Department of Materials Science and Engineering and ‡California NanoSystems Institute, University of California , Los Angeles, California 90095, United States.
Nano Lett. 2014 Jul 9;14(7):4158-63. doi: 10.1021/nl501838y. Epub 2014 Jun 30.
To improve the performance of the polycrystalline thin film devices, it requires a delicate control of its grain structures. As one of the most promising candidates among current thin film photovoltaic techniques, the organic/inorganic hybrid perovskites generally inherit polycrystalline nature and exhibit compositional/structural dependence in regard to their optoelectronic properties. Here, we demonstrate a controllable passivation technique for perovskite films, which enables their compositional change, and allows substantial enhancement in corresponding device performance. By releasing the organic species during annealing, PbI2 phase is presented in perovskite grain boundaries and at the relevant interfaces. The consequent passivation effects and underlying mechanisms are investigated with complementary characterizations, including scanning electron microscopy (SEM), X-ray diffraction (XRD), time-resolved photoluminescence decay (TRPL), scanning Kelvin probe microscopy (SKPM), and ultraviolet photoemission spectroscopy (UPS). This controllable self-induced passivation technique represents an important step to understand the polycrystalline nature of hybrid perovskite thin films and contributes to the development of perovskite solar cells judiciously.
为了提高多晶薄膜器件的性能，需要精细控制其晶粒结构。在当前的薄膜光伏技术中，有机/无机杂化钙钛矿是最有前途的候选材料之一，通常具有多晶性质，并在光电性质方面表现出组成/结构依赖性。在这里，我们展示了一种用于钙钛矿薄膜的可控钝化技术，该技术可实现其组成变化，并显著提高相应器件的性能。通过在退火过程中释放有机物质，PbI2 相出现在钙钛矿晶粒边界和相关界面处。通过互补的特性研究，包括扫描电子显微镜 (SEM)、X 射线衍射 (XRD)、时间分辨光致发光衰减 (TRPL)、扫描开尔文探针显微镜 (SKPM) 和紫外光电子能谱 (UPS)，研究了相应的钝化效应和潜在机制。这种可控的自诱导钝化技术代表了理解杂化钙钛矿薄膜多晶性质的重要一步，有助于合理开发钙钛矿太阳能电池。
