Zhang Dezhong, Fu Yunxing, Zhan Hongmei, Zhao Chenyang, Gao Xiang, Qin Chuanjiang, Wang Lixiang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, China.
Light Sci Appl. 2022 Mar 23;11(1):69. doi: 10.1038/s41377-022-00761-4.
Emission thermal quenching is commonly observed in quasi-2D perovskite emitters, which causes the severe drop in luminescence efficiency for the quasi-2D perovskite light-emitting diodes (PeLEDs) during practical operations. However, this issue is often neglected and rarely studied, and the root cause of the thermal quenching has not been completely revealed now. Here, we develop a passivation strategy via the 2,7-dibromo-9,9-bis (3'-diethoxylphosphorylpropyl)-fluorene to investigate and suppress the thermal quenching. The agent can effectively passivate coordination-unsaturated Pb defects of both surface and bulk of the film without affecting the perovskite crystallization, which helps to more truly demonstrate the important role of defects in thermal quenching. And our results reveal the root cause that the quenching will be strengthened by the defect-promoted exciton-phonon coupling. Ultimately, the PeLEDs with defect passivation achieve an improved external quantum efficiency (EQE) over 22% and doubled operation lifetime at room temperature, and can maintain about 85% of the initial EQE at 85 °C, much higher than 17% of the control device. These findings provide an important basis for fabricating practical PeLEDs for lighting and displays.
发射热猝灭在准二维钙钛矿发光体中普遍存在，这导致准二维钙钛矿发光二极管（PeLEDs）在实际运行过程中发光效率严重下降。然而，这个问题常常被忽视且很少被研究，热猝灭的根本原因至今尚未完全揭示。在此，我们通过2,7-二溴-9,9-双（3'-二乙氧基磷酰基丙基）芴开发了一种钝化策略，以研究和抑制热猝灭。该试剂可以有效钝化薄膜表面和体相的配位不饱和Pb缺陷，而不影响钙钛矿的结晶，这有助于更真实地证明缺陷在热猝灭中的重要作用。我们的结果揭示了根本原因，即缺陷促进的激子-声子耦合会增强猝灭。最终，具有缺陷钝化的PeLEDs在室温下实现了超过22%的外量子效率（EQE）提升和运行寿命翻倍，并且在85°C时可以保持约85%的初始EQE，远高于对照器件的17%。这些发现为制造用于照明和显示的实用PeLEDs提供了重要依据。
