Issue 38, 2022

Rational molecular design of phenanthroimidazole-based fluorescent materials towards high-efficiency non-doped deep blue OLEDs

Abstract

Achieving high external quantum efficiency (EQE) for non-doped deep blue fluorescent organic light-emitting diodes (OLEDs) with the Commission International de I'Eclairage (CIE) coordinate of CIEy < 0.08 remains a big challenge. Herein, three high-efficiency molecules PPI-2-DMF, PPI-2-DPF and PPI-3-SBF with weak intramolecular charge transfer properties are successfully prepared by connecting phenanthroimidazole (PI) and various fluorene derivatives via benzene bridges. The crystallographic study confirms that only C–H⋯π weak intermolecular interactions exist in these crystals, which is conducive to obtaining high solid-state fluorescence efficiency, and eventually, the photoluminescence quantum yields (PLQYs) of PPI-2-DMF, PPI-2-DPF and PPI-3-SBF reach 57.56, 67.22 and 66.05%, respectively. PPI-3-SBF exhibits the shortest conjugation length among the three molecules, leading to the bluest emission. As a result, the non-doped device with PPI-3-SBF as an emitting layer realizes a high maximum EQE of 8.41% with CIE coordinates of (0.16, 0.07), accompanied by a relatively low efficiency roll-off. These findings would provide a new strategy of molecular structure design for highly efficient deep blue non-doped OLEDs.

Graphical abstract: Rational molecular design of phenanthroimidazole-based fluorescent materials towards high-efficiency non-doped deep blue OLEDs

Supplementary files

Article information

Article type
Paper
Submitted
04 Jun 2022
Accepted
13 Aug 2022
First published
15 Aug 2022

J. Mater. Chem. C, 2022,10, 14186-14193

Rational molecular design of phenanthroimidazole-based fluorescent materials towards high-efficiency non-doped deep blue OLEDs

C. Du, T. Lu, Z. Cheng, Y. Chang, H. Liu, J. Wang, L. Wan, Y. Lv and P. Lu, J. Mater. Chem. C, 2022, 10, 14186 DOI: 10.1039/D2TC02329F

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