Water‐Soluble Conjugated Polyelectrolyte Hole Transporting Layer for Efficient Sky‐Blue Perovskite Light‐Emitting Diodes

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 17; no. 37; pp. e2101477 - n/a
• Main Authors: Liu, Yanliang, Zhang, Luozheng, Chen, Shi, Liu, Chang, Li, Yaru, Wu, Jiawen, Wang, Deng, Jiang, Zhengyan, Li, Yan, Li, Yang, Wang, Xingzhu, Xu, Baomin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.09.2021
• Subjects: conjugated polyelectrolyte; Crystal defects; Energy transfer; hole transporting layer; interface defect; Morphology; Nanotechnology; Perovskites; Photoelectricity; Photoluminescence; Polyelectrolytes; Quantum efficiency; quasi‐2D perovskite film; sky‐blue PeLEDs; Substrates
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202101477

An optimized charge transporting layer (CTL) under perovskite film is crucial for efficient photoelectric devices. Here, a new water‐soluble conjugated polyeletrolyte (CPE) with CH3NH3+ (MA+) counterion termed as TB(MA) is used as the hole transporting layer (HTL) instead of the acidic poly(3,4‐ethylenedioxythiophene):poly‐styrene sulfonate (PEDOT:PSS) in sky‐blue perovskite light‐emitting diodes (PeLEDs). The inherent hydrophilicity of CPE enables a well‐growth of quasi‐2D perovskite layer with uniform and compact morphology, enhanced crystallinity with rare defect density and excellent energy transfer, resulting in a high photoluminescence quantum yield (PLQY) up to 62.0%. Especially, the MA+ counterion is able to passivate the interfacial defects in the perovskite, which optimize the interfacial compatibility between HTL and perovskite film. Finally, efficient sky‐blue PeLEDs, emitting at 488 nm, are fabricated with high external quantum efficiency (EQE) up to 13.5% by using CPE as HTL. In addition, due to the low‐temperature processability of water‐soluble CPE, an efficient flexible sky‐blue PeLEDs based on PEN/ITO substrate is also obtained with high EQE of 8.3%. Using CPE as HTL is an effective strategy toward fabricating efficient blue PeLEDs. The conjugated polyeletrolyte (CPE) of TB(MA) is used as HTL instead of the acidic poly(3,4‐ethylenedioxythiophene):poly‐styrene sulfonate (PEDOT:PSS) in sky‐blue perovskite light‐emitting diodes (PeLEDs). The TB(MA) based quasi‐2D perovskite films possess excellent optical properties with lower defect density, improved PLQY and TR‐PL life‐time, and fast energy transfer process, resulting in high‐performance PeLED. An efficient sky‐blue PeLEDs, emitting at 488 nm, is fabricated with high external quantum efficiency (EQE) up to 13.5% by using CPE as hole transporting layer (HTL).