Aqueous precursors provide an alluring approach for low-cost and environmentally friendly production of earth-abundant Cu₂ZnSn(S, Se)₄ (CZTSSe) solar cells. The key is to find an appropriate molecular agent to prepare a stable solution and optimize the coordination structure to facilitate the subsequent crystallization process. Herein, we introduce thioglycolic acid (TGA), which possesses strong coordination (SH) and hydrophilic (COOH) groups, as the agent and use deprotonation to regulate the coordination competition within the aqueous solution. Ultimately, metal cations are adequately coordinated with thiolate anions, and carboxylate anions are released to become hydrated to form an ultrastable aqueous solution. These factors have contributed to achieving CZTSSe solar cells with an efficiency as high as 12.3% (a certified efficiency of 12.0%) and providing an extremely wide time window for precursor storage and usage. This work represents significant progress in the non-toxic solution fabrication of CZTSSe solar cells and holds great potential for the development of CZTSSe and other metal sulfide solar cells.

水性前驱体为低成本和环境友好地生产地球上丰富的 Cu ₂ ZnSn(S, Se) _{4提供了一种诱人的方法}(CZTSSe) 太阳能电池。关键是要找到合适的分子试剂来制备稳定的溶液并优化配位结构以促进后续的结晶过程。在此，我们引入具有强配位 (SH) 和亲水 (COOH) 基团的巯基乙酸 (TGA) 作为试剂，并使用去质子化作用来调节水溶液中的配位竞争。最终，金属阳离子与硫醇根阴离子充分配位，羧酸根阴离子被释放出来水合形成超稳定水溶液。这些因素有助于实现效率高达 12.3%（认证效率为 12.0%）的 CZTSSe 太阳能电池，并为前体存储和使用提供了极宽的时间窗口。