Department of Electrical and Computer Engineering , University of Toronto , 10 King's College Road , Toronto , Ontario M5S 3G4 , Canada.
Institute of Applied Physics and Materials Engineering , University of Macau , Macao SAR 999078 , China.
Nano Lett. 2018 May 9;18(5):3157-3164. doi: 10.1021/acs.nanolett.8b00789. Epub 2018 Apr 5.
Lead-halide perovskites have been attracting attention for potential use in solid-state lighting. Following the footsteps of solar cells, the field of perovskite light-emitting diodes (PeLEDs) has been growing rapidly. Their application prospects in lighting, however, remain still uncertain due to a variety of shortcomings in device performance including their limited levels of luminous efficiency achievable thus far. Here we show high-efficiency PeLEDs based on colloidal perovskite nanocrystals (PeNCs) synthesized at room temperature possessing dominant first-order excitonic radiation (enabling a photoluminescence quantum yield of 71% in solid film), unlike in the case of bulk perovskites with slow electron-hole bimolecular radiative recombination (a second-order process). In these PeLEDs, by reaching charge balance in the recombination zone, we find that the Auger nonradiative recombination, with its significant role in emission quenching, is effectively suppressed in low driving current density range. In consequence, these devices reach a maximum external quantum efficiency of 12.9% and a power efficiency of 30.3 lm W at luminance levels above 1000 cd m as required for various applications. These findings suggest that, with feasible levels of device performance, the PeNCs hold great promise for their use in LED lighting and displays.
卤铅钙钛矿因其在固态照明方面的潜在应用而备受关注。继太阳能电池之后，钙钛矿发光二极管（PeLED）领域也得到了快速发展。然而，由于器件性能存在多种缺陷，如目前所能达到的发光效率有限，其在照明方面的应用前景仍不确定。在这里，我们展示了基于室温下合成的胶体钙钛矿纳米晶体（PeNCs）的高效 PeLED，其具有占主导地位的一级激子辐射（在固态薄膜中可实现 71%的光致发光量子产率），与电子空穴双分子辐射复合较慢的体钙钛矿不同（二级过程）。在这些 PeLED 中，通过在复合区达到电荷平衡，我们发现，在低驱动电流密度范围内，具有显著发射猝灭作用的俄歇非辐射复合得到了有效抑制。因此，这些器件在高于 1000 cd m 的亮度水平下，达到了 12.9%的最大外量子效率和 30.3 lm W 的功率效率，满足了各种应用的要求。这些发现表明，在可行的器件性能水平下，PeNCs 在 LED 照明和显示方面具有广阔的应用前景。
