Blue Phosphorescence and Hyperluminescence Generated from Imidazo[4,5-b]pyridin-2-ylidene-Based Iridium(III) Phosphors

作者：Yang, Xilin; Zhou, Xiuwen^*; Zhang, Ye-Xin^*; Li, Deli; Li, Chensen; You, Caifa; Chou, Tai-Che; Su, Shi-Jian^*; Chou, Pi-Tai^*; Chi, Yun^*

来源：Advanced Science, 2022, 9(25): 2201150.

DOI：10.1002/advs.202201150

• carbene
• cyclometalate
• hyperphosphorescence
• iridium
• organic light-emitting diode

Four isomeric, homoleptic iridium(III) metal complexes bearing 5-(trifluoromethyl)imidazo[4,5-b]pyridin-2-ylidene and 6-(trifluoromethyl)imidazo[4,5-b]pyridin-2-ylidene-based cyclometalating chelates are successfully synthesized. The meridional isomers can be converted to facial isomers through acid induced isomerization. The m-isomers display a relatively broadened and red-shifted emission, while f-isomers exhibit narrowed blue emission band, together with higher photoluminescent quantum yields and reduced radiative lifetime relative to the mer-counterparts. Maximum external quantum efficiencies of 13.5% and 22.8% are achieved for the electrophosphorescent devices based on f-tpb1 and m-tpb1 as dopant emitter together with CIE coordinates of (0.15, 0.23) and (0.22, 0.45), respectively. By using f-tpb1 as the sensitizing phosphor and t-DABNA as thermally activated delayed fluorescence (TADF) terminal emitter, hyperluminescent OLEDs are successfully fabricated, giving high efficiency of 29.6%, full width at half maximum (FWHM) of 30 nm, and CIE coordinates of (0.13, 0.11), confirming the efficient Forster resonance energy transfer (FRET) process.

• 单位
  y