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Beating the Limitation of Energy Gap Law Utilizing Deep Red MR-TADF Emitter with Narrow Energy-Bandwidth

submitted on 06.11.2020, 20:44 and posted on 09.11.2020, 12:55 by Yuewei Zhang, Dongdong Zhang, Tianyu Huang, Guomeng Li, Chen Zhang, Yang Lu, Ziyang Liu, Lian Duan

The development of high-performance deep red/near-infrared organic light-emitting diodes is hindered by strong non-radiative processes as governed by the energy gap law. Herein, a novel BN-containing skeleton featuring linear N-π-N and B-π-B structure is developed, establishing partial bonding/antibonding character on phenyl core for enhanced electronics coupling of para-positioned B atoms as well as N atoms to narrow energy gaps. Also, the remained MR effect on the peripheral skeleton to maintain the MR effect to minimize the bonding/ antibonding character and suppress vibrational coupling between S0 and S1, thereby fundamentally overcoming the luminescent boundary set by the energy gap law. The target molecules R-BN and R-TBN exhibited extremely high PLQYs of 100% with emission wavelengths at 666 and 686 nm, respectively. The narrow FWMHs of 38 nm observed also testify the effectiveness of vibronic suppression. The corresponding OLEDs afford record-high EQEs over 28% with emission wavelength over 664 nm.


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Tsinghua University



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Declaration of Conflict of Interest

The authors declare no competing interests.