Efficient narrow-band red-light-emitting diodes based on ambipolar organic single crystals

Organic single crystals have attracted immense attention in the field of organic light-emitting devices (OLEDs), owing to their unique advantages of long-range molecular ordering, high carrier mobility, high fluorescent quantum yield and low impurity content. Development of high-performance organic single crystal-based OLEDs with narrow-band emission is critical for high-purity displaying, yet it is still a major challenge to obtain a crystal-based OLED with both narrow fullwidth at half maximum (FWHM) and high electroluminescence (EL) performance. Here, molecular doping engineering is employed by taking 2,6-diphenylanthracene (DPA) as host crystal and pentacene (Pen) as red guest emitter material. 2,2 '-Bis[4-(trifluoromethyl)phenyl]-5,5 '-bithiazole (BTPB) with strong electron-withdrawing ability are further doped for the growth of ambipolar crystals in order for balanced hole and electron mobility. As a result, DPA: 3% Pen: 15% BTPB crystal-based OLEDs exhibit a maximum luminance and current efficiency of 10,850 cd m(-2) and 1.91 cd A(-1), respectively, and an EQE of 1.51%. The obtained red-light-emission with a narrow FWHM increases high color purity of crystal-based OLEDs. It demonstrates that high-performance crystal-based OLEDs with narrow-band emission are of great significance for the development of organic electronics, especially for display and lighting applications.