期刊
ORGANIC ELECTRONICS
卷 94, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.orgel.2021.106169
关键词
Quantum dot light-emitting diodes; All-solution processed; Orthogonal solvent; Hole transport layer; Charge injection balance
资金
- National Key Research and Development Program of China [2016YFB0401702]
- National Natural Science Foundation of China [61775013, 61704007]
- Fundamental Research Funds for the Central Universities [2019YJS195]
This study introduces a synergistical double hole transport layer (D-HTLs) strategy to enhance the efficiency of blue quantum dot light-emitting diodes (QLEDs), achieving a maximum external quantum efficiency (EQE) of 13.7%. The optimization of surface morphology and charge injection balance contributes to the improvement of device performance.
Solution-processed blue quantum dot light-emitting diodes (QLEDs) suffer from low device efficiency, whereas the balance of electron and hole injection is critical for obtaining high efficiency. Herein, synergistical double hole transport layers (D-HTLs) are employed, which use poly(9-vinylcarbazole) (PVK) stacked on poly[(9,9dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB). The fabrication of D-HTLs is achieved by using dimethyl formamide (DMF) as the solvent for PVK, with which the underlying TFB layer almost remains unwashed and undamaged during the spin-coating process of PVK layer. TFB/PVK D-HTLs form the stepwise energy level for hole injection, which reduces the hole injection barrier and favors the carrier balance in the emission layer (EML). The optimized blue QLED with TFB/PVK D-HTLs shows a maximum external quantum efficiency (EQE) of 13.7%, which is 3-fold enhancement compared to that of the control device with single TFB HTL. The enhancement of the QLED performance can be attributed to the improvement of surface morphology and charge injection balance for the stepwise D-HTLs based QLEDs. This work manifests the positive effect on performance boost by selecting appropriate solvents towards stepwise D-HTLs formation and paves the way to fabricate highly efficient all-solution processed light emitting diodes.
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