Doping-Enhanced Short-Range Order of Perovskite Nanocrystals for Near-Unity Violet Luminescence Quantum Yield
Doping-Enhanced Short-Range Order of Perovskite Nanocrystals for Near-Unity Violet Luminescence Quantum Yield
复制标题
钙钛矿纳米晶体的掺杂增强短程有序以获得近乎一致的紫光发光量子产率
DOI：
10.1021/jacs.8b04763
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发表时间：
2018-08-08
影响因子：
15
通讯作者：
Sun, Hong-Tao
中科院分区：
文献类型：
--
作者：
Yong, Zi-Jun;Guo, Shao-Qang;Sun, Hong-Tao
全无机钙钛矿纳米晶体（NCs）作为新一代低成本的半导体发光系统，在光电子领域得到了广泛的应用。这些纳米材料在绿色和红色光谱范围内的室温光致发光量子产率（PLQYs）接近一致。然而，他们在紫色的plqy要低得多，并且对这种糟糕的性能仍然缺乏深刻的理解。我们报告了一种通过镍离子掺杂工程晶格局部顺序来合成具有近统一PLQYs的所有无机紫色钙钛矿NCs的一般策略。广泛的实验表征，包括稳态和时间分辨发光光谱、x射线吸收光谱和魔角自旋核磁共振光谱，揭示了未掺杂nc中的低PLQY与卤化物空位等内在缺陷引起的晶格的短程无序有关，而Ni掺杂可以大大消除这些缺陷并导致晶格的短程有序增加。密度泛函理论计算表明，钙钛矿的Ni掺杂导致缺陷形成能量增加，并且没有在带隙中引入深阱态，这可能是改善局部结构秩序和近统一PLQY的主要原因。我们获得具有近乎完美性能的紫色钙钛矿NCs的能力，为紫色钙钛矿基器件（如发光二极管、单光子源、激光器等）的一系列应用打开了大门。
All-inorganic perovskite nanocrystals (NCs) have emerged as a new generation of low-cost semiconducting luminescent system for optoelectronic applications. The room-temperature photoluminescence quantum yields (PLQYs) of these NCs in the green and red spectral range approach unity. However, their PLQYs in the violet are much lower, and an insightful understanding of such poor performance remains missing. We report a general strategy for the synthesis of all inorganic violet-emitting perovskite NCs with near-unity PLQYs through engineering local order of the lattice by nickel ion doping. A broad range of experimental characterizations, including steady-state and time-resolved luminescence spectroscopy, X-ray absorption spectra, and magic angle spinning nuclear magnetic resonance spectra, reveal that the low PLQY in undoped NCs is associated with short-range disorder of the lattice induced by intrinsic defects such as halide vacancies and that Ni doping can substantially eliminate these defects and result in increased short-range order of the lattice. Density functional theory calculations reveal that Ni doping of perovskites causes an increase of defect formation energy and does not introduce deep trap states in the band gap, which is suggested to be the main reason for the improved local structural order and near-unity PLQY. Our ability to obtain violet-emitting perovskite NCs with near-perfect properties opens the door for a range of applications in violet-emitting perovskite-based devices such as light-emitting diodes, single-photon sources, lasers, and beyond.