The process comprises treating 90-190 g titanium (IV) chloride in 10-100 ml de-ionized water for preparing Titanium cation (Ti.sup.4+); treating 130-275 ml potassium persulfate in 10-100 ml double-distilled water and keeping at constant temperature to obtain sulphate/oxide; dipping substrates into titanium (IV) chloride solution and re-dipping in de-ionized water to remove loosely bonded ions, if could be any; dipping substrates into potassium persulfate solution and re-dipping in de-ionized water to remove loosely bonded ions, if could be any, and keeping at 50-90° C. for complete one cycle; treating obtained Titanium cation (Ti.sup.4+) with sulphate/oxide and obtaining whitish layer on the substrate surface by necked eyes after about 10-15 cycles, suggesting initiation of film formation, wherein the deposition thickness of TiO.sub.2 layer is increased from 0.3-2.0-micron on determined 5-50 deposition cycles; and rinsing deposited films with de-ionized water and air annealed at 400-600° C. temperature to obtain anatase TiO.sub.2.

The invention relates to perovskite compounds which have surprisingly good emission properties, particularly photoluminescent emission properties, in the blue region of the visible spectrum. These perovskites contain a mixture of cations or a mixture of halides, or both. The invention also relates to a photoactive material containing the perovskite species of the invention; to an optoelectronic device containing the photoactive material of the invention; to a method of producing blue light; and to the use of the photoactive material of the invention to emit blue light or as a phosphor.

A solar cell 100 includes a substrate 1, a first electrode 6, an electron transport layer 2, a first photoelectric conversion layer 3, and a coating layer 5. The first photoelectric conversion layer 3 is disposed between the first electrode 6 and the substrate 1. The substrate 1 has a first main surface and a second main surface, and the second main surface has an uneven structure. The electron transport layer 2 has a first main surface and a second main surface, and the first main surface and the second main surface each have an uneven structure. The first photoelectric conversion layer 3 has a first main surface and a second main surface. The second main surface of the substrate 1 faces the first main surface of the electron transport layer 2.

There is provided a photodetector element including a first electrode layer; a second electrode layer; a photoelectric conversion layer provided between the first electrode layer and the second electrode layer; an electron transport layer provided between the first electrode layer and the photoelectric conversion layer; and a hole transport layer provided between the photoelectric conversion layer and the second electrode layer, in which the photoelectric conversion layer contains an aggregate of semiconductor quantum dots that contain a metal atom and contains a ligand coordinated to the semiconductor quantum dot, the hole transport layer contains an organic semiconductor, and the second electrode layer is formed of a metal material containing at least one metal atom selected from Au, Pt, Ir, Pd, Cu, Pb, Sn, Zn, Ti, W, Mo, Ta, Ge, Ni, Cr, or In. There is also provided an image sensor including the photodetector element.

The present invention relates to a working electrode (1a) for a photovoltaic device, comprising a light absorbing layer (3) and a conductive layer (6) arranged in electrical contact with the light absorbing layer (3), and the light absorbing layer (3) comprises a light absorbing photovoltaic material consisting of a plurality of dye molecules. The light absorbing layer (3) is formed by a layer of a plurality of clusters (7), whereby each cluster (7) is formed by dye molecules and each dye molecule in the cluster (7) is bonded to its adjacent dye molecules.

There is provided a multi-junction photovoltaic device comprising a first sub-cell disposed over a second sub-cell, the first sub-cell comprising a photoactive region comprising a layer of perovskite material and the second sub-cell comprising a silicon heterojunction (SHJ).

An optical element includes a photoelectric conversion film and an inorganic substance-containing film containing at least one selected from the group consisting of a metal nitride and a metal oxynitride, in which the photoelectric conversion film contains a quantum dot or at least one compound semiconductor selected from the group consisting of a III-V group compound semiconductor, a II-VI group compound semiconductor, and a IV-IV group compound semiconductor, and the optical density of an inorganic substance-containing film is 0.5 or more per 1.0 μm of a film thickness at a wavelength of 1,550 nm.

The invention relates to an optoelectronic and/or photoelectrochemical device including a conductive support layer, n-type semiconductor, a sensitizer or light-absorber layer, a hole transporting layer, a spacer layer and a back contact, wherein the n-type semiconductor is in contact with the sensitizer or light-absorber layer, the sensitizer or light-absorber layer includes a perovskite or metal halide perovskite material, the hole transporting layer is in direct contact with the sensitizer or light-absorber layer and includes an inorganic hole transporting material or inorganic p-type semiconductor, the spacer layer is between the hole transporting layer and the back contact and includes a material being different from the inorganic hole transporting material and the material of the back contact.

A method for preparing photoactive perovskite materials. The method comprises the step of preparing a germanium halide precursor ink. Preparing a germanium halide precursor ink comprises the steps of: introducing a germanium halide into a vessel, introducing a first solvent to the vessel, and contacting the germanium halide with the first solvent to dissolve the germanium halide. The method further comprises depositing the germanium halide precursor ink onto a substrate, drying the germanium halide precursor ink to form a thin film, annealing the thin film, and rinsing the thin film with a second solvent and a salt.

A photovoltaic device includes a semi-transparent substrate and at least one translucent photovoltaic cell. The photovoltaic cell includes a stack of layers disposed on the substrate, wherein the stack has apertures extending through it at least partially, contain a functionalizing agent and are uniformly distributed within the photovoltaic cell.