Synthesis, crystal structure, aggregation-induced emission (AIE) and electroluminescence properties of a novel emitting material based on pyrrolo[3,2-b]pyrrole

Abstract

A novel electroluminescent (EL) material based on a pyrrolo[3,2-b]pyrrole skeleton as a donor group and dimesitylborane as an acceptor group, 1,4-bis(4-(dimethylboryl) phenyl)-2,5-diphenyl-1,4-dihydropyrrolo[3,2-b]pyrrole (DMBPDPP), has been successfully synthesized and fully characterized by elemental analysis, mass spectrometry, NMR spectroscopy and X-ray crystallography. Furthermore, the thermal stability and the electrochemical as well as photophysical properties including aggregation-induced emission (AIE) behaviors were systematically investigated not only by experimental methods but also by theoretical calculations. Herein, we found that the compound exhibits high thermal stability, electrochemical stability and significant AIE behaviors. X-ray crystal analysis assisted with DFT calculation provides insights into the origin of the luminescence properties and AIE characteristics. In addition, a non-doped OLED (device A) and doped OLEDs (device B, device C and device D) were fabricated with DMBPDPP and DMBPDPP in the CBP host as light-emitting layers, respectively. Among these OLEDs, the non-doped OLED (device A) shows excellent EL efficiencies of 4158 cd m⁻², 5.95 cd A⁻¹, 5.30 lm W⁻¹ and 2.04%. The doped OLED (device C) with 5 wt% DMBPDPP in CBP shows better maximum brightness, maximum current efficiency, maximum power efficiency and external quantum efficiency of 13 500 cd m⁻², 8.64 cd A⁻¹, 8.44 lm W⁻¹ and 2.83%, respectively. The electroluminescent properties of the compound demonstrate that DMBPDPP is a potential candidate for fabricating electroluminescent devices.