Improved planar solar converter based on uranyl neodymium and holmium glasses

Abstract

The use of uranyl doped glasses for solar energy conversion and concentration was discussed by Reisfeld and Neuman¹. While the UO²⁺₂ ion is an efficient energy converter, its maximum emission peaking around 500 nm does not coincide with the maximum sensitivity of the existing solar cells which is around 700–1,000 nm. The use of Nd³⁺ doped glasses for solar energy collectors was described by Levitt and Weber². While the emission of Nd³⁺ peaking at 880 nm (⁴F_3/2→⁴I_9/2) and at 1.06 µm (⁴F_3/2→⁴I_11/2) is ideal for matching with the maximum sensitivity of solar cells, its absorbance arising from the forbidden transition 4f–4f is low and the overlap of the absorption spectrum of Nd³⁺ with the solar spectrum is rather weak. To increase the operational efficiency of solar collectors, a maximum overlap between the absorption spectrum of the collector and the solar spectrum is required³. In this report we suggest that glasses doped by uranyl and neodymium and uranyl and holmium increase the response to the solar spectrum, thus increasing the collection efficiency, and convert the absorbed light in the wide spectral range into the narrow fluorescence band at 1.06 µm and 880 nm in uranyl–neodymium glasses and 660 nm (⁵F₅→⁵I₈) and 750 nm (⁵F₄, ⁵S₂→⁵I₇) in the uranyl-holmium co-doped glasses.