First Solar, Inc.

According to the embodiments provided herein, a method for sputtering a TCO material onto a substrate includes process conditions that produce a textured topography at the interfaces of various layers. The textured topography can include an average roughness from about 5 to about 40 nm. The process conditions can include providing oxygen in the sputtering environment at a flow rate of from 0 to about 30 sccm; or heating the substrate to at least 200; or increasing the magnetic field strength to above 40 mT. The textured topography creates interfacial transition areas which have hybrid physical properties compared to their constituent materials.

Photovoltaic devices with type II-VI semiconductor absorber materials having improved carrier extraction layers are described herein. Methods of treating semiconductor absorber layers and forming improved carrier extraction layers and p-type contact layers are described.

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 CdSe x Te (1-x) , wherein x is from 1 to about 40 at. %. The transparent tunnel junction comprises a transparent interface layer of Cd y Zn (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.

A photovoltaic device is presented. The photovoltaic device includes a layer stack; and an absorber layer is disposed on the layer stack. The absorber layer comprises selenium, wherein an atomic concentration of selenium varies across a thickness of the absorber layer. The photovoltaic device is substantially free of a cadmium sulfide layer.

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.

A photovoltaic cell can include an interfacial layer in contact with a semiconductor layer.

According to the embodiments provided herein, a photovoltaic device can include a buffer layer adjacent to an absorber layer doped p-type with a group V dopant. The buffer layer can have a plurality of layers compatible with group V dopants.

According to the embodiments provided herein, a method for forming a photovoltaic device can include depositing a plurality of semiconductor layers. The plurality of semiconductor layers can include a doped layer that is doped with a group V dopant. The doped layer can include cadmium selenide or cadmium telluride. The method can include annealing the plurality of semiconductor layers to form an absorber layer.

The invention relates to a thin film solar module comprising a monolithic solar cell array, including a plurality of solar cells with a layer structure, comprising a rear contact layer, a front contact layer and an absorber layer between the rear contact layer and the front contact layer, and an electrical connection structure for electrically serially connecting neighboring solar cells. The invention also relates to an associated production method.