High-performance blue OLED using multiresonance thermally activated delayed fluorescence host materials containing silicon atoms

We report three highly efficient multiresonance thermally activated delayed fluorescence blue-emitter host materials that include 5,9-dioxa-13b-boranaphtho[3,2,1- de ]anthracene (DOBNA) and tetraphenylsilyl groups. The host materials doped with the conventional N 7 , N 7 , N 13 , N 13 ,5,9,11,15-octaphenyl-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diboradinaphtho[3,2,1- de :1’,2’,3’- jk ]pentacene-7,13-diamine ( ν -DABNA) blue emitter exhibit a high photoluminescence quantum yield greater than 0.82, a high horizontal orientation greater than 88%, and a short photoluminescence decay time of 0.96–1.93 μs. Among devices fabricated using six synthesized compounds, the device with (4-(2,12-di- tert -butyl-5,9-dioxa-13 b -boranaphtho[3,2,1- de ]anthracen-7-yl)phenyl)triphenylsilane (TDBA-Si) shows high external quantum efficiency values of 36.2/35.0/31.3% at maximum luminance/500 cd m −2 /1,000 cd m −2 . This high performance is attributed to fast energy transfer from the host to the dopant. Other factors possibly contributing to the high performance are a T 1 excited-state contribution, inhibition of aggregation by the bulky tetraphenylsilyl groups, high horizontal orientation, and high thermal stability. We achieve a high efficiency greater than 30% and a small roll-off value of 4.9% at 1,000 cd m −2 using the TDBA-Si host material. Effective energy transfer and suppressed dopant aggregation is critical for realizing efficient organic light-emitting diodes. Here, the authors report six host materials capable of exhibiting enhanced thermal stability and film-formation behavior, demonstrating efficiency of over 30% at 1000 cd/m 2 .