Cu(In,Ga)Se₂ (CIGS) is a promising candidate to replace crystalline silicon solar cells and dominate the photovoltaic market in the future. Alkali elements such as sodium (Na), potassium (K), rubidium (Rb), and Cesium (Cs) are commonly accepted as indispensable parts to boost cell efficiencies of CIGS thin-film solar cells. Therefore, a comprehensive understanding of alkali effects on the electronic and chemical properties of the CIGS layer as well as the underlying mechanisms is of paramount importance for achieving high-performance solar cells. This paper reviews the development process and incorporation pathways of alkalis and then overviews the roles of different alkali elements and their effects on CIGS cells in detail. Furthermore, the unsolved problems and future development prospects are also proposed. Overall, the understanding and development of widely adopted alkali-fluoride post-deposition treatments (PDTs) are still underway, and together with newly updated research, it will likely enable the CIGS technology to make the conversion efficiency closer to its theoretical limit.

Cu(In,Ga)Se ₂（CIGS）是未来替代晶体硅太阳能电池并主导光伏市场的有希望的候选者。钠 (Na)、钾 (K)、铷 (Rb) 和铯 (Cs) 等碱元素被普遍认为是提高 CIGS 薄膜太阳能电池效率不可或缺的部分。因此，全面了解碱对 CIGS 层的电子和化学性质的影响及其潜在机制对于实现高性能太阳能电池至关重要。本文回顾了碱的发展过程和掺入途径，然后详细概述了不同碱元素的作用及其对 CIGS 细胞的影响。此外，还提出了未解决的问题和未来的发展前景。全面的，