LAUSR

Several thermally activated delayed fluorescence (TADF) materials have been studied and developed to realize high-performance organic light-emitting diodes (OLEDs). However, TADF macrocycles have not been sufficiently investigated owing to the synthetic challenges, resulting in limited exploration of their luminescent properties and the corresponding highly efficient OLEDs. In this study, a series of TADF macrocycles w ere synthesized using a modularly tunable strategy by introducing xanthones as acceptors and phenylamine derivatives as donors. A detailed analysis of their photophysical properties combined with fragment molecules revealed characteristics of high-performance macrocycles. The results indicated that (a) the ideal structure decreased the energy loss, which in turn reduced the non-radiative transitions; (b) reasonable building blocks increase the oscillator strength providing a higher radiation transition rate; (c) the horizontal dipole orientation (Θ) of extended macrocyclic emitters w as increased. Owing to the high photoluminescence quantum yields of approximately 100 and 92% and excellent Θ of 80 and 79% for macrocycles MC-X and MC-XT in 5 wt% doped films, the corresponding devices exhibited record-high external quantum efficiencies of 31.6 and 26.9%, respectively, in the field of TADF macrocycles. This article is protected by copyright. All rights reserved.