A matrix, including epithelial basement membrane, for inducing repair of mammalian tissue defects and in vitro cell propagation derived from epithelial tissues of a warm-blooded vertebrate. The bifacial photovoltaic device comprises an electrically conductive core electrode, a plurality of semiconductor layers covering one end region of the core electrode and at least a portion of the two faces of the core electrode, a first counter electrode, a second counter electrode, and a third counter electrode connecting the first and the second counter electrodes. In order to provide a copper-alloy foil, which can attain improved tracking width, the following ratio of thermal expansion and shrinkage is adjusted in a range of from 0. Since the deposition of semiconductor materials, in particular AllnGaN, may lead to different emission wavelengths of the deposited material, the use of a thermal radiation absorption layer may produce a narrower emission wavelength distribution of the deposited material.