Photovoltaic cell and method of making same

Claim 1

A photovoltaic cell having a first electrically conductive contact, a first semiconductor layer, a second semiconductor layer of opposite type of conductivity, and a second electrically conductive contact, arranged in the stated order in layers one above the other, and a further layer capable of being tunnelled through by electrons and holes, said further layer being arranged between one of the semiconductor layers and the nearest electrically conductive contact, characterized in that the further layer is a semiconductor inversion layer not permeable to ions, that the inversion layer is formed on the said one semiconductor layer, and that a low-resistivity layer that conducts electrons or holes well is arranged between the semiconductor inversion layer and the said nearest electrically conductive contact.

Claim 8

A method for manufacture of a Cu 2-x S/CdS thin film photovoltaic solar cell, comprising the sequential process steps (a) formation of the CdS layer on a first electrically conductive rear contact, (b1) formation of the Cu 2-x S layer on the CdS layer by vacuum deposition or sputtering of copper sulphide or immersion of the cadmium sulphide layer into a hot aqueous copper (I) chloride solution, (c) formation of an electrically conductive front contact and if necessary encapsulation of the solar cell, characterized by the further process steps following (b1) (b2) reduction in a hydrogen atmosphere glow discharge of Cu 2-z O with 0≦z≦1 present on the Cu 2-x S layer and of excess sulphur ions from the Cu 2-x S layer until a highly stoichiometric Cu 2 .0000 S layer is obtained, (b3) formation of a semiconductor inversion layer on and from the highly stoichiometric Cu 2 .0000 S layer by adsorption of H - ions from the hydrogen atmosphere of the glow discharge, (b4) reduction of the free surface of the inversion layer to elementary copper or application of elementary copper to the inversion layer, (b5) oxidation of elementary copper to Cu 2-y O with 0≦y≦1.

Claim 9

A method for manufacture of a Cu 2-x S/CdS thin film photovoltaic solar cell, comprising the sequential process steps (a) formation of the CdS layer on a first electrically conductive rear contact, (b1) formation of the Cu 2-x S layer on the CdS layer by vacuum deposition or sputtering of copper sulphide or immersion of the cadmium sulphide layer into a hot aqueous copper (I) chloride solution, (c) formation of an electrically conductive front contact and if necessary encapsulation of the solar cell, characterized by the further process steps following (b1) (b2) reduction in a hydrogen atmosphere glow discharge of Cu 2-z O with 0≦z≦1 present on the Cu 2-x S layer and of excess sulphur ions from the Cu 2-x S layer until a highly stoichiometric Cu 2 .0000 S layer is obtained, (b3) formation of a semiconductor inversion layer on and from the highly stoichiometric Cu 2 .0000 S layer by adsorption of H - ions from the hydrogen atmosphere of the glow discharge, (b4) reduction of the free surface of the inversion layer to elementary copper or application of elementary copper to the inversion layer, (b5) oxidation of elementary copper to Cu 2-y O with 0≦y≦1.