Self-Organized Carbazole Phosphonic Acid Additives at Buried Interface Enhance Efficiency of Blue Perovskite LEDs
Guangruixing Zou, Zhaohua Zhu, Zixin Zeng, Zhiqiang Guan, Nan Zhang, Wenlin Jiang, Ziming Chen, Ye Wu, Desui Chen, Francis Lin, Sai‐Wing Tsang, Chun‐Sing Lee, Andrey L. Rogach, Alex K.‐Y. Jen, Hin‐Lap Yip
Abstract
Carbazole phosphonic acids (CPAs) that are used in self-assembled monolayers (SAMs) are well-reported. Yet, an understanding of their broader application still needs to be fully established. In this work, we demonstrate that incorporating CPAs into blue quasi-2D perovskite precursors as additives is an effective strategy for fine-tuning phase distribution and enhancing the radiative characteristics of the resultant films. [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid (2PACz) emerges as the most effective molecule for improving device performance. Significantly, when the perovskite film is deposited onto a hole injection structure of ITO/Mg 0.1 Ni 0.9 O x /SAM/poly(9-vinylcarbazole) (PVK), 2PACz preferentially migrates to the PVK/perovskite interface. This phenomenon is driven by the strong interaction between the carbazole components of both PVK and 2PACz, leading to a stabilized interface. Coupled with the controlled phase distribution of the perovskite, this approach results in a marked increase in external quantum efficiency for blue perovskite LEDs, advancing from 11% to beyond 15%. These insights underscore the versatility of CPAs in the development of high-efficiency optoelectronic devices.