A perovskite-silicon tandem cell capable of absorbing solar radiation with energy lower than that of 1.12 eV, i.e., the bandgap of crystalline silicon—corresponding to the wavelength of 1100 nm. Ho.sup.3+ can absorb photons of wavelength range 1120 to 1190 nm, Tm.sup.3+, 1190 to 1260 nm, and Er.sup.3+, 1145 to 1580 nm, but up-conversion can be achieved using Ho.sup.3+, Tm.sup.3+, and Er.sup.3+-doped metal oxide, such as ZrO.sub.2, in perovskite-silicon tandem solar cells. Doped metal oxides, such as ZrO.sub.2 can also work as selective contacts. Such perovskite-silicon tandem structures can achieve over 30% solar energy conversion efficiency.

Tandem solar cell configurations are provided where at least one of the cells is a metal chalcogenide cell. A four-terminal tandem solar cell configuration has two electrically independent solar cells stacked on each other. A two-terminal solar cell configuration has two electrically coupled solar cells (same current through both cells) stacked on each other. Carrier selective contacts can be used to make contact to the metal chalcogenide cell (s) to alleviate the troublesome Fermi level pinning issue. Carrier-selective contacts can also remove the need to provide doping of the metal chalcogenide. Doping of the metal chalcogenide can be provided by charge transfer. These two ideas can be practiced independently or together in any combination.

Tandem solar cell configurations are provided where at least one of the cells is a metal chalcogenide cell. A four-terminal tandem solar cell configuration has two electrically independent solar cells stacked on each other. A two-terminal solar cell configuration has two electrically coupled solar cells (same current through both cells) stacked on each other. Carrier selective contacts can be used to make contact to the metal chalcogenide cell (s) to alleviate the troublesome Fermi level pinning issue. Carrier-selective contacts can also remove the need to provide doping of the metal chalcogenide. Doping of the metal chalcogenide can be provided by charge transfer. These two ideas can be practiced independently or together in any combination.

An apparatus, system, and method for detecting light having a specified or first wavelength. The apparatus includes a substrate that generates charge separation in the presence of light having the first wavelength. An active material is deposited onto the substrate. The active material is configured to conduct current in the presence of light having a second wavelength. Two electrodes are connected to the active material. Light having the second wavelength is constantly applied to the active material and the current is monitored via the electrodes. The active material will conduct zero or minimal current via the electrodes if the substrate does not generate charge separation. Detection the presence of light having the first wavelength may be detected upon the detection of current via the two electrodes. The first wavelength may be non-visible light and the second wavelength may be visible light.

Methods of fabricating nanocrystals are disclosed. Such methods may include providing copper sulfide core nanocrystals and providing a lead precursor. Moreover, the copper sulfide core nanocrystals may be reacted with the lead precursor to generate copper doped lead sulfide nanocrystals. Related nanocrystals and optoelectronic devices are also disclosed.

An apparatus, system, and method for detecting light having a specified or first wavelength. The apparatus includes a substrate that generates charge separation in the presence of light having the first wavelength. An active material is deposited onto the substrate. The active material is configured to conduct current in the presence of light having a second wavelength. Two electrodes are connected to the active material. Light having the second wavelength is constantly applied to the active material and the current is monitored via the electrodes. The active material will conduct zero or minimal current via the electrodes if the substrate does not generate charge separation. Detection the presence of light having the first wavelength may be detected upon the detection of current via the two electrodes. The first wavelength may be non-visible light and the second wavelength may be visible light.

Provided are methods for obtaining n-type doped metal chalcogenide quantum dot solid-state films. In some embodiments, the methods include forming an metal chalcogenide quantum dot solid-state film, carrying out a n-doping process on the metal chalcogenide quantum dots of the metal chalcogenide quantum dot solid-state film so that they exhibit intraband absorption, wherein the process includes partially substituting chalcogen atoms by halogen atoms in the metal chalcogenide quantum dots and providing a substance on the plurality of metal chalcogenide quantum dots, to avoid oxygen p-doping of the metal chalcogenide quantum dots. Also provided are optoelectronic devices, which in some embodiments can include an n-type doped metal chalcogenide quantum dot solid-state film (A) obtained by a method as disclosed herein and first (E1) and second (E2) electrodes in physical contact with two respective distanced regions of the film (A).

A perovskite-silicon tandem cell capable of absorbing solar radiation with energy lower than that of 1.12 eV, i.e., the bandgap of crystalline silicon—corresponding to the wavelength of 1100 nm. Ho.sup.3+ can absorb photons of wavelength range 1120 to 1190 nm, Tm.sup.3+, 1190 to 1260 nm, and Er.sup.3+, 1145 to 1580 nm, but up-conversion can be achieved using Ho.sup.3+, Tm.sup.3+, and Er.sup.3+-doped metal oxide, such as ZrO.sub.2, in perovskite-silicon tandem solar cells. Doped metal oxides, such as ZrO.sub.2 can also work as selective contacts. Such perovskite-silicon tandem structures can achieve over 30% solar energy conversion efficiency.

Provided are methods for obtaining n-type doped metal chalcogenide quantum dot solid-state films. In some embodiments, the methods include forming an metal chalcogenide quantum dot solid-state film, carrying out a n-doping process on the metal chalcogenide quantum dots of the metal chalcogenide quantum dot solid-state film so that they exhibit intraband absorption, wherein the process includes partially substituting chalcogen atoms by halogen atoms in the metal chalcogenide quantum dots and providing a substance on the plurality of metal chalcogenide quantum dots, to avoid oxygen p-doping of the metal chalcogenide quantum dots. Also provided are optoelectronic devices, which in some embodiments can include an n-type doped metal chalcogenide quantum dot solid-state film (A) obtained by a method as disclosed herein and first (E1) and second (E2) electrodes in physical contact with two respective distanced regions of the film (A).

The present invention relates to a light absorption layer for forming a photoelectric conversion element and an intermediate-band solar cell excellent in quantum efficiency of two-step light absorption, a photoelectric conversion element having the light absorption layer, and an intermediate-band solar cell. The present invention also relates to a method for manufacturing a light absorption layer having an intermediate-band, using a wet process, which method can be expected to greatly reduce costs and expand to use for flexible substrates. The light absorption layer of the present invention has an intermediate-band, wherein quantum dots are dispersed in a matrix of a bulk semiconductor having a band gap energy of 2.0 eV or more and 3.0 eV or less.