Achieving phthalide-based fluorescent materials with hybridized local and charge-transfer characteristics for efficient deep blue OLEDs

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024-03, Vol.12 (11), p.3881-3887
• Main Authors: Feng, Zijun, Liu, Futong, Cheng, Zhuang, Ge, Shuyuan, Wang, Yaxue, Yan, Zhenyu, Ma, Xiaobo, Wang, Yan, Lu, Ping
• Format: Article
• Language: English
• Subjects: Anthracene; Charge transfer; Efficiency; Emitters; Excitation; Excitons; Fluorescence; Quantum efficiency
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d4tc00121d

The development of high-efficiency blue organic light-emitting materials is of significant importance for future illumination and display applications. In this work, three blue emitters, PPT , PPPT and PAPT with D-A/D-π-A architectures have been developed, in which phthalide was first adopted as a functional acceptor. As revealed by theoretical calculations and photophysical experiments, PPT , PPPT and PAPT all display a certain degree of orbital overlap of the local excited state and exhibit typical hybridized local and charge-transfer (HLCT) characteristics. The multiple supramolecular interactions induced by phthalides endow them with high PLQYs. PAPT with the π bridge of anthracene exerts the advantages of the LE-dominated HLCT excited state and high-lying reverse intersystem crossing (hRISC) via a hot exciton channel to obtain the highest PLQY and external quantum efficiency (EQE). As a result, the PAPT -based non-doped device achieved the maximum EQE of 7.5% at a high luminance of 1800 cd m −2 . Particularly, the doped device based on PAPT exhibited superior performance with the maximum EQE of 10.2% and CIE coordinates of (0.151, 0.085), and the full width at half maximum (FWHM) was determined to be only 53 nm. The results offer a simple and efficient approach for engineering D-A/D-π-A type HLCT materials to achieve high-efficiency deep blue OLEDs. Three blue emitters, PPT , PPPT and PAPT with D-A/D-π-A architectures have been developed, in which phthalide was first adopted as a functional acceptor. The device based on PAPT exhibited maximum EQE of 10.2% and FWHM of 53 nm.