First-principles study of e interface interaction and photoelectric properties of the solar cell heterojunction CdS/CdMnTe

Abstract

CdS/CdMnTe heterojunction is the core of photoelectric conversion of CdMnTe film solar cells, whose interface properties have an important influence on the cell efficiency. In this study, the first-principles calculation method based on density functional theory is used to build the surface model for each of the CdS (002) and the CdMnTe (111) and the model of CdS/CdMnTe heterojunction with Mn atoms occupying different positions, and to analyze their electronic properties and optical properties. The results show that the lattice mismatch of the CdS/CdMnTe heterojunction is about 3.5%, the atomic positions and bond lengths of the interface change slightly after relaxation. The density of states shows that there is no interface state near the Fermi level in CdS/CdMnTe interface. Besides, the atoms at CdS/CdMnTe interface are hybridized, which can enhance the interface bonding. The differential charge density analyses indicate that the charge transfer mainly occurs at the interface, and electrons transfer from CdMnTe to CdS. The optical analysis shows that CdS/CdMnTe heterojunction mainly absorbs ultraviolet light, and the absorption coefficient can reach 10<sup>5</sup> cm<sup>–1</sup>. However, the optical properties of heterojunctions with different Mn atom positions are slightly different. In a range of 200–250 nm, the absorption coefficient of the heterojunction with Mn atom in the middle layer is larger, but in a range of 250–900 nm, the absorption peak of the heterojunction with Mn atom in the interface layer is higher. The results in this paper can provide some references for improving the photoelectric conversion efficiency of stacked solar cells through the reasonable construction of the heterojunction model and the analysis of the interface photoelectric performance, which is beneficial to the experimental research of multi-band gap heterojunction.

Study of the photovoltaic properties of Cs and Cl co-doped FAPbI3 based on first principles

“…The development of economy and technology cannot be supported by energy sources, which are mainly nonrenewable energy sources, such as oil, coal and natural gas. As increased energy are used, there are few reserves of energy left on the Earth, and the environmental problems caused using non-renewable energy sources have also caused concern in many countries, so they hope to vigorously develop renewable and clean energy sources such as solar energy [1][2][3][4][5]. The conversion efficiency of solar cells depends on the photoelectric conversion of their photo absorption layer, and the special properties of perovskite materials, such as direct and tunable band gap, high lattice defect tolerance, high usage efficiency of photogenerated carriers and high light absorption coefficient, are particularly suitable for use as a photo absorption layer in solar cells [6,7].…”

Study of the photovoltaic properties of Cs and Cl co-doped FAPbI 3 based on first principles

“…The development of economy and science and technology cannot be supported by energy sources, which are mainly non-renewable energy sources, such as oil, coal and natural gas. As more and more energy is used, there are few reserves of energy left on the earth, and the environmental problems caused by the use of non-renewable energy sources have also caused concern in many countries, so they hope to vigorously develop renewable and clean energy sources such as solar energy [1][2][3][4][5] . The conversion e ciency of solar cells depends largely on the photoelectric conversion of their photoabsorption layer, and the special properties of chalcogenide materials, such as direct and tunable band gap, high lattice defect tolerance, high usage e ciency of photogenerated carriers and high light absorption coe cient, are particularly suitable for use as a photoabsorption layer in solar cells 6,7 .…”