近日，瑞士苏黎世应用科学大学的Wolfgang Tress及其研究团队取得一项新进展。经过不懈努力，他们对钙钛矿发光二极管脉冲操作中迁移离子的作用进行研究。相关研究成果已于2024年3月29日在国际知名学术期刊《国家科学评论》上发表。

该研究团队通过漂移扩散模拟，建立了脉冲操作下PeLEDs瞬态电致发光（TrEL）信号与迁移离子影响之间的关联。他们发现，离子缺陷的时变分布可以有效解释TrEL平台值对占空比和脉冲末端超调的依赖关系。因此，在考虑TrEL反应时，必须充分考虑迁移离子的影响。此外，模拟结果还强调了钙钛矿与电荷传输层界面（如他们示例中的空穴传输层HTL）的注入势垒，这是非辐射电荷重组的重要来源。这些发现为我们深入理解钙钛矿基器件中的瞬态离子过程提供了重要线索。

据悉，金属卤化物钙钛矿发光二极管（PeLEDs）是一种极具潜力的技术，在节能和经济高效的照明及显示领域展现出了广阔的应用前景。这得益于其可调的颜色发射、高亮度、颜色纯度高以及低温制造等显著优势。然而，钙钛矿材料中的混合离子-电子电导率问题却给其应用带来了不小的挑战。具体而言，离子缺陷在操作过程中容易重新分布，进而对能量景观和电荷重组机制产生不良影响。

附：英文原文

Title: Pulsed operation of perovskite LEDs: A study on the role of mobile ions

Author: Cachafeiro, Miguel A Torre, Kumawat, Naresh Kumar, Gao, Feng, Tress, Wolfgang

Issue&Volume: 2024-03-29

Abstract: Metal halide perovskite light emitting diodes (PeLEDs) are a promising technology for energy-efficient and cost-effective lighting and displays, thanks to their tunable color emission, high brightness, color purity, and low-temperature fabrication. However, the mixed ionic-electronic conductivity of perovskite materials presents unique challenges, as ionic defects can redistribute under operation, affecting the energy landscape and charge recombination mechanisms. Our drift-diffusion simulations establish a connection between the transient electroluminescence (TrEL) signals of PeLEDs under pulsed operation and the influence of mobile ions. We find that the TrEL plateau value’s dependence on duty cycle and the end-of-pulse overshoot can be explained by the time-varying distribution of ionic defects. The inclusion of mobile ions is crucial to understand the TrEL response. Moreover, the simulations highlight injection barriers at the perovskite/charge-transport layer interfaces, such as is the case for the hole transport layer (HTL) in our example, as a significant source of non-radiative charge recombination. These findings contribute to the understanding of transient ionic processes in perovskite-based devices.

DOI: 10.1093/nsr/nwae128

Source: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwae128/7637789