Disclosed is a solar cell including a substrate, an electrode layer disposed on the substrate, a p-type light-absorption layer disposed on the electrode layer, an n-type ZnS layer disposed on the p-type light-absorption layer, and a transparent electrode layer disposed on the n-type ZnS layer. The substrate can be immersed into an acidic solution of zinc salt, chelate, and thioacetamide, thereby forming the n-type ZnS layer on the substrate.

A method of forming a solar cell structure is provided, which includes forming a metal electrode on a substrate, forming an absorber layer on the metal electrode, and forming a buffer layer on the absorber layer. The method also forms a titanium oxide layer on the buffer layer, wherein a thickness of the titanium oxide layer is greater than 0 and less than 10 nm. The method further forms a transparent conductive oxide layer on the titanium oxide layer. The step of forming the titanium oxide layer is atomic layer deposition (ALD) performed at a temperature of 100 C. to 180 C. with a precursor of titanium tetraisopropoxide.

According to the embodiment, there is provided a solar cell apparatus. The solar cell apparatus includes a back electrode layer on a substrate, a light absorbing layer on the back electrode layer, a buffer layer on the light absorbing layer, a front electrode layer on the buffer layer, and a connection part making contact with the front electrode layer, passing through the light absorbing layer, and making contact with the back electrode layer. The connection part includes a material different from a material constituting the front electrode layer.

The present invention provides a CIGS film substantially free from oxidation of a front surface thereof and a CIGS solar cell employing the CIGS film and substantially free from reduction and variation in conversion efficiency. The CIGS film, which is used as a light absorbing layer for the CIGS solar cell, includes: a first region having a Ga/(In+Ga) ratio progressively reduced along its thickness toward a predetermined first thickness position from a back surface of the CIGS film; a second region having a Ga/(In+Ga) ratio progressively increased along its thickness toward a predetermined second thickness position from the first region; and a third region provided on the second region and having a Ga/(In+Ga) ratio progressively reduced along its thickness toward the front surface of the CIGS film.

An apparatus for deposition of a plurality of elements onto a solar cell substrate that comprises: a housing; a transporting apparatus to transport the substrate in and out of the housing; a first tubing apparatus to deliver powders of a first elements to the housing; a first source material tube located outside of the housing and joined to a feeder tube of the tubing apparatus; a valve located inside of the first source material tube sufficient to block access between the first source material tube and the first feeder tube; a first heating tube located inside of the housing and connected to the first feeder tube; a similar second tubing apparatus to deliver powders of a second elements to the housing; a loading station for loading the substrate onto the transporting apparatus; one or more thermal sources to heat the housing and the first and second heating tube.

A photovoltaic device comprises a back reflective coating structure to provide back scattering of light that passes through the photovoltaic device, an absorber structure containing chalcogenide materials, and a top scattering antireflective structure deposited on the top subcell. Illustratively, a multi-junction structure comprises a bottom subcell deposited on the back reflective coating structure, the bottom subcell having a lower band gap, higher index material embedded therein, to provide lateral propagation of light that passes through the photovoltaic device, and a top subcell deposited on the bottom subcell. The multi-junction structure can comprise chalcogenide materials, in which case the top subcell is embedded with an intermediate band gap absorber material.

A method of manufacture of I-III-VI-absorber photovoltaic cells involves sequential deposition of films comprising one or more of silver and copper, with one or more of aluminum indium and gallium, and one or more of sulfur, selenium, and tellurium, as compounds in multiple thin sublayers to form a composite absorber layer. In an embodiment, the method is adapted to roll-to-roll processing of photovoltaic cells. In an embodiment, the method is adapted to preparation of a CIGS absorber layer having graded composition through the layer of substitutions such as tellurium near the base contact and silver near the heterojunction partner layer, or through gradations in indium and gallium content. In a particular embodiment, the graded composition is enriched in gallium at a base of the layer, and silver at the top of the layer. In an embodiment, each sublayer is deposited by co-evaporation of copper, indium, gallium, and selenium, which react in-situ to form CIGS.

This solar cell is provided with a substrate (11), a first electrode layer (12) which is arranged on the substrate (11), a p-type CZTS light absorption layer (13) which is arranged on the first electrode layer (12) and which contains copper, zinc, tin, and group VI elements including sulfur and selenium, and an n-type second electrode layer (15) which is arranged on the CZTS light absorption layer (13), wherein the sulfur concentration in the group VI elements in the CZTS light absorption layer (13) increases, in the depth direction, from the side facing the second electrode layer (15) towards the side facing the first electrode layer (12).

A hybrid vapor phase-solution phase CZT(S,Se) growth technique is provided. In one aspect, a method of forming a kesterite absorber material on a substrate includes the steps of: depositing a layer of a first kesterite material on the substrate using a vapor phase deposition process, wherein the first kesterite material includes Cu, Zn, Sn, and at least one of S and Se; annealing the first kesterite material to crystallize the first kesterite material; and depositing a layer of a second kesterite material on a side of the first kesterite material opposite the substrate using a solution phase deposition process, wherein the second kesterite material includes Cu, Zn, Sn, and at least one of S and Se, wherein the first kesterite material and the second kesterite material form a multi-layer stack of the absorber material on the substrate. A photovoltaic device and method of formation thereof are also provided.

A device includes a bottom contact layer on a substrate, an absorber layer on the bottom contact layer, a cap layer on the absorber layer, a hole blocker layer on the cap layer, and a top contact layer on the hole blocker layer. The absorber layer includes oxygen-annealed copper, indium, gallium and selenium. The device has a quantum efficiency greater than about 50%, measured at a voltage of about 1 volt and at a wavelength of about 940 nanometers.