Charge‐Transfer Exciton Manipulation Based on Hydrogen Bond for Efficient White Thermally Activated Delayed Fluorescence. (29th December 2019)

• Record Type: Journal Article
• Authors: Sun, Jianan; Zhang, Jing; Liang, Qianqian; Wei, Ying; Duan, Chunbo; Han, Chunmiao; Xu, Hui
• Is Part Of: Advanced functional materials. Volume 30:Number 9(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-12-29
• Subjects: charge transfer exciton -- exciton allocation -- hydrogen bond -- thermally activated delayed fluorescence -- white organic light‐emitting diodes; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201908568
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Despite the success of thermally activated delayed fluorescence (TADF) emitters in monochromatic organic light‐emitting diodes (OLED), only few efficient full‐TADF white OLEDs (WOLED) are reported because of the challenge in rational exciton allocation between blue and other color emitters. Herein, it is demonstrated that the appropriate exciton delocalization in blue TADF matrixes can simultaneously support the sufficient blue emission and the energy loss–free charge and exciton transfer to yellow TADF emitters. Through introducing steric hindrance–modulated intermolecular hydrogen bond networks, a fluorinated carbazole‐phosphine oxide hybrid realizes the balance of exciton localization and delocalization, giving rise to state‐of‐the‐art external quantum efficiency beyond 20% from its simple trilayer full‐TADF WOLEDs, accompanied by excellent spectral stability. The correlation between the efficiencies of the blue TADF matrixes and their intermolecular interactions reveals that the exciton delocalization is crucial for the exciton allocation optimization in multicomponent emission systems. Abstract : White organic light‐emitting diodes (WOLED) based on full thermally activated delayed fluorescence (TADF) systems are optmized by charge‐transfer exciton manipulation for optimal exciton allocation. Through introducing steric hindrance–modulated hydrogen bond networks, exciton delocalization in the blue matrix is optimized to balance the blue and yellow emissions for state‐of‐the‐art external quantum efficiency beyond 20%, and excellent white light stability.