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

09 November 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

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.

Keywords

deep red multi-resonance
energy gap law
narrow energy-bandwidth
reddest

Supplementary materials

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Description
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Title
Red BN-Zhang Yuewei
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SI-Red BN
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