ELECTROLUMINESCENT BEHAVIORS IN MULTILAYER THIN-FILM ELECTROLUMINESCENT DEVICES USING 9,10-BISSTYRYLANTHRACENE DERIVATIVES

Using nine 9,10-bisstyrylanthracene derivatives (BSA's) with different substituents as emission layer materials, multilayer electroluminescent (EL) devices were fabricated. Among nine BSA's, three BSA's were found to exhibit high EL performance. Four types of devices, a single-layer device with a BSA emission layer, two types of two-layer devices in which BSA emission layers were combined with a triphenylamine dimer as a hole transport layer or an oxadiazole derivative as an electron transport layer, and a three-layer device, were fabricated using the three BSA's. The relationships between the device structures and EL performances of these devices were studied. Ionization potential values in vacuum-deposited films of BSA's were measured. It was found that the introduction of an electron withdrawing group increased electron injection/transport capability, and that of electron donating groups increased hole injection/transport capability. The relative EL efficiencies of various devices were discussed in terms of the electronic nature of BSA's.