A NOVEL-APPROACH FOR PREPARING SINGLE-LAYER MOLECULARLY DOPED ELECTROLUMINESCENT POLYMER THIN-FILMS

A single-layer molecularly doped electroluminescent (OEL) polymer thin film has been prepared via a vapor codeposition process. The presente d method may be conveniently applied to many dye-doped polymer thin fi lm systems yet without having to go through existing complicated conve ntional synthesis and fabrication processes. This method, proven in th is work to be feasible experimentally, was executed by simultaneously codepositing an EL active dye, a hole-transporting molecule triphenyld iamine derivative (TPD), and two polyimide thin film forming monomers on an indium-tin oxide (ITO) substrate. Carrier injection was provided from an ITO anode and a thermally evaporated aluminum electrode. Elec tron-hole recombination and the green light in EL spectra, with an emi ssion maximum at 515 nn, were triggered at a driving voltage of 14 V. Two primary degradation behaviors were identified. First, hydrolysis o f the thin films led to the reduction in EL intensity. Second, nonunif orm structure formation of the top Al metal in the Al and codeposition film interface caused reduction in the active emission area and incre ased the driving voltage required.