Based on triphenylamine-imidazole skeleton electrofluorochromic small organic molecules: Synthesis and electrofluorochromic properties

Five donor–acceptor (D-A) small organic molecule compounds were designed and synthesized by using triphenylamine (TPA) as the donor and imidazole as the acceptor. Through introducing different substituent groups at the para position of TPA, the excited state characteristics were adjusted, and a reversible and stable color change was obtained. These compounds exhibited good thermal properties. All five compounds were evaluated as small organic molecule materials for electrofluorochromism (EFC) and achieved luminescence conversion from blue to yellow at low voltages, and the compound 4e realized electroluminescence conversion at only 0.6 V due to the introduction of –OCH3. The stability of the EFC devices was demonstrated by the CV curves for 400 cycles. The color-changing voltages of EFC can be effectively reduced by adjusting the characteristics of ICT. This rational structural design of small organic molecules provides a new design strategy for the preparation of EFC materials.