Balancing the electron and hole transfer for efficient quantum dot light-emitting diodes by employing a versatile organic electron-blocking layer

Xiao Jin, Chun Chang, Weifeng Zhao, Shujuan Huang*, Xiaobing Gu, Qin Zhang, Feng Li, Yubao Zhang, Qinghua Li

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The electron-blocking layer (EBL) is important to balance the charge carrier transfer and achieve highly efficient quantum dot light-emitting diodes (QLEDs). Here, we report the utilization of a soluble tert-butyldimethylsilyl chloride-modified poly(p-phenylene benzobisoxazole) (TBS-PBO) as an EBL for simultaneous good charge carrier transfer balance while maintaining a high current density. We show that the versatile TBS-PBO blocks excess electron injection into the quantum dots (QDs), thus leading to better charge carrier transfer balance. It also restricts the undesired QD-to-EBL electron-transfer process, which preserves the superior emission capabilities of the emitter. As a consequence, the TBS-PBO device delivers an external quantum efficiency (EQE) maximum of 16.7% along with a remarkable current density as high as 139 mA/cm2 with a brightness of 5484 cd/m2. The current density of our device is higher than those of insulator EBL-based devices because of the higher conductivity of the TBS-PBO versus insulator EBL, thus helping achieve high luminance values ranging from 1414 to 20 000 cd/cm2 with current densities ranging from 44 to 648 mA/cm2 and EQE > 14%. We believe that these unconventional features of the present TBS-PBO-based QLEDs will expand the wide use of TBS-PBO as buffer layers in other advanced QLED applications.

Original languageEnglish
Pages (from-to)15803-15811
Number of pages9
JournalACS Applied Materials and Interfaces
Volume10
Issue number18
DOIs
Publication statusPublished - 9 May 2018
Externally publishedYes

Keywords

  • quantum dot light-emitting diodes
  • TBS-PBO
  • charge-transfer balance
  • electron-blocking layer
  • time-resolved PL

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