Ba2SiSe4: A promising candidate with visual light transparence and p-type electrical conductivity

Abstract

Commercially available transparent conducting materials (TCMs) concentrate on n-type, while the high-performance p-type TCMs are rare, which would impede the development of optoelectronics. Previous studies show Ba2SiSe4 possesses wide band-gap, smaller hole effective mass and high transmittance in visible light region [Chem. Mater. 30, 6794-6800 (2018)]. These characters imply that Ba2SiSe4 is a potential p-type TCM. However, the researches about its electrical conductivity are still lacking. In this work, the p-type defects are screened based on HSE hybrid functional calculations. We find the Cs substituting Ba (CsBa) is ideal p-type defects with the transition energy ε(0/-) 0.081 eV above the valance band maximum. Under the thermodynamic equilibrium fabrication scheme, the Cs2Se is the ideal dopant source for Cs dopants, and Se-rich, Ba (Si)-poor conditions are necessary to fabricate the CsBa defects. When the doped samples are quenched from the preparation temperature to room temperature, the hole density can reach 4.04×1017 cm-3, and the p-type electrical conductivity is 32.3 S/m. When the non-equilibrium fabrication scheme is considered, as the hole density reach 1020 cm-3 the corresponding p-type electrical conductivity can exceed 104 S/m. These results indicate that Ba2SiSe4 is a promising p-type TCM, which is valuable to develop the high-performance transparent electronic devices.