Spectral emissivity of ytterbium oxide-based materials for application as selective emitters in thermophotovoltaic devices

The spectral emissivity of Yb3+ in a series of compounds has been investiga ted to study the effects of crystal structure type, chemical environment, y tterbium concentration, impurity concentration and temperature on the spect ral radiant intensity of the selective emitter peak and emitted power from the material. A figure of merit has been defined which enables the compound s to be ranked for application in a practical thermophotovoltaic energy con version device. It is shown that significant selective emission can be achi eved from compounds in which the Yb3+ concentration is as low as 10 mol%. A part from pure Yb2O3, the compounds Yb3Al5O12, YbNbO4 and Y0.9Yb0.1O1.5 are found to have emission spectra suitable for efficient matching to silicon photovoltaic cells. (C) 1999 Elsevier Science B.V. All rights reserved.