Synthesis and Electroluminescent Properties of Through-Space Charge Transfer Polymers Containing Acridan Donor and Triarylboron Acceptors.

Fan Chen,Fosong Wang,Jun Hu,Lixiang Wang,Xiabin Jing,Xingdong Wang,Shiyang Shao

doi:10.3389/fchem.2019.00854

Abstract

We report the design, synthesis and electroluminescent properties of three kinds of through-space charge transfer (TSCT) polymers consisting of non-conjugated polystyrene backbone, acridan donor and triarylboron acceptors having different substituents such as hydrogen (H), fluorine (F), and trifluoromethyl (CF3). Owing to the weak electron interaction between acridan donor and triarylboron acceptor through non-conjugated connection, blue emission with peaks in range of 429–483 nm can be achieved for the polymers in solid-state film, accompanied with photoluminescence quantum yields of 26–53%. The resulting TSCT polymers exhibit small ΔEST values below 0.1 eV owing to the separated HOMO and LUMO distributions, showing thermally activated delayed fluorescence with lifetimes in range of 0.19–0.98 μs. Meanwhile, the polymers show aggregation-induced emission (AIE) effect with the emission intensity increased by up to ~33 folds from solution to aggregation state. Solution-processed organic light-emitting diodes based on the polymers containing trifluoromethyl substituent exhibit promising electroluminescent performance with maximum luminous efficiency of 20.1 cd A−1 and maximum external quantum efficiency of 7.0%, indicating that they are good candidates for development of luminescent polymers.

Highlights

Charge transfer (CT) is a crucial process in determining the emission behaviors of luminescent materials (Muller et al, 2003; Wu et al, 2004; Yuan et al, 2012; Liu et al, 2018; Sarma and Wong, 2018; Li J. et al, 2019)
By modulating the CT strength through introducing substituents with different electron-accepting capability, through-space charge transfer (TSCT) polymers with emission color ranging from deep-blue to red can be realized with external quantum efficiency (EQE) up to 16.2%, suggesting their potential in development of novel luminescent materials for solutionprocessed organic light-emittingThrough-Space Charge Transfer Polymer diodes (OLEDs)
The triarylboron units are used as acceptors because of their weak electron-accepting capability which is favorable for realizing blue emission

Summary

INTRODUCTION

Charge transfer (CT) is a crucial process in determining the emission behaviors of luminescent materials (Muller et al, 2003; Wu et al, 2004; Yuan et al, 2012; Liu et al, 2018; Sarma and Wong, 2018; Li J. et al, 2019). By modulating the CT strength through introducing substituents with different electron-accepting capability, TSCT polymers with emission color ranging from deep-blue to red can be realized with external quantum efficiency (EQE) up to 16.2%, suggesting their potential in development of novel luminescent materials for solutionprocessed OLEDs. Recently triarylborons have been attractive building blocks for luminescent materials with CT character because of their promising electron-accepting properties endowed by the vacant p-orbitals of central boron atoms that can participate in πconjugation with aryl groups (Hirai et al, 2015; Numata et al, 2015; Suzuki et al, 2015; Hatakeyama et al, 2016; Wu et al, 2018; Ahn et al, 2019; Kondo et al, 2019; Mellerup and Wang, 2019). Solution-processed organic light-emitting diodes (OLEDs) based on the triarylboron-containing polymers show maximum EQEs up to 7.0%, indicating that they are promising candidates for development of luminescent polymers

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT