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 device includes a substrate structure and at least one Se-containing layer, such as a CdSeTe layer. A process for manufacturing the photovoltaic device includes forming the CdSeTe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process can also include controlling a thickness range of the Se-containing layer.

A photovoltaic device includes a substrate structure and at least one Se-containing layer, such as a CdSeTe layer. A process for manufacturing the photovoltaic device includes forming the CdSeTe layer over a substrate by at least one of sputtering, evaporation deposition, CVD, chemical bath deposition process, and vapor transport deposition process. The process can also include controlling a thickness range of the Se-containing layer.

The present invention proposes a method to form a CdSeTe thin film with a defined amount of selenium and with a high quality. The method comprises the steps of providing a base substrate and of depositing a partial CdSeTe layer on a first portion of the base substrate. The step of depositing a partial CdSeTe layer is performed at least twice, wherein a predetermined time period without deposition of a partial CdSeTe layer on the first portion of the base substrate is provided between two subsequent steps of depositing a partial CdSeTe layer. The temperature of the base substrate and the CdSeTe layer already deposited on the first portion of the base substrate is controlled during the predetermined time period such that re-evaporation of Cd and/or Te from the CdSeTe layer already deposited takes place.

Systems and methods of three-terminal tandem solar cells are described. Three-terminal metal electrodes can be formed to contact subcells of the tandem solar cell. The three-terminal tandem cell can improve the device efficiency to at least 30%.

Systems and methods of three-terminal tandem solar cells are described. Three-terminal metal electrodes can be formed to contact subcells of the tandem solar cell. The three-terminal tandem cell can improve the device efficiency to at least 30%.

A doped photovoltaic device is presented. The photovoltaic device includes a semiconductor absorber layer or stack disposed between a front contact and a back contact. The absorber layer comprises cadmium, selenium, and tellurium doped with Ag, and optionally with Cu. The Ag dopant may be added to the absorber in amounts ranging from 5×10.sup.15/cm.sup.3 to 2.5×10.sup.17/cm.sup.3 via any of several methods of application before, during, or after deposition of the absorber layer. The photovoltaic device has improved Fill Factor and P.sub.MAX at higher P.sub.r(=I.sub.sc*V.sub.oc product) values, e.g. about 160 W, which results in improved conversion efficiency compared to a device not doped with Ag. Improved PT may result from increased I.sub.sc, increased V.sub.oc, or both.

A doped photovoltaic device is presented. The photovoltaic device includes a semiconductor absorber layer or stack disposed between a front contact and a back contact. The absorber layer comprises cadmium, selenium, and tellurium doped with Ag, and optionally with Cu. The Ag dopant may be added to the absorber in amounts ranging from 5×10.sup.15/cm.sup.3 to 2.5×10.sup.17/cm.sup.3 via any of several methods of application before, during, or after deposition of the absorber layer. The photovoltaic device has improved Fill Factor and P.sub.MAX at higher P.sub.r(=I.sub.sc*V.sub.oc product) values, e.g. about 160 W, which results in improved conversion efficiency compared to a device not doped with Ag. Improved PT may result from increased I.sub.sc, increased V.sub.oc, or both.

Disclosed herein are compositions and methods for making polycrystalline thin films having very large grains sizes and exhibiting improved properties over existing thin films.

A photovoltaic device is presented. The photovoltaic device includes a buffer layer disposed on a transparent conductive oxide layer; a window layer disposed on the buffer layer; and an interlayer interposed between the transparent conductive oxide layer and the window layer. The interlayer includes a metal species, wherein the metal species includes gadolinium, beryllium, calcium, barium, strontium, scandium, yttrium, hafnium, cerium, lutetium, lanthanum, or combinations thereof. A method of making a photovoltaic device is also presented.