A Comprehensive Perspective on the Fabrication of CuGaSe₂/Si Tandem Solar Cells

Abstract

This review points out the current need for further research on tandem solar cells as the commercial single‐junction solar cell technologies report close to their maximum performance limit. First, the conceptual insight and the desired interconnection schemes for tandem solar cells are briefly presented. Then, a comprehensive discussion on the structural, optical, and electronic properties of CuGaSe2, evaluating its use as a top cell absorber material, is presented. Furthermore, the current status and the critical analysis of CuGaSe2 solar cells, which finds that the adapted conventional device architecture possesses severe limitations, are presented. Based on the drawbacks of the existing materials in use, new materials to fabricate CuGaSe2 solar cells are proposed. Also, tandem configurations with newly proposed CuGaSe2 solar cell architecture by choosing Si photovoltaics as bottom cells are devised. In the end, further challenges in the devised tandem configurations with a focus on their band alignments are elucidated.

Brief Outlook on Top Cell Absorber of Silicon‐Based Tandem Solar Cells

“…The data provided by Yamaguchi et al is updated for chalcogenides/Si in Figure 10 and CdMgTe/Si tandem SC is added by keeping in view the trend of CdZnTe. The current status and [191] Copyright 2021, Wiley-VCH. b) Calculated band edges for materials used in conventional CGSe SCs including buffer and window layer.…”

“…Both types are speculated in Figure along with energy distribution where CdS is taken as an example. [ 191 ] The conduction band offset (CBO) of CdS is cliff type as given in Figure 9a,b. Such a CBO has higher voltage loss due to an unfavorable band offset.…”

“…Figure9. a) Cliff-type band alignment in conventional CGSe SCs with CdS as a buffer layer, Reproduced with permission [191]. Copyright 2021, Wiley-VCH.…”

“…c) Spike-type band alignment for CGSe SC with desired buffer and window layer. Reproduced with permission [191]. Copyright 2021, Wiley-VCH.…”

“…d) Calculated band edges for proposed materials can be used in CGSe SCs including buffer and window layer. Reproduced with permission [191]. Copyright 2021, Wiley-VCH.…”