Features of a ZnxCd1 – xS Buffer Layer for Use in Thin-Film Solar Cells in the Context of a Literature Review

Abstract

The paper presents a literature review of the latest achievements in the creation of highly efficient thin-film solar cells (SCs) based on multicomponent polycrystalline materials: semiconductors of the AIIBVI groups of the periodic table, cadmium telluride (CdTe) and a three-component compound AIBIIICVI copper–indium–gallium and selenium (Cu (In, Ga)Se2). The main criteria for the selection of the buffer layer material for thin-film SCs based on CdTe and Cu (In, Ga)Se2 are analyzed. The values of the main output parameters of the load current–voltage characteristic (short-circuit current, open-circuit voltage, fill factor of a light current–voltage characteristic, efficiency) of high-performance SCs based on CdTe and Cu(In, Ga)Se2, which have been achieved to date, are presented. The spectral photosensitivity of a SC in the short-wave region of the electromagnetic spectrum is determined by the band gap width and thickness of the p–n transition frontal–buffer layer. An increase in the photosensitivity in the short-wave spectrum part of electromagnetic radiation is achieved by an increase in the band gap of the buffer layer. In this case, it is necessary to take into account the important energy (energy of electron affinity) and crystallographic (crystal lattice parameter) parameters of the semiconductor material. As one of the promising materials for the buffer layer, semiconductor polycrystalline layers from the AIIBVI class, semiconductor chemical ternary compounds ZnxCd1 – xS, in which Eg varies from 2.4 eV (x = 0, CdS) to 3.6 eV (x = 1, ZnS) are proposed. An analysis of the compatibility of ZnxCd1 – xS layers with different x values, as a buffer layer for SCs based on CdTe and Cu(In, Ga)Se2, is carried out. Possible scenarios of variation in the main output parameters of SCs, such as short-circuit current and open-circuit voltage, are analyzed.