Zhang Xueyun, Huang Jialiang, Cong Jialin, Sun Kaiwen, Liu Fangyang, Hao Xiaojing
School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
Small. 2025 Jul;21(27):e2411241. doi: 10.1002/smll.202411241. Epub 2025 May 28.
Alkali metals (AMs) doping is commonly accepted as an indispensable strategy to enhance the efficiency of CuSnZn(S, Se) (CZTSSe) thin-film solar cells. However, while extensive research has been focused on light AMs, heavy AMs have lacked attention in studies. In this work, a novel solution-based approach is employed to achieve cesium doping in CZTSSe-based thin-film solar cells compared with conventional post-deposition methods. This strategy allows cesium to diffuse into the absorber from the rear side of the precursor film before selenization, enabling its participation in the crystallization process without affecting the phase structure of CZTSSe. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra demonstrate that cesium is detected in the middle and rear region of the absorber. Further studies reveal that cesium mainly accumulates at the grain boundaries of the absorber and effectively suppresses non-radiative recombination in the bulk of the absorber, leading to enlarged grain size and improved electrical properties of the CZTSSe device. This ultimately resulted in enhanced open-circuit voltage (V) and fill factor (FF), thus improving the photovoltaic performance.
碱金属（AM）掺杂是提高铜锡锌（硫，硒）（CZTSSe）薄膜太阳能电池效率的一种不可或缺的策略，这一点已被广泛认可。然而，尽管大量研究集中在轻碱金属上，但重碱金属在研究中却未受到关注。在这项工作中，与传统的沉积后方法相比，采用了一种新型的基于溶液的方法在基于CZTSSe的薄膜太阳能电池中实现铯掺杂。该策略使铯在硒化之前从前驱体薄膜的背面扩散到吸收层中，使其能够参与结晶过程而不影响CZTSSe的相结构。飞行时间二次离子质谱（TOF-SIMS）光谱表明，在吸收层的中部和后部区域检测到了铯。进一步的研究表明，铯主要聚集在吸收层的晶界处，并有效抑制了吸收层主体中的非辐射复合，导致晶粒尺寸增大，CZTSSe器件的电学性能得到改善。这最终导致开路电压（V）和填充因子（FF）提高，从而改善了光伏性能。
