The Photovoltaic Cell Based on CIGS: Principles and Technologies

Abstract

Semiconductors used in the manufacture of solar cells are the subject of extensive research. Currently, silicon is the most commonly used material for photovoltaic cells, representing more than 80% of the global production. However, due to its very energy-intensive and costly production method, other materials appear to be preferable over silicon, including the chalcopyrite-structured semiconductors of the CIS-based family (Cu(In, Ga, Al) (Se, S)2). Indeed, these compounds have bandwidths between 1 eV (CuInSe2) and 3 eV (CuAlS2), allowing them to absorb most solar radiation. Moreover, these materials are currently the ones that make it possible to achieve the highest photovoltaic conversion efficiencies from thin-film devices, particularly Cu(In, Ga)Se2, which is considered the most efficient among all drifts based on CIS. In this review, we focus on the CIGS-based solar cells by exploring the different layers and showing the recent progress and challenges.

Environment-friendly copper-based chalcogenide thin film solar cells: status and perspectives

“…256 To avoid volume and interface recombination in the Cu Ch / n -buffer layer, it is also essential to remove the electronic junction of the physical junction rich in detrimental defects. 258 In this case, a surface inversion could be conducted by generating a Ga gradient on the surface of the absorber with an n -buffer layer. 258…”

“…258 In this case, a surface inversion could be conducted by generating a Ga gradient on the surface of the absorber with an n -buffer layer. 258…”

“…For instance, CdS is a common n -buffer layer used in CIGS-based solar cells and is found to reduce the detrimental defects at the interfaces between CIGS and CdS layers to minimize the recombination of carriers, and the chemical bath deposition method to deposit the CdS layer on top of CIGS layer become one of the best strategies. 258 When we use a more environmentally friendly n -buffer layer of ZnO instead of CdS, a special strategy to improve the interface between ZnO and Cu Ch layer also should be taken into account to obtain high PCE. For instance, in the CIGS/ZnO interface, a negative conduction band offset of −0.2 eV was previously obtained.…”

“…Thus, by avoiding a negative discontinuity between the ZnO and CIGS layers, the buffer layer allows the optimal alignment of the conduction bands. 258 In addition, the interfacial condition between Cu Ch and the bottom electrode is also important. Ga grading in the Cu Ch layer, as we explained previously, is one of the strategies to improve the interface between the Cu Ch layer and the bottom electrode.…”

“…256 To avoid volume and interface recombination in the CuCh/n-buffer layer, it is also essential to remove the electronic junction of the physical junction rich in detrimental defects. 258 This journal is © The Royal Society of Chemistry 2023…”