Gallet Thibaut, Poeira Ricardo G, Lanzoni Evandro M, Abzieher Tobias, Paetzold Ulrich W, Redinger Alex
Department of Physics and Materials Science, University of Luxembourg, Luxembourg City L-1511, Luxembourg.
Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.
ACS Appl Mater Interfaces. 2021 Jan 20;13(2):2642-2653. doi: 10.1021/acsami.0c19038. Epub 2021 Jan 6.
Hybrid organic-inorganic perovskites are highly promising candidates for the upcoming generation of single- and multijunction solar cells. Despite their extraordinarily good semiconducting properties, there is a need to increase the intrinsic material stability against heat, moisture, and light exposure. Understanding how variations in synthesis affect the bulk and surface stability is therefore of paramount importance to achieve a rapid commercialization on large scales. In this work, we show for the case of methylammonium lead iodide that a thorough control of the methylammonium iodide (MAI) partial pressure during co-evaporation is essential to limit photostriction and reach phase purity, which dictate the absorber stability. Kelvin probe force microscopy measurements in ultrahigh vacuum corroborate that off-stoichiometric absorbers prepared with an excess of MAI partial pressure exhibit traces of low-dimensional (two-dimensional, 2D) perovskites and stacking faults that have adverse effects on the intrinsic material stability. Under optimized growth conditions, time-resolved photoluminescence and work functions mapping corroborate that the perovskite films are less prone to heat and light degradation.
有机-无机杂化钙钛矿是新一代单结和多结太阳能电池极具潜力的候选材料。尽管它们具有极其优异的半导体性能，但仍需要提高材料对热、湿气和光照的本征稳定性。因此，了解合成过程中的变化如何影响体相和表面稳定性对于实现大规模快速商业化至关重要。在这项工作中，我们以甲基碘化铅为例表明，在共蒸发过程中彻底控制甲基碘化铵（MAI）的分压对于限制光致伸缩并达到相纯度至关重要，而相纯度决定了吸收体的稳定性。在超高真空下进行的开尔文探针力显微镜测量证实，用过量的MAI分压制备的非化学计量吸收体表现出低维（二维，2D）钙钛矿和堆垛层错的痕迹，这些对材料的本征稳定性有不利影响。在优化的生长条件下，时间分辨光致发光和功函数映射证实钙钛矿薄膜不易受热和光降解的影响。
