Mitchell Stewart Burberry

19.2: Color Filter Formulations for Full-Color OLED Displays: High Color Gamut Plus Improved Efficiency and Lifetime

This paper describes Eastman Kodak Companys new color filter formulations for use in White OLED displays. The new filters deliver a substantially higher color gamut compared with commercially available LCD filters at nominal thickness, and substantially higher efficiency and lifetimes, when compared with thickened versions of the same LCD filters..

Passivation of ZnO TFTs

— The impact of passivation processes on ZnO thin-film transistors is reported. In general, passivation processes result in back-channel doping, which corresponds to shifts in threshold voltage and changes in subthreshold slope. It was determined that ALD-based passivation results in considerably smaller undesirable shifts than those observed with plasma-based processes. Two approaches, one a bulk doping with ammonia and the other a surface treatment with hydrogen peroxide, to further mitigate the detrimental effects of the passivation process are described. After proper passivation, ZnO devices show negligible hysteresis, have excellent stability to bias stress, and maintain or improve the good transport properties of as-deposited devices. Although the existence of grain boundaries has been assumed to be a point of concern for device stability in polycrystalline metal oxides, no evidence was found to suggest that the grain boundaries present in these ZnO thin-film transistors have affected the device stability.

Cycle time effects on growth and transistor characteristics of spatial atomic layer deposition of zinc oxide

The authors have investigated the effects on growth and on electrical characteristics of varying the cycle time for atomic layer deposited zinc oxide films. The samples are grown at atmospheric pressure. By using a spatial atomic layer deposition head, we can access both pulse and purge times as short as 0.025 s, which appears to be a regime that yields useful material properties. Shorter purge times allow higher growth rates at 200 °C and are correlated with both higher resistivity, better transistor gating, and higher thin-film-transistor mobility. The authors clarify that when comparing results, the purge time must be taken into account.

Uniform ZnO Thin-Film Transistors by an Ambient Process

We have fabricated zinc oxide thin-film transistors using a novel ambient deposition process, with maximum temperature of 200degC. The TFTs deposited this way show sufficiently good properties to make them potentially applicable to OLED display backplanes.

Multiple localized exciton species in sulfied-doped AgBr detected by luminescence and ODMR

Abstract The low temperature photoluminescence of sulfide-doped AgBr has been examined with both steady state and pulsed excitation. Emission bands peaking at about 495, 566, 596, and 725 nm are observed, depending upon excitation conditions. Subband-gap excitation resonances at 464, 496, 530, and 558 nm are observed, depending upon monitoring wavelength. Excitation at 496 nm preferentially enhances 596 nm emission, which gives rise to an ODMR spectrum. ODMR data indicate that at least three species are contributing to the 596 nm emission. These species are interpreted as triplet excitons. A highly antisotropic species observed in the ODMR spectra is interpreted as a triplet exciton bound to a substitutional divalent sulfur ion/interstitial silver ion complex with approximate [111] symmetry.

Characterization of an intermediate case exciton in the emission of Cd-doped and pure AgBr

Abstract Pulsed emission data and ODMR spectra of the 580 nm band provide evidence for an intermediate case exciton in pure and Cd2+-doped AgBr. This interpretation is based on the observed g-factor and the absence of a wavelength shift of the emission after pulsed excitation in pure AgBr. It is supported by the response of the ODMR spectra as the microwave modulation frequency is changed. The two central ODMR lines observed in AgBr (g = 1. 78) are assigned to transitions from the ms=±1 levels to the ms = 0 level of an intermediate case triplet exciton, which has an exchange coupling (singlet-triplet splitting) of -1. 9 ± 0. 2 cm−1.