Ba2SiSe4: a promising candidate with visual light transparency and p-type electrical conductivity

Abstract

Commercially available transparent conducting materials (TCMs) are typically n-type, and high-performance p-type TCMs are rare, which would impede the development of optoelectronics. Previous studies have shown that Ba₂SiSe₄ possesses a wide band-gap, low hole effective mass and high transmittance in the visible light region [R. Kormath Madam Raghupathy et al., Chem. Mater., 2018, 30, 6794–6800]. These characteristics imply that Ba₂SiSe₄ is a potential p-type TCM. However, research studies on its electrical conductivity are limited. In this work, p-type defects are screened based on HSE hybrid functional calculations. We find that Cs substituting Ba(Cs_Ba) is an ideal p-type defect with a transition energy (ε(0/−)) of 0.081 eV above the valence band maximum. Under the thermodynamic equilibrium fabrication scheme, Cs₂Se is the ideal dopant source for Cs dopants, and Se-rich, Ba (Si)-poor conditions are necessary to fabricate Cs_Ba defects. When doped samples are quenched from the preparation temperature to room temperature, their hole density reaches 4.04 × 10¹⁷ cm⁻³, and their p-type electrical conductivity reaches 32.3 S m⁻¹. When a non-equilibrium fabrication scheme is considered, as the hole density reaches 10²⁰ cm⁻³, the corresponding p-type electrical conductivity exceeds 10⁴ S m⁻¹. These results indicate that Ba₂SiSe₄ is a promising p-type TCM, which is valuable in developing high-performance transparent electronic devices.