Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China.
Nanoscale. 2019 Mar 28;11(13):6182-6191. doi: 10.1039/c9nr00143c.
Inorganic lead halide perovskite CsPbX3 (X = Cl, Br, or I) nanocrystals are promising candidate materials for light-emitting devices and optoelectronics. Mn-Doped CsPbX3 is of particular interest, as the Mn-doping introduces an additional emission band, making this material a promising white-light emitter. In this study, Mn-doped CsPb(Br/Cl)3 nanocrystals are prepared at room-temperature and ambient pressure. The chemical environment of Mn, and the luminescence of these nanocrystals are analyzed in detail using X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL). Although the introduction of Mn does not alter the long-range order of the CsPbX3 crystal, it leads to a local lattice contraction with the bond length of Mn-X much shorter than Pb-X. We also find excitation energy-dependence in both the intensity and wavelength of the perovskite excitonic emission band, while only in intensity of the Mn emission band. Detailed fitting of the XEOL reveals that the perovskite emission band is dual-channel, and it is the excitation energy-dependent intensity variation of these two channels that drives the observed red-shift of the combined emission band. Our findings also confirm that the Mn emission band is driven by exciton-Mn energy transfer and clarify the Mn chemical environment and the luminescence mechanism in Mn-doped CsPb(Br/Cl)3 nanocrystals.
无机卤化铅钙钛矿 CsPbX3（X=Cl、Br 或 I）纳米晶体是发光器件和光电器件的有前途的候选材料。Mn 掺杂的 CsPbX3 特别有趣，因为 Mn 掺杂引入了额外的发射带，使这种材料成为一种有前途的白光发射器。在这项研究中，在室温常压下制备了 Mn 掺杂的 CsPb(Br/Cl)3 纳米晶体。使用 X 射线衍射（XRD）、扩展 X 射线吸收精细结构（EXAFS）、X 射线吸收近边缘结构（XANES）和 X 射线激发光致发光（XEOL）详细分析了 Mn 的化学环境和这些纳米晶体的发光。尽管 Mn 的引入不会改变 CsPbX3 晶体的长程有序，但它会导致局部晶格收缩，Mn-X 的键长明显短于 Pb-X。我们还发现，在钙钛矿激子发射带的强度和波长上都存在激发能依赖性，而只有 Mn 发射带的强度存在依赖性。XEOL 的详细拟合表明，钙钛矿发射带是双通道的，正是这两个通道的激发能依赖性强度变化导致了观察到的组合发射带的红移。我们的研究结果还证实，Mn 发射带是由激子-Mn 能量转移驱动的，并阐明了 Mn 掺杂 CsPb(Br/Cl)3 纳米晶体中的 Mn 化学环境和发光机制。
