No abstract

We present data on the deposition of various organic materials using Organic Vapor Phase Deposition (OVPD®) for use in efficient red OLEDs. The long term stability of the OVPD process has been investigated, showing reproducibility of deposition rates to be better than ± 1.5% for a period of up to 30 days. Due to the highly reproducible process the knowledge of the sublimation behaviour of organic materials allows precise determination of OVPD process parameters from single calibration curves as well as process transfer from R&D and Pilot Production equipment to Production equipment. A red phosphorescent OLED employing Iridium(III)bis(2‐(2′‐benzothienyl)pyridinato‐N,C3′)(acetylacetonate)(Btp2Ir(acac)) was fabricated with OVPD yielding high efficiencies.

We investigated the effect of thermal stress, caused by the deposition of aluminum on top of an organic light emitting diode (OLED), on the device performance and proved our simulated results by experimental tests. Concerning the temperature of the substrate, we found a much larger influence of thermal radiation, caused by the evaporation source and the environmental setting compared to the kinetic and thermal energy of the deposited material itself. Due to these results, we developed a new system for metal deposition, using the flash-evaporation technique. Using it, we were able to minimize the influence of thermal radiation and geometry on the evaporation. Therefore the substrate heating was reduced by more than 90 % and the photometric efficiencies of test-devices were improved slightly. Additionally the time of deposition and retention was lowered by 90 %, with an increased material yield of more than 55 % at the same time. The resistance of the conducting layer decreases by two orders of magnitude, caused by emerging micro crystals. Surprisingly, the roughness of the surface actually decreased slightly.