ULTRAHIGH EFFICIENCY SOLAR CELL WITH TANDEM STRUCTURE

摘要

PURPOSE:To obtain a solar cell of ultrahigh efficiency by a method wherein a single crystal Si solar cell, a solar cell formed of a GaAs compound semiconductor thin film whose forbidden bandwidth is in a specific range of eV, and a solar cell formed of a GaAs compound semiconductor thin film possesses of a forbidden bandwidth which lies in another range of eV are stacked up in tandem. CONSTITUTION:An N-type Si layer 2 is formed on a P-type Si layer 1 to form a single crystal Si solar cell 7. A first solar cell 8 formed of a GaAsP compound semiconductor thin film whose forbidden bandwidth is 1.57-1.73eV and a second solar cell 9 formed of a GaAsP compound semiconductor thin film or a GaP compound semiconductor thin film whose forbidden bandwidth is 2.23-2.27eV are successively stacked up thereon in hetero junction in a tandem structure. The cell 9 is provided in such a manner that an electrode 11 of GaAs1-xPx is formed on the cell 8, and the cell 9 composed of a P-type GaAs1-xPx layer 5 and an N-type GaAs1-xPx layer 6 is provided thereon. An electrode 12 of P+-GaAsP is provided onto the cell 9 concerned, and a Ti2O5 layer is formed thereon as an antireflection film 13.