Kesterite Cu₂ZnSn(S, Se)₄ (CZTSSe) thin-film solar cells are emerging photovoltaic technology, having distinctive advantages including abundant elemental reserves, environmental friendliness, and high material stability. The photoelectric conversion efficiency of these cells has reached the commercial threshold of 15%, positioning them as a promising candidate for the future photovoltaic market. Exploring all-solution processes, especially for the transparent window layers, will help further reduce the manufacturing cost of the cell and thus promote its competitiveness in the commercialization process.

However, the interface contact issue, surface defects, and energy level mismatches have significantly limited the optoelectronic performance of solution-processed transparent window layers. Recently, MENG Qingbo’s group from Institute of Physics, Chinese Academy of Sciences has systematically investigated and addressed these challenges by employing molecular engineering to regulate the multiple interfaces of ZnO nanoparticles (ZnO-nps)/silver nanowires (AgNWs) window layers in kesterite solar cells. The interface molecular engineering enhances the conformal deposition of ZnO-nps on rough CZTSSe/CdS substrates, passivates hydroxyl defects in ZnO-nps, and optimizes energy level alignment at the ZnO-nps/AgNWs interface. These advancements help to achieve a certified total area efficiency of 14.3%, marking a significant milestone for all-solution-processed kesterite solar cells.

Furthermore, the solution-processed window layer forms a robust and flexion-tolerant lateral conductive network, imparting excellent flexibility to the cells. These results demonstrate a valuable pathway for the more cost-effective and efficient manufacturing of high-performance kesterite solar cells and also contribute to enhancing the multi-scenario application potential of this thin-film photovoltaic technology.

This study entitled “Multi-interface engineering for all-solution-processed kesterite solar cells” was published on Joule.

The study was supported by the National Key R&D Program of China, National Natural Science Foundation of China, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and China National Postdoctoral Program for Innovative Talents.