Benzothiadiazole-Based Green Hybridized Local and Charge-Transfer (HLCT) Fluorophores as Solution-Processed Non-Doped Emitters for Simple Structured Electroluminescent Devices

Herein, two new solution-processable HLCT fluorophores (CBzF and CBzFC) based on benzothiadiazole (Bz) derivatives were designed and synthesized (HLCT=hybridized local and charge transfer). Their optical and photophysical properties were experimentally and theoretically studied and verified by the solvatochromic effect and density functional theory calculations. The two molecules demonstrate high solubility, HLCT features, and an intense green fluorescence with solid-state photoluminescence quantum yields of 63-72 %. Both fluorophores are effectively applied as non-doped emitters for solution-processed double-layered OLEDs, which produce intense green emission colors with low turn-on voltages (3.0-3.2 V). Specifically, the CBzFC-based solution-processed device achieves a high maximum luminescence (24400 cd m(-2)), high maximum efficiencies (EQE(max)=5.59 %, CEmax=12.24 cd A(-1), and PEmax=10.54 lm W-1), and decent efficiency low-off.