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Multi‐Resonance Deep‐Red Emitters with Shallow Potential‐Energy Surfaces to Surpass Energy‐Gap Law **
Author(s) -
Zhang Yuewei,
Zhang Dongdong,
Huang Tianyu,
Gillett Alexander J.,
Liu Yang,
Hu Deping,
Cui Linsong,
Bin Zhengyang,
Li Guomeng,
Wei Jinbei,
Duan Lian
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202107848
Subject(s) - delocalized electron , resonance (particle physics) , excited state , atomic orbital , band gap , luminescence , chemistry , atomic physics , molecular physics , photochemistry , materials science , optoelectronics , physics , organic chemistry , quantum mechanics , electron
Efficient organic emitters in the deep‐red region are rare due to the “energy gap law”. Herein, multiple boron (B)‐ and nitrogen (N)‐atoms embedded polycyclic heteroaromatics featuring hybridized π‐bonding/ non‐bonding molecular orbitals are constructed, providing a way to overcome the above luminescent boundary. The introduction of B‐phenyl‐B and N‐phenyl‐N structures enhances the electronic coupling of those para‐positioned atoms, forming restricted π‐bonds on the phenyl‐core for delocalized excited states and thus a narrow energy gap. The mutually ortho‐positioned B‐ and N‐atoms also induce a multi‐resonance effect on the peripheral skeleton for the non‐bonding orbitals, creating shallow potential energy surfaces to eliminate the high‐frequency vibrational quenching. The corresponding deep‐red emitters with peaks at 662 and 692 nm exhibit narrow full‐width at half‐maximums of 38 nm, high radiative decay rates of ca. 10 8 s −1 , ≈100 % photo‐luminescence quantum yields and record‐high maximum external quantum efficiencies of ca. 28 % in a normal planar organic light‐emitting diode structure, simultaneously.