Bis-Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue-Emitting OLEDs

Hsin-Hung Kuo; Ze-Lin Zhu; Chun-Sing Lee; Yi-Kuang Chen; Shih-Hung Liu; Pi-Tai Chou; Alex K-Y Jen; Yun Chi

doi:10.1002/advs.201800846

Bis-Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue-Emitting OLEDs

Adv Sci (Weinh). 2018 Jul 31;5(9):1800846. doi: 10.1002/advs.201800846. eCollection 2018 Sep.

Authors

Hsin-Hung Kuo¹, Ze-Lin Zhu², Chun-Sing Lee², Yi-Kuang Chen¹, Shih-Hung Liu³, Pi-Tai Chou³, Alex K-Y Jen⁴, Yun Chi^{1

4}

Affiliations

¹ Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan.
² Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry City University of Hong Kong Hong Kong SAR.
³ Department of Chemistry National Taiwan University Taipei 10617 Taiwan.
⁴ Department of Materials Science and Engineering and Department of Chemistry City University of Hong Kong Hong Kong SAR.

Abstract

Sky-blue and blue-emitting, carbazolyl functionalized, bis-tridentate Ir(III) phosphors Cz-1-Cz-3 with bright emission and short radiative lifetime are successfully synthesized in a one-pot manner. They exhibit very high photostability against UV-vis irradiation in degassed toluene, versus both green and true-blue-emitting reference compounds, i.e., fac-[Ir(ppy)₃] and mer-[Ir(pmp)₃]. Organic light-emitting diodes (OLEDs) based on Cz-2 exhibit maximum external quantum efficiency (EQE) of 21.6%, EQE of 15.1% at 100 cd m^-2, and with CIE _x_,_y coordinates of (0.17, 0.25). This study provides a conceptual solution to the exceedingly stable and efficient blue phosphor. It is promising that long lifespan blue OLED based on these emitters can be attained with further engineering of devices suitable for commercial application.

Keywords: N‐heterocyclic carbene (NHC); bis‐tridentate; carbazole; iridium; pyrazolate.