A method of forming a Group II-VI multijunction semiconductor device comprises providing a Group IV substrate, forming a first subcell from a first Group II-VI semiconductor material, forming a second subcell from a second Group II-VI semiconductor material, and removing the substrate. The first subcell is formed over the substrate and has a first bandgap, while the second subcell is formed over the first subcell and has a second bandgap which is smaller than the first bandgap. Additional subcells may be formed over the second subcell with the bandgap of each subcell smaller than that of the preceding subcell and with each subcell preferably separated from the preceding subcell by a tunnel junction. Prior to the removal of the substrate, a support layer is affixed to the last-formed subcell in opposition to the substrate.

Disclosed are ultrathin layers of group II-VI semiconductors, group II-VI semiconductor superlattice structures, photovoltaic devices incorporating the layers and superlattice structures and related methods. The superlattice structures comprise an ultrathin layer of a first group II-VI semiconductor alternating with an ultrathin layer of at least one additional semiconductor, e.g., a second group II-VI semiconductor, or a group IV semiconductor, or a group III-V semiconductor.

Disclosed are ultrathin layers of group II-VI semiconductors, group II-VI semiconductor superlattice structures, photovoltaic devices incorporating the layers and superlattice structures and related methods. The superlattice structures comprise an ultrathin layer of a first group II-VI semiconductor alternating with an ultrathin layer of at least one additional semiconductor, e.g., a second group II-VI semiconductor, or a group IV semiconductor, or a group III-V semiconductor.

The present invention proposes a method to form a gradient thin film using a spray pyrolysis technique. The method comprises providing a base substrate, preparing a spray aqueous solution by mixing at least two precursor compounds comprising at least two different elements and spraying the spray aqueous solution onto the base substrate. According to the present invention, the ratio of the concentration of the at least two different elements within the spray aqueous solution is varied while performing the method. In this way, a thin film having a gradient of elemental composition over its layer thickness may be formed.

The present invention proposes a method to form a gradient thin film using a spray pyrolysis technique. The method comprises providing a base substrate, preparing a spray aqueous solution by mixing at least two precursor compounds comprising at least two different elements and spraying the spray aqueous solution onto the base substrate. According to the present invention, the ratio of the concentration of the at least two different elements within the spray aqueous solution is varied while performing the method. In this way, a thin film having a gradient of elemental composition over its layer thickness may be formed.

A photovoltaic device is disclosed including at least one Cadmium Sulfide Telluride (CdS.sub.xTe.sub.1−x) layer as are methods of forming such a photovoltaic device.

A photovoltaic device is disclosed including at least one Cadmium Sulfide Telluride (CdS.sub.xTe.sub.1−x) layer as are methods of forming such a photovoltaic device.

Described herein is a diffusion-based ex-situ group V element doping method in the CdCl.sub.2 heat-treated polycrystalline CdTe film. The ex-situ doping using group V halides, such as PCl.sub.3, AsCl.sub.3, SbCl.sub.3, or BiCl.sub.3, demonstrated a promising PCE of ˜18% and long-term light soaking stability in CdSe/CdTe and CdS/CdTe devices with decent carrier concentration>10.sup.15 cm.sup.−3. This ex-situ solution or vapor process can provide a low-cost alternative pathway for effective doping of As, as well as P, Sb, and Bi, in CdTe solar cells with limited deviation from the current CdTe manufacturing process.

Methods and devices are described for a photovoltaic device. The photovoltaic device includes a glass substrate, a semiconductor absorber layer formed over the glass substrate, a metal back contact layer formed over the semiconductor absorber layer, and a p-type back contact buffer layer formed from one of MnTe, Cd.sub.1-xMn.sub.xTe, and SnTe, the buffer layer disposed between the semiconductor absorber layer and the metal back contact layer.

Methods and devices are described for a photovoltaic device. The photovoltaic device includes a glass substrate, a semiconductor absorber layer formed over the glass substrate, a metal back contact layer formed over the semiconductor absorber layer, and a p-type back contact buffer layer formed from one of MnTe, Cd.sub.1-xMn.sub.xTe, and SnTe, the buffer layer disposed between the semiconductor absorber layer and the metal back contact layer.