Oxide electron selective contacts for perovskite solar cells are provided. In one aspect, a method of forming a perovskite solar cell is provided. The method includes the steps of: depositing a layer of a hole transporting material on a substrate; forming a perovskite absorber on the hole transporting material; depositing an oxide electron transporting material on the perovskite absorber; and forming a top electrode on the oxide electron transporting material. Perovskite solar cells and tandem photovoltaic devices are also provided.

A photovoltaic device includes a substrate, a back contact comprising a stable low-work function material, a photovoltaic absorber material layer comprising Ag.sub.2ZnSn(S,Se).sub.4 (AZTSSe) on a side of the back contact opposite the substrate, wherein the back contact forms an Ohmic contact with the photovoltaic absorber material layer, a buffer layer or Schottky contact layer on a side of the absorber layer opposite the back contact, and a top electrode on a side of the buffer layer opposite the absorber layer.

The present invention relates to a CZTSe-based composite thin film, a method for preparing the CZTSe-based composite thin film, a solar cell using the CZTSe-based composite thin film, and a method for preparing the solar cell using the CZTSe-based composite thin film.

A method for fabricating a photovoltaic device includes forming a polycrystalline absorber layer including CuZnSnS(Se) (CZTSSe) over a substrate. The absorber layer is rapid thermal annealed in a sealed chamber having elemental sulfur within the chamber. A sulfur content profile is graded in the absorber layer in accordance with a size of the elemental sulfur and an anneal temperature to provide a graduated bandgap profile for the absorber layer. Additional layers are formed on the absorber layer to complete the photovoltaic device.

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.

Techniques for forming a transparent conducting oxide (TCO) top contact using a low temperature process are provided. In one aspect of the invention, a method of forming a TCO on a substrate is provided. The method includes the steps of: generating a source gas of the TCO using e-beam evaporation; generating atomic oxygen using RF plasma; and contacting the substrate with the TCO source gas and the atomic oxygen under conditions sufficient to form the TCO on the substrate. A photovoltaic device is also provided which includes a bottom cell; and a perovskite-based top cell on the kesterite-based bottom cell. The perovskite-based top cell includes a top electrode formed from a TCO.

Techniques for improved kesterite film production through annealing chamber conditioning to achieve solar cells with a power conversion efficiency of greater than 12% are provided. In one aspect, a method of conditioning an annealing chamber for forming a kesterite film is provided. The method includes the step of: coating one or more inner surfaces of the annealing chamber with a film containing Sn and at least one of S and Se. A method for forming a kesterite film, a method for forming a solar cell, and a solar cell are also provided.

Kesterite-based homojunction photovoltaic devices are provided. The photovoltaic devices include a p-type semiconductor layer including a copper-zinc-tin containing chalcogenide compound and an n-type semiconductor layer including a silver-zinc-tin containing chalcogenide compound having a crystalline structure the same as a crystalline structure the copper-zinc-tin containing chalcogenide compound.

A photovoltaic device includes a substrate, a first electrode formed on the substrate and a p-type absorber layer including a chalcogenide compound. An n-type layer includes a zinc oxysulfide material having a sulfur content adjusted to match a feature of the absorber layer. A transparent contact is formed on the n-type layer.