He Dongxu, Chen Peng, Steele Julian A, Wang Zhiliang, Xu Hongyi, Zhang Meng, Ding Shanshan, Zhang Chengxi, Lin Tongen, Kremer Felipe, Xu Hongzhe, Hao Mengmeng, Wang Lianzhou
Australian Institute for Bioengineering and Nanotechnology and School of Chemical Engineering, The University of Queensland, Brisbane, Queensland, Australia.
School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, Australia.
Nat Nanotechnol. 2025 Apr 16. doi: 10.1038/s41565-025-01905-4.
Tin halide perovskites (THPs) have emerged as promising lead-free candidates for eco-friendly perovskite solar cells, but their photovoltaic performance still lags behind that of lead-based counterparts due to poor thin-film quality. Constructing two-dimensional/three-dimensional (2D/3D) heterostructures can effectively regulate crystallization and suppress defect formation for developing high-quality THP thin films. However, the high aggregation barrier prevents large 2D perovskite colloids from forming stable clusters, making 2D THPs nucleate more slowly than their 3D analogues. Such distinct nucleation kinetics cause undesirable 2D/3D phase segregation that compromises both photovoltaic performance and device durability. Here we introduce small inorganic caesium cations to partially replace bulky organic cations in the electrical double layers of 2D THP colloids, reducing the colloid size to lower their aggregation barrier. The reduced electrostatic repulsion promotes the coagulation of 2D and 3D THP colloids in the precursor solution, synchronizing their nucleation kinetics for the growth of 2D/3D heterostructured THP thin films with a homogeneous microstructure and markedly reduced trap states. Consequently, the caesium-incorporated THP solar cells deliver an excellent power conversion efficiency of 17.13% (certified 16.65%) and exhibit stable operation under continuous one-sun illumination for over 1,500 h in nitrogen without encapsulation. This study offers new insights into the colloidal chemistry and crystallization engineering of mixed-dimensional heterostructures, paving the way for high-performance lead-free perovskite photovoltaics.
卤化锡钙钛矿（THPs）已成为环保型钙钛矿太阳能电池有前景的无铅候选材料，但由于薄膜质量差，其光伏性能仍落后于铅基同类材料。构建二维/三维（2D/3D）异质结构可以有效调节结晶并抑制缺陷形成，以制备高质量的THP薄膜。然而，高聚集势垒阻碍了大尺寸二维钙钛矿胶体形成稳定的聚集体，使得二维THPs的成核速度比其三维类似物更慢。这种明显不同的成核动力学导致不希望的二维/三维相分离，从而损害了光伏性能和器件耐久性。在此，我们引入小的无机铯阳离子，以部分取代二维THP胶体双电层中的大体积有机阳离子，减小胶体尺寸以降低其聚集势垒。降低的静电排斥促进了二维和三维THP胶体在前驱体溶液中的凝聚，使它们的成核动力学同步，以生长具有均匀微观结构和显著减少陷阱态的二维/三维异质结构THP薄膜。因此，掺入铯的THP太阳能电池具有17.13%的优异功率转换效率（认证值为16.65%），并且在氮气中无封装的情况下，在连续一个太阳光照下稳定运行超过1500小时。这项研究为混合维度异质结构的胶体化学和结晶工程提供了新的见解，为高性能无铅钙钛矿光伏技术铺平了道路。
