The Origin of the Improved Efficiency and Stability of Triphenylamine‐Substituted Anthracene Derivatives for OLEDs: A Theoretical Investigation

Herein, we describe the molecular electronic structure, optical, and charge‐transport properties of anthracene derivatives computationally using density functional theory to understand the factors responsible for the improved efficiency and stability of organic light‐emitting diodes (OLEDs) with triphenylamine (TPA)‐substituted anthracene derivatives. The high performance of OLEDs with TPA‐substituted anthracene is revealed to derive from three original features in comparison with aryl‐substituted anthracene derivatives: 1) the HOMO and LUMO are localized separately on TPA and anthracene moieties, respectively, which leads to better stability of the OLEDs due to the more stable cation of TPA under a hole majority‐carrier environment; 2) the more balanceable hole and electron transport together with the easier hole injection leads to a larger rate of hole–electron recombination, which corresponds to the higher electroluminescence efficiency; and 3) the increasing reorganization energy for both hole and electron transport and the higher HOMO energy level provide a stable potential well for hole trapping, and then trapped holes induce a built‐in electric field to prompt the balance of charge‐carrier injection. Let there be more light! TPA‐substituted anthracene derivatives result in stable organic light‐emitting diodes. The more balanceable hole and electron transport in TPA‐substituted anthracene, together with the easier hole‐injection and hole‐trapping mechanism, leads to high electroluminescence efficiency (see picture; ETL: electron transport layer; HTL: hole transport layer).