Abstract: There is provided a method of producing a photovoltaic device comprising a photoactive region comprising a layer of perovskite material, wherein the layer of perovskite material is disposed on a surface that has a roughness average (Ra) or root mean square roughness (Rrms) of greater than or equal to 50 nm. The method comprises using vapour deposition to deposit a substantially continuous and conformal solid layer comprising one or more initial precursor compounds of the perovskite material, and subsequently treating the solid layer with one or more further precursor compounds to form a substantially continuous and conformal solid layer of the perovskite material on the rough surface. There is also provided a photovoltaic device comprising a photoactive region comprising a layer of perovskite material disposed using the method.

Abstract: There is provided a method of producing a photovoltaic device comprising a photoactive region comprising a layer of perovskite material, wherein the layer of perovskite material is disposed on a surface that has a roughness average (Ra) or root mean square roughness (Rrms) of greater than or equal to 50 nm. The method comprises using vapour deposition to deposit a substantially continuous and conformal solid layer comprising one or more initial precursor compounds of the perovskite material, and subsequently treating the solid layer with one or more further precursor compounds to form a substantially continuous and conformal solid layer of the perovskite material on the rough surface. There is also provided a photovoltaic device comprising a photoactive region comprising a layer of perovskite material disposed using the method.

Abstract: A multi-junction photovoltaic device comprising a layer of metal oxynitride between a first sub-cell and a second sub-cell is disclosed, the first sub-cell having a layer comprising a perovskite light absorber material. In addition, a method of manufacturing said multi junction photovoltaic device is disclosed. The metal oxynitride is preferably titanium oxynitride. Advantageously, the device may be produced in a simple, fast, consistent and inexpensive manner, whilst the properties of the titanium oxynitride layer may be tuned to avoid the occurrence of local shunt paths and to reduce reflection losses.

Abstract: The present invention provides a method of forming a crystalline or polycrystalline layer of an organic-inorganic metal halide perovskite material comprising a three-dimensional crystal structure represented by the formula AMX3, in which A represents an organic cation or a mixture of two or more different cations, at least one of which is an organic cation, M represents a divalent metal cation or a mixture of two or more different divalent metal cations, and X represents halide anions which are the same or different, the method comprising the steps of: (i) forming a first layer on the surface of a substrate, the first layer comprising an organic-inorganic metal halide perovskite material having a planar, layered two-dimensional crystal structure (ii) reacting the first layer with one or more organic halides to form the crystalline or polycrystalline layer comprising an organic-inorganic metal halide perovskite material having the formula AMX3.

Abstract: There is provided a photovoltaic device that comprises a photoactive region, the photoactive region comprising a perovskite material of general formula A1-xA?xBX3-yX?y, wherein A is a formamidinium cation (HC(NH)2)2+), A? is a caesium cation (Cs+) B is at least one divalent inorganic cation, X is iodide and X is bromide, and x is greater than 0 and equal to or less than 0.4 and y is greater than 0 and less than or equal to 3. There is also provided a method of producing a photovoltaic device comprising a photoactive region comprising the perovskite material, and formulations for use in the formation of the perovskite material.

Abstract: The present invention provides a method of forming a crystalline or polycrystalline layer of an organic-inorganic metal halide perovskite material comprising a three-dimensional crystal structure represented by the formula AMX 3, in which A represents an organic cation or a mixture of two or more different cations, at least one of which is an organic cation, M represents a divalent metal cation or a mixture of two or more different divalent metal cations, and X represents halide anions which are the same or different, the method comprising the steps of: (i) forming a first layer on the surface of a substrate, the first layer comprising an organic-inorganic metal halide perovskite material having a planar, layered two-dimensional crystal structure (ii) reacting the first layer with one or more organic halides to form the crystalline or polycrystalline layer comprising an organic-inorganic metal halide perovskite material having the formula AMX 3.

Abstract: There is provided a photovoltaic device that comprises a photoactive region, the photoactive region comprising a perovskite material of general formula A1-xA?xBX3-yX?y, wherein A is a formamidinium cation (HC(NH)2)2+), A? is a caesium cation (Cs+) B is at least one divalent inorganic cation, X is iodide and X is bromide, and x is greater than 0 and equal to or less than 0.4 and y is greater than 0 and less than or equal to 3. There is also provided a method of producing a photovoltaic device comprising a photoactive region comprising the perovskite material, and formulations for use in the formation of the perovskite material.

Abstract: There is provided a photovoltaic device that comprises a photoactive region, the photoactive region comprising a perovskite material of general formula A1?xA?xBX3?yX?y wherein A is a formamidinium cation ((HC(NH2)2)+), A? is a caesium cation (Cs+), B is at least one divalent inorganic cation, X is iodide and X? is bromide, and x is greater than 0 and equal to or less than 0.4 and y is greater than 0 and less than or equal to 3. There is also provided a method of producing a photovoltaic device comprising a photoactive region comprising the perovskite material, and formulations for use in the formation of the perovskite material.

Abstract: There is provided a method of producing a photovoltaic device comprising a photoactive region comprising a layer of perovskite material, wherein the layer of perovskite material is disposed on a surface that has a roughness average (Ra) or root mean square roughness (Rrms) of greater than or equal to 50 nm. The method comprises using vapour deposition to deposit a substantially continuous and conformal solid layer comprising one or more initial precursor compounds of the perovskite material, and subsequently treating the solid layer with one or more further precursor compounds to form a substantially continuous and conformal solid layer of the perovskite material on the rough surface. There is also provided a photovoltaic device comprising a photoactive region comprising a layer of perovskite material disposed using the method.

Abstract: There is provided a photovoltaic device that comprises a photoactive region, the photoactive region comprising a perovskite material of general formula A1-xA?xBX3-yX?, wherein A is a formamidinium cation (HC(NH)2)2+), A? is a caesium cation (Cs+)B is at least one divalent inorganic cation, X is iodide and X? is bromide, and x is greater than 0 and equal to or less than 0.4 and y is greater than 0 and less than or equal to 3. There is also provided a method of producing a photovoltaic device comprising a photoactive region comprising the perovskite material, and formulations for use in the formation of the perovskite material.