Tommie L. Royster

Highly efficient fluorescent-phosphorescent triplet-harvesting hybrid organic light-emitting diodes

We demonstrate highly efficient white and nonwhite hybrid organic light-emitting diodes (OLEDs) in which singlet and triplet excited states, generated in the recombination zone, are utilized by fluorescence and phosphorescence, respectively. The excited states are formed at a blue fluorescent light-emitting layer (LEL), and the triplets diffuse through a spacer layer to one or more phosphorescent LEL(s). A key feature enabling the triplet diffusion in such OLEDs is the use of a blue fluorescent emitter with triplet energy above, or not much below, that of the fluorescent host. Additional material properties required for triplet harvesting are outlined. At 1000 cd/m2 a blue and yellow harvesting OLED shows 13.6% external quantum efficiency, 3.8 V, 30.1 lm/W, and color characteristics suitable for display application. High-efficiency harvesting R+G+B white, and B+G and B+R nonwhite OLEDs are also demonstrated. The triplet-harvesting mechanism was verified in all devices by physical methods including spectra...

Fabrication and evaluation of thin-film solid-state sensors for hydrogen sulfide detection

Abstract Thin-film tungsten oxide sensors were fabricated by using metal-organic deposition (MOD) processes. Suitable tungsten carboxylate compounds were synthesized and used as precursor materials for the thin-films of tungsten oxide. The sensors were incorporated into a vacuum line as a new method of evaluation. Operation of the sensors under these conditions proved to be a useful way of providing a very sensitive, reproducible and stable system for measurement of low-level hydrogen sulfide evolved from aqueous solutions.

17.3: Highly Efficient Fluorescent/Phosphorescent OLED Devices Using Triplet Harvesting

We demonstrate efficient white and non-white hybrid OLED devices operating by a triplet harvesting mechanism to create light. Triplet excited states are generated in a blue fluorescent light-emitting layer (LEL) and utilized upon their diffusion to the phosphorescent LEL(s). At 1000 cd/m2 a blue/yellow hybrid OLED device shows external quantum efficiency (EQE) of 13.6%, 3.8 V, 30.1 lm/W, and excellent color characteristics suitable for display application. Performance of non-white-emitting hybrids, RGB white, and a tandem hybrid device is discussed. The triplet harvesting mechanism in all hybrid devices was verified by several experimental methods (spectral analysis, time-resolved electroluminescence (EL), magnetic field effect on EL).

30.4: Deep‐Blue OLEDs with Exceptional Device Lifetime

A novel class of group 13 electron-transporting materials and a strategic device architectural approach were used to advance the power efficiency and lifetime of deep-blue OLED devices. The advanced efficiency and exceptional device lifetime of these devices were enabled by material advancements. These advancements shed light on a possible mechanism linked to improved device lifetime.

5.2: Performance of Highly Efficient Electron Transporting Materials in OLED Displays

In this paper, we describe a new class of highly efficient electron-transporting materials evaluated using basic and advanced organic light-emitting diode (OLED) device structures. Data collected showed that the new class of materials provides higher device efficiency with lower operating drive voltage resulting in lower power-consuming devices. Competitive device lifetimes were also observed with some device structures showing significant improvements for the new materials. The data presented in this paper show that the advancements in efficiency and drive voltage can be realized in blue and red devices.