Fluorescent window for liquid junction solar cells

Abstract

To recover part of the often substantial fraction of the sunlight lost in practical semiconductor-liquid junction solar cells by solution absorption, two designs incorporating fluorescent windows are analyzed and tested. In these schemes the luminescers absorb incident light in regions of electrolyte absorption and re-emit at wavelengths both within the semiconductor band gap and the transparent range of the solution. It is shown that complete separation of the absorption and emission spectra (large Stokes shift) is essential for useful collection of these normally lost quanta. This requirement is not met by most fluorescent dyes, including the many with high quantum efficiency used in dye lasers. It is fulfilled by a europium(III) tetrakis diketonate which was successfully applied in the window of a n-CdSe/Na2S-S-Se-NaOH/C cell. A more efficient realization employs two solar cells, one edge-mounted on the fluorescent window to utilize the absorbed light, while the second operates in the conventional mode with light transmitted through the window. © 1980.