting. In addition, this family exhibits small effective masses within the x-y plane and large ones along the z direction. Most importantly, electron gas-like carrier behaviors are observed within the Ti-O bond region, offering a diffusion channel for electron transport. These findings greatly advance our understanding of lead-free perovskites and offer a novel material platform for future optoelectronic devices.