The invention refers to a method for activating an absorber layer of a semi-finished thin-film solar cell. The absorber layer comprises CdSe.sub.xTe.sub.1-x, CdSe, CdS or CdTe. The method comprises the steps of providing a semi-finished thin-film solar cell with an absorber layer comprising a CdSe.sub.xTe.sub.1-x, layer or comprising at least two layers selected from CdS, CdTe, ZnTe, CdSe, forming a polyvinylchloride film on a surface of the absorber layer, and performing a heat treatment of the semi-finished thin-film solar cell with the polyvinylchloride film on it, wherein the temperature is in the range of 300 C. to 500 C.

A photovoltaic device includes a substrate, a semiconductor stack and a transparent tunnel junction. The semiconductor stack includes an n-type layer selected from a first transparent conductive oxide layer, or a window layer, or both; and a p-type absorber layer disposed on the n-type layer, wherein the absorber layer consists essentially of CdSexTe(1-x), wherein x is from 1 to about 40 at. %. The transparent tunnel junction comprises a transparent interface layer of Cd.sub.yZn.sub.(1-y)Te doped to be p+type, and a transparent contact layer doped to be n+type, and the interface layer is disposed between the p-type absorber layer and the transparent contact layer. In bifacial embodiments, the tunnel junction forms a transparent back contact and electrode; and in multi-junction embodiments, the tunnel junction forms a diode-like connector between top and bottom cells. The transparent contact layer may comprise tin oxide or zinc oxide doped with aluminum, fluorine or indium. The photovoltaic device may also include an electron reflector layer and/or an optical reflector layer.

A photovoltaic device includes a substrate, a semiconductor stack and a transparent tunnel junction. The semiconductor stack includes an n-type layer selected from a first transparent conductive oxide layer, or a window layer, or both; and a p-type absorber layer disposed on the n-type layer, wherein the absorber layer consists essentially of CdSexTe(1-x), wherein x is from 1 to about 40 at. %. The transparent tunnel junction comprises a transparent interface layer of Cd.sub.yZn.sub.(1-y)Te doped to be p+type, and a transparent contact layer doped to be n+type, and the interface layer is disposed between the p-type absorber layer and the transparent contact layer. In bifacial embodiments, the tunnel junction forms a transparent back contact and electrode; and in multi-junction embodiments, the tunnel junction forms a diode-like connector between top and bottom cells. The transparent contact layer may comprise tin oxide or zinc oxide doped with aluminum, fluorine or indium. The photovoltaic device may also include an electron reflector layer and/or an optical reflector layer.

A photovoltaic device includes a substrate structure and a p-type semiconductor absorber layer, the substrate structure including a CdSSe layer. A photovoltaic device may alternatively include a CdSeTe layer. A process for manufacturing a photovoltaic device includes forming a CdSSe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process includes forming a p-type absorber layer above the CdSSe layer.

A method for forming a thin film having sulfide single-crystal nanoparticles includes dropping a sulfide precursor solution on the surface of a Group VI absorption layer, and then performing thermal decomposition on the sulfide precursor solution under a predetermined temperature to form a thin film consisting of sulfide single-crystal nanoparticles on the surface of the Group VI absorption layer.

A photovoltaic device includes a substrate structure and a p-type semiconductor absorber layer, the substrate structure including a CdSSe layer. A photovoltaic device may alternatively include a CdSeTe layer. A process for manufacturing a photovoltaic device includes forming a CdSSe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process includes forming a p-type absorber layer above the CdSSe layer.

A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

Disclosed are methods for the surface cleaning and passivation of PV absorbers, such as CdTe substrates usable in solar cells, and devices made by such methods. In some embodiments, the method involves an anode layer ion source (ALIS) plasma discharge process to clean and oxidize a CdTe surface to produce a thin oxide layer between the CdTe layer and subsequent back contact layer(s).

Embodiments of a photovoltaic device are provided herein. The photovoltaic device can include a layer stack and an absorber layer disposed on the layer stack. The absorber layer can include a first region and a second region. Each of the first region of the absorber layer and the second region of the absorber layer can include a compound comprising cadmium, selenium, and tellurium. An atomic concentration of selenium can vary across the absorber layer. The first region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. The second region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. A ratio of an average atomic concentration of selenium in the first region of the absorber layer to an average atomic concentration of selenium in the second region of the absorber layer can be greater than 10.

Embodiments of a photovoltaic device are provided herein. The photovoltaic device can include a layer stack and an absorber layer disposed on the layer stack. The absorber layer can include a first region and a second region. Each of the first region of the absorber layer and the second region of the absorber layer can include a compound comprising cadmium, selenium, and tellurium. An atomic concentration of selenium can vary across the absorber layer. The first region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. The second region of the absorber layer can have a thickness between 100 nanometers to 3000 nanometers. A ratio of an average atomic concentration of selenium in the first region of the absorber layer to an average atomic concentration of selenium in the second region of the absorber layer can be greater than 10.