LXXXVIII.<i>On certain variations in the optical constants of copper</i>

“…A major influence of a difference in reflectivity between Hg and Ca on the brightness of the devices can be excluded, since the reflectivity is even slightly smaller for Hg than for Ca. 37,38 The reason for the difference in the brightness is in the difference of the number of quenching sites in the devices. It has been shown that gap states act as quenching sites, and reduce the brightness of LEDs.…”

Section: B Ca and Ba Amalgam Electrodes Versus Evaporated Ca Cathodesmentioning

confidence: 99%

Liquid metals as electrodes in polymer light emitting diodes

Andersson

Gommans

Gon

et al. 2003

Journal of Applied Physics

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We demonstrate that liquid metals can be used as cathodes in light emitting diodes ͑pLEDs͒. The main difference between the use of liquid cathodes and evaporated cathodes is the sharpness of the metal-polymer interface. Liquid metal cathodes result in significantly sharper metal-organic interfaces than vapor deposited cathodes, due to the high surface energy of the metals. The sharper interface in pLEDs with liquid metal cathodes is observed by neutral impact collision ion scattering spectroscopy and low energy ion scattering spectroscopy measurements. The influence of interface sharpness on device performance was studied by comparing current-voltage-light characteristics of devices with OC 1 C 10 paraphenylenevinylene ͑PPV͒ as electroluminescent polymer and indium tin oxide ͑ITO͒ as hole injection electrode, and different cathodes. Comparison of devices using a liquid Ga cathode and an evaporated Al cathode showed that light emission for the liquid Ga cathode is two orders of magnitude larger than for the evaporated Al cathode, and that the external light efficiency is increased by an order of magnitude. Since the work function of Ga and Al is nearly the same, the poor performance for evaporated Al LEDs is attributed to the formation of an interfacial layer where Al has diffused into, and reacted with, the PPV. This interfacial layer has poor electrical conduction compared to pure PPV, and contains quenching sites which reduce light emission. Low work function liquid metal cathodes were studied by using liquid Ca and Ba amalgams. The improved performance of liquid amalgam pLEDs is attributed to the different structure of the metal-polymer interface. The enormous increase in light and current through the amalgam devices compared to those using pure Hg demonstrate that less than 1 ML of a metal with a low work function at the polymer-cathode interface can have a dramatic effect on the performance of the devices. Devices with a liquid Ca amalgam cathode showed an increase of the current ͑by 50%͒ and brightness ͑80%͒ compared to devices with an evaporated Ca cathode, which is ascribed to reduced diffusion of Ca into the emissive PPV layer.

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The bases of a scheme for identification of ore minerals by optical methods

Eales

1969

Mineral. Deposita

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LXXXVIII.On certain variations in the optical constants of copper

Cited by 10 publications

References 9 publications

LXII.An experimental investigation on the influence of the polished surface on the optical constants of copper as determined by the method of drude

LXII.An experimental investigation on the influence of the polished surface on the optical constants of copper as determined by the method of drude

Liquid metals as electrodes in polymer light emitting diodes

The bases of a scheme for identification of ore minerals by optical methods

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