According to one embodiment, an optical sensor device includes an insulating substrate, a first conductive layer and an optical sensor element disposed between the insulating substrate and the first conductive layer. The optical sensor element is electrically connected to the first conductive layer and covered by the first conductive layer. The optical sensor element includes a first semiconductor layer formed of an oxide semiconductor and controls an amount of charge flowing to the first conductive layer according to an amount of incident light to the first semiconductor layer.

According to one embodiment, an optical sensor device includes an insulating substrate, a first conductive layer and an optical sensor element disposed between the insulating substrate and the first conductive layer. The optical sensor element is electrically connected to the first conductive layer and covered by the first conductive layer. The optical sensor element includes a first semiconductor layer formed of an oxide semiconductor and controls an amount of charge flowing to the first conductive layer according to an amount of incident light to the first semiconductor layer.

The solar cell of embodiments includes a transparent first electrode, a photoelectric conversion layer mainly containing cuprous oxide on the first electrode, an n-type layer on the photoelectric conversion layer, and a transparent second electrode on the n-type layer. A mixed region or/and a mixed layer are present on the n-type layer side of the photoelectric conversion layer, and the mixed region and the mixed layer contain elements belonging to a first group, a second group, and a third group. The first group is one or more elements selected from the group consisting of Zn and Sn, the second group is one or more elements selected from the group consisting of Y, Sc, V, Cr, Mn, Fe, Ni, Zr, B, Al, Ga, Nb, Mo, Ti, F, Cl, Br, and I, and the third group is one or more elements selected from the group consisting of Ge and Si.

The solar cell of embodiments includes a transparent first electrode, a photoelectric conversion layer mainly containing cuprous oxide on the first electrode, an n-type layer on the photoelectric conversion layer, and a transparent second electrode on the n-type layer. A mixed region or/and a mixed layer are present on the n-type layer side of the photoelectric conversion layer, and the mixed region and the mixed layer contain elements belonging to a first group, a second group, and a third group. The first group is one or more elements selected from the group consisting of Zn and Sn, the second group is one or more elements selected from the group consisting of Y, Sc, V, Cr, Mn, Fe, Ni, Zr, B, Al, Ga, Nb, Mo, Ti, F, Cl, Br, and I, and the third group is one or more elements selected from the group consisting of Ge and Si.

A method for growing a semiconductor material over a Si-based substrate includes providing the Si-based substrate; growing a monocrystalline refractory-metal ceramic film directly over the Si-based substrate; and depositing a semiconductor film directly over the monocrystalline refractory-metal ceramic film. The monocrystalline refractory-metal ceramic film has a thickness less than 300 nm.

A method for growing a semiconductor material over a Si-based substrate includes providing the Si-based substrate; growing a monocrystalline refractory-metal ceramic film directly over the Si-based substrate; and depositing a semiconductor film directly over the monocrystalline refractory-metal ceramic film. The monocrystalline refractory-metal ceramic film has a thickness less than 300 nm.

A method of synthesis of two-dimensional (2D) nanoflakes comprises the cutting of prefabricated nanoparticles. The method allows high control over the shape, size and composition of the 2D nanoflakes, and can be used to produce material with uniform properties in large quantities. Van der Waals heterostructure devices are prepared by fabricating nanoparticles, chemically cutting the nanoparticles to form nanoflakes, dispersing the nanoflakes in a solvent to form an ink, and depositing the ink to form a thin film.

A method of synthesis of two-dimensional (2D) nanoflakes comprises the cutting of prefabricated nanoparticles. The method allows high control over the shape, size and composition of the 2D nanoflakes, and can be used to produce material with uniform properties in large quantities. Van der Waals heterostructure devices are prepared by fabricating nanoparticles, chemically cutting the nanoparticles to form nanoflakes, dispersing the nanoflakes in a solvent to form an ink, and depositing the ink to form a thin film.

Provided are a metal chalcogenide thin film and a method and device for manufacturing the same. The metal chalcogenide thin film includes a transition metal element and a chalcogen element, and at least one of the transition metal element and the chalcogen element having a composition gradient along the surface of the metal chalcogenide thin film, the composition gradient being an in-plane composition gradient. The metal chalcogenide thin film may be prepared by using a manufacturing method including providing a transition metal precursor and a chalcogen precursor on a substrate by using a confined reaction space in such a manner that at least one of the transition metal precursor and the chalcogen precursor forms a concentration gradient according to a position on the surface of the substrate; and heat-treating the substrate.

A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode, which mainly contains a compound represented by Ga.sub.x1M1.sub.x2M2.sub.x3M3.sub.x4M4.sub.x5O.sub.x6, the M1 being Hf and/or Zr, the M2 being one or more selected from the group consisting of In, Ti, and Zn, the M3 being Al and/or B, the M4 is one or more selected from the group consisting of Sn, Si, and Ge, the x1, the x2, and the x6 being more than 0, the x3, the x4, and the x5 being 0 or more, and the x6 when a sum of the x1, the x2, the x3, the x4, and the x5 is 2 being 3.0 or more and 3.8 or less.