Rational Design of π-Conjugated Tricoordinated Organoboron Derivatives With Thermally Activated Delayed Fluorescent Properties for Application in Organic Light-Emitting Diodes

Ruifa Jin; Jingfan Xin

doi:10.3389/fchem.2020.577834

Rational Design of π-Conjugated Tricoordinated Organoboron Derivatives With Thermally Activated Delayed Fluorescent Properties for Application in Organic Light-Emitting Diodes

Front Chem. 2020 Sep 30:8:577834. doi: 10.3389/fchem.2020.577834. eCollection 2020.

Authors

Ruifa Jin^{1

2}, Jingfan Xin^{1

2}

Affiliations

¹ College of Chemistry and Life Sciences, Chifeng University, Chifeng, China.
² Inner Mongolia Key Laboratory of Photoelectric Functional Materials, Chifeng University, Chifeng, China.

Abstract

A series of donor-acceptor (D-A) tricoordinated organoboron derivatives (1-10) have been systematically investigated for thermally activated delayed fluorescent (TADF)-based organic light-emitting diode (OLED) materials. The calculated results show that the designed molecules exhibit small singlet-triplet energy gap (ΔE _ST) values. Density functional theory (DFT) analysis indicated that the designed molecules display an efficient separation between donor and acceptor fragments because of a small overlap between donor and acceptor fragments on HOMOs and LUMOs. Furthermore, the delayed fluorescence emission color can be tuned effectively by introduction of different polycyclic aromatic fragments in parent molecule 1. The calculated results show that molecules 2, 3, and 4 possess more significant Stokes shifts and red emission with small ΔE _ST values. Nevertheless, other molecules exhibit green (1, 7, and 8), light green (6 and 10), and blue (5 and 9) emissions. Meanwhile, they are potential ambipolar charge transport materials except that 4 and 10 can serve as electron and hole transport materials only, respectively. Therefore, we proposed a rational way for the design of efficient TADF materials as well as charge transport materials for OLEDs simultaneously.

Keywords: organic light-emitting diodes (OLEDs); photophysical properties; reorganization energy; thermally activated delayed fluorescent (TADF); tricoordinated organoboron derivatives.