Up-conversion equivalent circuit to boost current in Si cells

Abstract

Up-conversion for Si solar cells using Er phosphors has the twin problems of a very high concentration requirement and the very narrow bandwidth for absorption. An alternative is to use the equivalent circuit of an up-converter, two below bnadgap solar cells connected in series to pump an above band gap LED, as suggested by Trupke SOLMAT 2005, but not yet attempted experimentally. Results on the current enhancement in such devices are shown for absorption of below Si band gap light in long wavelength cells to pump a InGaAs LED so as to sensitise a Si solar cell.