Optical Properties of Eu Doped CaF2 Crystal for Solar Cell Application

The high transparency CaF₂ crystals have been made by the vertical Bridgman technique under the vacuum condition. Since low surface tension of CaF₂ melt, crystal shape is controllable using mold crucible. We have been grown shaped crystals such as ribbon, triangle, and quadrilateral shaped crystals successfully and confirmed the grooves could be made on the crystal surface using this method. The Frenel lens was made using the crucible including many grooves inside. Eu doped CaF₂ crystals have been made and we confirmed that the crystal can effectively convert the UV light shorter than 400nm into 420nm. The Eu doped CaF₂ crystal has the property of very low transmittance loss with a function of down convention in UV region