Enhanced performance of OLED based on molecular orientation of emission layer by optimized substrate temperature

Autor: Xiaochen Dong, Shuai Wang, Wenjun Wang, Yunlong Liu, Hui Du, Qianqian Du, Dongyue Cui, Ling Zhao, Shuhong Li
Rok vydání: 2021
Předmět:
Zdroj: Journal of Materials Science: Materials in Electronics. 32:12075-12083
ISSN: 1573-482X
0957-4522
DOI: 10.1007/s10854-021-05836-3
Popis: Horizontally oriented transition dipole moment (TDM) of the molecule in emission layers (EMLs) can boost out-coupling efficiency, resulting in higher performance organic light-emitting diodes (OLEDs). As known, the substrate temperature ( $$T_{s}$$ ) has a significant effect on the TDM of molecules. In this paper, the doped EMLs deposited with different $$T_{s}$$ ranging from 30 to 100 °C were prepared and the corresponding photoluminescence quantum yield (PLQY) and TDM were measured. In addition, these EMLs with different $$T_{s}$$ were employed to the OLED devices. The best luminous efficiency (51.4 cd/A), power efficiency (68.9 lm/W) and external quantum efficiency (EQE) (19.5%) were obtained in the OLED device where EMLs were deposited at 60 °C. However, the anisotropy factor $$\Theta$$ at this temperature is not the best, which is inconsistent with the common rules that high $$\Theta$$ causes high EQE. This phenomenon was ascribed to the in-situ annealing process for the hole transport layer (HTL) during the deposition of EMLs with different $$T_{s}$$ . The synergy of PLQY and TDM orientation of EMLs, the hole mobility of hole only devices (HODs) contribute to the high performance of OLED device at 60 °C.
Databáze: OpenAIRE
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