Premium
Secondary Acceptor Optimization for Full‐Exciton Radiation: Toward Sky‐Blue Thermally Activated Delayed Fluorescence Diodes with External Quantum Efficiency of ≈ 30%
Author(s) -
Li Chenyu,
Duan Chunbo,
Han Chunmiao,
Xu Hui
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201804228
Subject(s) - intersystem crossing , materials science , quantum yield , exciton , acceptor , singlet state , oled , excited state , optoelectronics , radiative transfer , photoluminescence , quantum efficiency , photochemistry , atomic physics , fluorescence , optics , physics , chemistry , nanotechnology , condensed matter physics , layer (electronics)
Efficient blue emitters are indispensable for organic light‐emitting diodes (OLEDs) with respect to display and lighting applications. Because of their high‐energy excited states, both radiation enhancement and non‐radiation suppression should be simultaneously optimized to realize 100% exciton utilization. Here, it is shown that the excited‐state characteristics of blue thermally activated delayed fluorescence emitters can be precisely controlled by a secondary acceptor having moderate electronic effects on increasing the singlet charge‐transfer component and preserving the triplet locally excited‐state component. In addition of planar configuration between the donor and the primary acceptor, the radiative transition improvement and non‐radiative transition suppression can be simultaneously achieved for “full‐exciton radiation”. A molecule using diphenylphosphine oxide as the secondary acceptor exhibits ≈ 100% photoluminescence quantum yield on the basis of its tenfold increased singlet radiative rate constant, fivefold decreased singlet and triplet non‐radiative rate constants, and ≈ 100% reverse intersystem crossing efficiency, which further endows ≈ 100% exciton utilization efficiency to its sky‐blue OLEDs.