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Cosensitizer Phosphor System

IP.com Disclosure Number: IPCOM000077898D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Halpin, AT: AUTHOR [+2]

Abstract

A cosensitizer system is a phosphor host material containing three different rare earth metal ions. One is a primary sensitizer, e.g. Nd/3+/ which converts an external photon with a specific wavelength, e.g. 8100 Angstroms, into a form of nonradiative energy and transfers it to the secondary sensitizer. The secondary sensitizer, e.g Yb/3+/ in turn transfers the converted energy to the activator, e.g. Er/3+/. As a result, visible light is emitted by the activator. In addition, the second sensitizer converts an external photon of a different wavelength and transfers the resultant nonradiative energy to the activator. This also results in visible emission from the activator.

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Cosensitizer Phosphor System

A cosensitizer system is a phosphor host material containing three different rare earth metal ions. One is a primary sensitizer, e.g. Nd/3+/ which converts an external photon with a specific wavelength, e.g. 8100 Angstroms, into a form of nonradiative energy and transfers it to the secondary sensitizer. The secondary sensitizer, e.g Yb/3+/ in turn transfers the converted energy to the activator, e.g. Er/3+/. As a result, visible light is emitted by the activator. In addition, the second sensitizer converts an external photon of a different wavelength and transfers the resultant nonradiative energy to the activator. This also results in visible emission from the activator.

Accordingly, the activator Er/3+/, or alternatively Tm/3+/,is capable of receiving double-energy inputs and the overall efficiency of the system will be approximately equal or better than a single-sensitizer system, i.e., Yb/3+/:Er/3+/. In a typical application, the cosensitizer phosphor system is applied as a coating to GaAlAs and GaAsP light-emitting diodes (LED's) and responds to their respective wavelengths 8700 Angstroms and 7900 Angstroms.

A typical composition of the phosphor system is as follows: Yttrium Oxide
(69) Y(2)0(3) 160 gm Ytterbium Oxide (59) Yb(2)O(3) 34 gm Neodymium Oxide
(59) Nd(2)O(3) 8 gm Erbium Oxide (59) Er(2)O(3) 3.4 gm.

The above oxides are dissolved in concentrated HCl, diluted and washed by deionized water. Then they are coprecipitated and...