One-step fabrication of organic nanoparticles as scattering media for extracting substrate waveguide light from organic light-emitting diodes

Tetraphenylethene (TPE) nanoparticles have been easily obtained by one-step vacuum sublimation the TPE powder. The TPE molecules crystallize themselves in room temperature which is probably due to their extremely low glass transition temperature. The as-deposited TPE nanoparticles scatter light effectively. By employing the TPE nanoparticles as scattering media for extracting the substrate waveguide light from blue organic light-emitting diodes (OLEDs), a 28% efficiency improvement has been obtained. By further co-evaporating the TPE and its derivative 4-(4-(1,2,2-triphenylvinyl) phenyl)-7-(5-(4-(1,2,2-triphenylvinyl)phenyl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole (BTPETTD) as a color conversion and light scattering layer for the blue OLEDs, the blue-to-white photon conversion efficiency of the resultant white OLEDs has been enhanced from 52.7% to 70.1%, representing a 33% improvement. The vacuum sublimed TPE nanoparticles can find a wide variety of applications in optoelectronic devices such as solar cells and LEDs.