Ahmed Ghada H, Liu Yun, Bravić Ivona, Ng Xejay, Heckelmann Ina, Narayanan Pournima, Fernández Martin S, Monserrat Bartomeu, Congreve Daniel N, Feldmann Sascha
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Cavendish Laboratory, University of Cambridge, Cambridge CB30HE, U.K.
J Am Chem Soc. 2022 Aug 31;144(34):15862-15870. doi: 10.1021/jacs.2c07111. Epub 2022 Aug 17.
Metal-halide perovskite nanocrystals have demonstrated excellent optoelectronic properties for light-emitting applications. Isovalent doping with various metals (M) can be used to tailor and enhance their light emission. Although crucial to maximize performance, an understanding of the universal working mechanism for such doping is still missing. Here, we directly compare the optical properties of nanocrystals containing the most commonly employed dopants, fabricated under identical synthesis conditions. We show for the first time unambiguously, and supported by first-principles calculations and molecular orbital theory, that element-unspecific symmetry-breaking rather than element-specific electronic effects dominate these properties under device-relevant conditions. The impact of most dopants on the perovskite electronic structure is predominantly based on local lattice periodicity breaking and resulting charge carrier localization, leading to enhanced radiative recombination, while dopant-specific hybridization effects play a secondary role. Our results suggest specific guidelines for selecting a dopant to maximize the performance of perovskite emitters in the desired optoelectronic devices.
金属卤化物钙钛矿纳米晶体在发光应用中展现出了优异的光电性能。用各种金属（M）进行等价掺杂可用于调整和增强其发光。尽管对于最大化性能至关重要，但对于这种掺杂的通用工作机制仍缺乏了解。在此，我们直接比较了在相同合成条件下制备的含有最常用掺杂剂的纳米晶体的光学性质。我们首次明确表明，并得到第一性原理计算和分子轨道理论的支持，即在与器件相关的条件下，元素非特异性的对称性破缺而非元素特异性的电子效应主导了这些性质。大多数掺杂剂对钙钛矿电子结构的影响主要基于局部晶格周期性的破坏以及由此导致的电荷载流子局域化，从而增强了辐射复合，而掺杂剂特异性的杂化效应起次要作用。我们的结果为选择掺杂剂以最大化钙钛矿发光体在所需光电器件中的性能提供了具体指导方针。
