CAS Institute of Physics Sets World Record for CuZnSnSSe Photovoltaic Module Efficiency at 13.0%

en.Wedoany.com Reported - The research team led by Professor Meng Qingbo at the Institute of Physics, Chinese Academy of Sciences, has fabricated a large-area Cu₂ZnSn(S,Se)₄ thin-film photovoltaic module with a photoelectric conversion efficiency of 13.0%, setting a new world record for this type of module. The related results were published online in Nature Materials.

Cu₂ZnSn(S,Se)₄ is a new type of thin-film photovoltaic material composed of earth-abundant, low-cost, and environmentally friendly elements such as copper, zinc, and tin, and is considered an important direction for next-generation sustainable solar cells. In recent years, Meng's team has set the world record for the efficiency of this type of cell ten times. However, once the device size is scaled up, the uniformity of the thin film deteriorates sharply, and the efficiency correspondingly decreases, which has become a key challenge for the practical application of this technology.

According to Meng Qingbo, the problem lies in the solution process. In traditional methods, metal ions and organic molecules form a complex cross-linked network, leading to non-uniform solvent evaporation, elemental distribution, and crystallization processes—much like having too many lumps in dough, resulting in a rolled-out "dough sheet" of uneven thickness. To address this, the team started at the molecular scale and introduced formamide as a coordination-regulating agent to precisely control the coordination structure between metal ions and organic molecules, thereby breaking this cross-linked network.

Based on this molecular coordination regulation strategy, the team developed a solution-coating process suitable for large-area continuous production, producing a highly uniform Cu₂ZnSn(S,Se)₄ thin film on a 10 cm² substrate. A 1 cm² small-area cell made from this film achieved a certified efficiency of 14.2%; after laser scribing to form a module with six sub-cells connected in series and a total area of 10.5 cm², the certified efficiency still reached 13.0%.

Meng Qingbo stated that this research demonstrates that Cu₂ZnSn(S,Se)₄ thin-film technology can not only perform well at small laboratory scales but also holds potential for scale-up production and industrialization, providing a new approach for the large-scale manufacturing of low-cost, green thin-film photovoltaic modules.