Electroluminescent polyhedral oligomeric silsesquioxane-based nanoparticle

A polyhedral oligomeric silsesquioxane (POSS)-based blue light electroluminescent nanoparticle, POSS-FL3, which contains a terfluorene chromophore on each of its eight arms, was easily prepared via the hydrosilation reaction between octakis(dimethylsiloxy) silsesquioxane and an allyl-functionalized terfluorene chromophore that emits blue light as a result of photo- or electroexcitation. POSS-FL3 exhibits good solubility in common organic solvents, such as chloroform, THF, toluene, p-xylene, and chlorobenzene, and good film-forming properties on a quartz plate or an indium tin oxide (ITO) plate; i.e., it has good solution processing properties. The good spectral overlap of the maximum absorption wavelength ( 391 nm in THF solution) of poly( dihexylfluorene) with the maximum emission wavelengths ( 394 nm in THF solution) of POSS-FL3 suggests that POSS-FL3 can be used as a dopant of blue light-emissive conjugated polymers such as polyfluorenes to increase their quantum efficiencies through energy transfer. A single-layered electroluminescence (EL) device with the configuration of ITO/PEDOT: PSS/POSS-FL3/Ca ( 500 nm)/Al ( 800 nm) was fabricated, with maximum EL peaks at 400, 422, and 464 nm. The external quantum efficiency (EQE) of the POSS-FL3 device ( 0.0164%) was found to be higher than that of poly( dihexylfluorene) devices in EL devices (0.0095%). Surprisingly, the external quantum efficiencies in EL devices of POSS-FL3 doped poly( dihexylfluorene) blends were found to be about 4-8 times greater than that of poly( dihexylfluorene).