Magneto-Optical Functionality and Energy Transfer in Metal-Halide Perovskite Nanocrystals Doped with Transition Metals

掺杂过渡金属的金属卤化物钙钛矿纳米晶体的磁光功能和能量传输

• 批准号: 410410899
• 负责人: Professor Dr. Gerd Bacher
• 金额: --
• 依托单位: Lehrstuhl Werkstoffe der Elektrotechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/410410899?language=en
• 关键词: Magneto; Optical; Functionality; Energy; Transfer

The overall goal of this project is to investigate the magneto-optical functionality and the energy transfer of perovskite nanocrystals doped with transition metals (TM, mainly Mn). The specific crystal structure of lead halide perovskites (APbX3, A = Cs, MA, FA; X = Cl, Br, I) is expected to allow for incorporation of TM2+ cations on six-fold coordinated lattice sites (replacing Pb2+) – in contrast to the more 'traditional' case of TM doping of II-VI chalocogenides, where the dopants are usually incorporated on four-fold coordinated sites. The uniqueness of these materials relies in addition on the different bandstructure (conduction band formed by p-states, valence band by s-states) and the more ionic bonds as compared to II-VI nanocrystals. Moreover, crystal phase transitions from the cubic to the tetragonal and finally the orthorhombic phase occur when lowering the temperature. In spite of several reports on Mn2+ doped APbX3 nanocrystals in literature there is no proof of any giant magneto-optical functionality caused by sp-d exchange interaction up to now. We intend to use magnetic circular dichroism measurements and magneto-photoluminescence experiments over a wide range of temperatures to investigate whether giant sp-d exchange effects are present in this novel material class, where the hybridization of the orbitals might significantly differ from II-VI nanocrystals due to the differently coordinated sites of the dopants and the more ionic bonds. In addition lead halide perovskites undergo a specific crystal phase transition when reducing the temperature leading to a discontinuous change of the emission energy. It is planned to investigate how this crystal phase transition affects the energy transfer from band states to luminescent dopants (and back), and whether this effect can be used for realizing dual emitters with two distinct critical temperatures by carefully adjusting the bandgap, e.g. by the Br/I ratio or the nanocrystal size, with respect to the internal 4T1 – 6A1 transition of the Mn2+ dopant.

本项目的总体目标是研究掺杂过渡金属（TM，主要是Mn）的钙钛矿纳米晶体的磁光功能和能量转移。卤化铅钙钛矿的特殊晶体结构（APbX3, A = Cs， MA， FA; X = Cl, Br， I）有望允许在六层配位点位上掺入TM2+阳离子（取代Pb2+） -与更“传统”的II-VI代硫属化合物的TM掺杂情况相反，掺杂剂通常在四层配位点位上掺入。与II-VI纳米晶体相比，这些材料的独特性还依赖于不同的带结构（由p态形成的导带，由s态形成的价带）和更多的离子键。当温度降低时，晶体由立方相转变为四方相，最后转变为正交相。尽管文献中有一些关于掺杂Mn2+的APbX3纳米晶体的报道，但到目前为止还没有证据表明sp-d交换相互作用引起了任何巨磁光功能。我们打算在广泛的温度范围内使用磁圆二色性测量和磁光致发光实验来研究这种新型材料类别中是否存在巨大的sp-d交换效应，其中由于掺杂剂的不同配位和更多离子键，轨道的杂化可能与II-VI纳米晶体显著不同。此外，卤化铅钙钛矿在降低温度时发生特定的晶体相变，导致发射能量的不连续变化。计划研究这种晶体相变如何影响从带态到发光掺杂的能量转移（以及返回），以及通过仔细调整带隙，例如通过Br/I比或纳米晶体尺寸，是否可以利用这种效应实现具有两种不同临界温度的双发射体，相对于Mn2+掺杂的内部4T1 - 6A1转变。