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<p>Despite the rapid development of organic light-emitting diodes (OLEDs) in the field of displays, obtaining deep-blue OLEDs with high efficiency, small full-width at half-maximum (FWHM), and low efficiency roll-off is still a challenge. Herein, we report a new strategy to develop an efficient and narrow-band deep-blue emitter based on tetradentate Pt(II), labeled <b>PtKW1</b>; this approach involved increasing the <sup>3</sup>LE character of the lowest triplet state (T<sub>1</sub>) by extending the π conjugation in the carbazole moiety, followed by locking the N-heterocyclic carbene (NHC) and phenyl moiety with a six-membered alkyl ring, aiming to enhance the molecular rigidity. Satisfactorily, <b>PtKW1</b> showed a low Huang-Rhys factor (S<sub>M</sub>) value of 0.285 and an FWHM of only 18.4 nm in dichloromethane at room temperature. Furthermore, a <b>PtKW1</b>-doped exciplex host film exhibited a quantum efficiency of up to 99% and a short excited state lifetime of 3.17 μs. A <b>PtKW1</b>-doped deep-blue OLED achieved an FWHM of 26 nm, Commission Internationale de l’Eclairage (CIE) coordinates of (0.125, 0.189), a maximum luminescent brightness (<i>L</i><sub>max</sub>) of up to 41074 cd/m<sup>2</sup>, and a maximum external quantum efficiency (EQE<sub>max</sub>) of 27.4%, with a low-efficiency roll-off rate of only 1.46% at 1000 cd/m<sup>2</sup>. This work provides new insights for designing robust, narrow-band tetradentate Pt(II) emitters to develop highly efficient and stable deep-blue OLEDs with low efficiency roll-off and high luminescence.</p>

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Rigidity-enhanced tetradentate Pt(II) emitter via π-extension and ring-locking strategy for high-performance deep-blue OLED

  • 期刊论文

  • 发表日期：

    2025年9月26日

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  • Kewei Xu,
  • Jianqiang Chen,
  • Chengyao Zhang,
  • Weiwei Lou,
  • Yun-Fang Yang,
  • Yuanbin She,
  • Guijie Li

摘要

Despite the rapid development of organic light-emitting diodes (OLEDs) in the field of displays, obtaining deep-blue OLEDs with high efficiency, small full-width at half-maximum (FWHM), and low efficiency roll-off is still a challenge. Herein, we report a new strategy to develop an efficient and narrow-band deep-blue emitter based on tetradentate Pt(II), labeled PtKW1; this approach involved increasing the 3LE character of the lowest triplet state (T1) by extending the π conjugation in the carbazole moiety, followed by locking the N-heterocyclic carbene (NHC) and phenyl moiety with a six-membered alkyl ring, aiming to enhance the molecular rigidity. Satisfactorily, PtKW1 showed a low Huang-Rhys factor (SM) value of 0.285 and an FWHM of only 18.4 nm in dichloromethane at room temperature. Furthermore, a PtKW1-doped exciplex host film exhibited a quantum efficiency of up to 99% and a short excited state lifetime of 3.17 μs. A PtKW1-doped deep-blue OLED achieved an FWHM of 26 nm, Commission Internationale de l’Eclairage (CIE) coordinates of (0.125, 0.189), a maximum luminescent brightness (Lmax) of up to 41074 cd/m2, and a maximum external quantum efficiency (EQEmax) of 27.4%, with a low-efficiency roll-off rate of only 1.46% at 1000 cd/m2. This work provides new insights for designing robust, narrow-band tetradentate Pt(II) emitters to develop highly efficient and stable deep-blue OLEDs with low efficiency roll-off and high luminescence.