[13a-B11-1~10] 12.4 Organic light-emitting devices and organic transistors

△ [13a-B11-7] High-efficiency green TADF OLED realizing over 20% EQE by an isonicotinonitrile / phenoxazine conjugate emitter

〇(M2)Natsuki Onuma¹, Hisahiro Sasabe^2,3, Yuji Nagai¹, Takashi Ito⁴, Junji Kido^2,3 (1.Org. Dev. Eng., 2.Org. Mater. Sci., 3.ROEL, 4.Yamagata Univ. Eng.)

Keywords:organic light-emitting devices, thermally activated delayed fluorescence

In this work, we designed and synthesized a novel isonicotinonitrile/phenoxazine-based green thermally activated delayed fluorescence (TADF) emitter named PXZINN for high-performance TADF organic light- emitting devices (OLEDs). The ionization potential of PXZINN was observed at 5.6 eV, whereas, the electron affinity was estimated to be 3.1 eV. The energy difference between singlet and triplet excited states was observed to be 0.06 eV. The photoluminescent quantum yield (PLQY) of the 10 wt% PXZINN-doped 4,4'-bis(carbazol-9-yl)biphenyl (CBP) film was observed to be 79% with an emission peak at 522 nm. An OLED with a structure of [ITO/triphenylamine- containing polymer: 4-isopropyl-4′-methyldiphenyl-iodonium tetrakis(pentafluorophenyl)borate (PPBI)/di-[4-(N,N- ditolyl-amino)-phenyl]cyclohexane (TAPC)/PXZINN-doped CBP/3,3'’,5,5'-tetra(3-pyridyl)-1,1’;3’,1''-terphenyl (B3PyPB)/LiF/Al] were fabricated. The device exhibited operating voltages of 2.84, and 3.39 V at luminances of 1 and 100 cd m–2, respectively. At 100 cd m–2, this device gave a power efficiency of 67.4 lm W–1, a current efficiency of 72.7 cd A–1, an external quantum efficiency of 22%.