High efficiency selenium heterojunction solar cells

Abstract

A photocell includes a metallic base electrode, a continuous, crystalline P-type semiconductive selenium layer less than about 50 microns thick, a thin tellurium layer interposed therebetween to metallurgically bond the base electrode to the selenium layer and to form an ohmic contact between the base electrode and the selenium layer, a thin N-type semiconductive cadmium selenide layer contiguous with the selenium layer and forming a photovoltaic heterojunction therebetween, a pellucid layer of at least one cadmium chalcogenide contiguous with the cadmium selenide layer and forming an ohmic contact therewith and a current collecting electrode on the cadmium chalcogenide layer. The sunlight conversion efficiency of the cell is at least about 3.0%. The efficiency can be further improved by doping the selenium layer to improve its conductivity and by providing an N-type layer of cadmium selenide and N.sup.+ cadmium oxide. This can be done by continuously varying the oxygen content of the N-type layer. It is further helpful if a counterelectrode in the form of a grid is added, which minimizes both the resistance between the grid members in the cadmium layer and the blockage of light by the grid.

Dependencies are inferred from the claim text.