Elucidating the Role of Substrates on Domain Distribution of Quasi-2D Perovskites for Blue Light-Emitting Diodes,ACS Applied Electronic Materials

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Elucidating the Role of Substrates on Domain Distribution of Quasi-2D Perovskites for Blue Light-Emitting Diodes
ACS Applied Electronic Materials ( IF 4.3 ) Pub Date : 2021-09-07 , DOI: 10.1021/acsaelm.1c00556
Jinqiao Cai ₁ , Muhammad Umair Ali ₂ , Jinhao Xu ₁ , Jingsheng Miao ₁ , Jingwei Chen ₁ , Ming Liu ₁ , Qi Wei ₃ , Guichuan Xing ₃ , Hong Meng ₁

Affiliation

Perovskite light-emitting diodes (PeLEDs) have been developed at a rapid pace with high external quantum efficiencies (EQEs) surpassing 20% for red, infrared, and green emissions; nevertheless, the performance of their blue-emitting cousins remains relatively quite low. Among various crucial factors that could impact these solution-processed devices, selection of a suitable underlayer (usually a hole-transport layer) is critical to the quality of resulting perovskite films. Particularly, the role of the substrate is highly important in the case of quasi-2D perovskite films where the emission occurs as a result of cascade energy transfer among various perovskite domains with different numbers of lead-halide octahedral layers (n) sandwiched between long-chain organic molecules. Herein, we explored the impact of the substrate on domain distribution of quasi-2D perovskite films, and a series of efficient and color-stable blue PeLEDs is attained through precise stoichiometric engineering. By employing a range of characterization tools, we thoroughly investigated the crystallization mechanism of quasi-2D perovskites on different substrates, including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and poly[(9,9-dioctylfluorenyl-2,7-diyl)- co -(4,4′-( N -(4-sec-butylphenyl)diphenylamine)] (TFB). Perovskite films spin-coated on PEDOT:PSS exhibited cyan emission from the n ≥ 4 quasi-2D phase with uniformly distributed small grains. In contrast, perovskite layers formed on TFB featured an island morphology and showed blue emission from the quasi-2D phase with n-values between 2 and 4. In addition, we examined how the variation of A-site cations affects the optical properties of quasi-2D perovskites. Consequently, PEDOT:PSS-based champion PeLED exhibited cyan emission at 495 nm with a maximum EQE of 6.73%, whereas TFB-based counterparts manifested blue emission at 486 nm with a peak EQE of 3.95%. We anticipate that our work will provide a fundamental guideline to rationally selecting the substrates for the optimized growth of quasi-2D perovskites toward high-efficiency PeLEDs.

中文翻译：

阐明衬底对蓝光发光二极管准二维钙钛矿畴分布的作用

钙钛矿发光二极管 (PeLED) 发展迅速，具有高外量子效率 (EQE)，红光、红外光和绿光发射超过 20%；尽管如此，它们发出蓝光的表亲的性能仍然相对较低。在可能影响这些溶液处理设备的各种关键因素中，选择合适的底层（通常是空穴传输层）对于所得钙钛矿薄膜的质量至关重要。特别是，在准二维钙钛矿薄膜的情况下，基板的作用非常重要，其中发射是由于具有不同数量的卤化铅八面体层（n) 夹在长链有机分子之间。在此，我们探索了基板对准二维钙钛矿薄膜畴分布的影响，并通过精确的化学计量工程获得了一系列高效且颜色稳定的蓝色 PeLED。通过使用一系列表征工具，我们彻底研究了准二维钙钛矿在不同基材上的结晶机制，包括聚（3,4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT：PSS）和聚[（9,9-二辛基芴基-2,7-二基)- co -(4,4'-( N -(4-sec-butylphenyl)diphenylamine)] (TFB). 旋涂在 PEDOT:PSS 上的钙钛矿薄膜表现出来自n 的青色发射≥ 4 个具有均匀分布的小晶粒的准二维相。相比之下，在 TFB 上形成的钙钛矿层具有岛状形态，并从准 2D 相显示蓝色发射，n 值在 2 和 4 之间。此外，我们研究了 A 位阳离子的变化如何影响准二维相的光学性质。 -2D 钙钛矿。因此，基于 PEDOT:PSS 的冠军 PeLED 在 495 nm 处表现出青色发射，最大 EQE 为 6.73%，而基于 TFB 的对应物在 486 nm 处表现出蓝色发射，峰值 EQE 为 3.95%。我们预计我们的工作将为合理选择基板以优化准二维钙钛矿向高效 PeLED 生长提供基本指导。

更新日期：2021-09-28

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