The present disclosure relates to a solid-state light emitting device, a solid state light absorbing device and methods for fabricating the same. In particular, the present disclosure relates to a light emitting device comprising: a transition metal dichalcolgenide layer disposed between two layers of a material with a bandgap larger than the transition metal dichalcolgenide layer; a plurality of nanoparticles embedded into the transition metal dichalcolgenide layer and being arranged to form a plurality of allowable energy levels within the bandgap of the transition metal dichalcolgenide layer; and electrodes arranged to apply a voltage across the two layers and the transition metal dichalcolgenide layer; wherein, when a voltage within a predetermined range is applied to the electrodes, photons with a wavelength within a specific wavelength range are emitted by the device and the wavelength range can be varied by varying the voltage across the two layers and the transition metal dichalcolgenide layer.

A source and drain electrode are spaced apart by an optically exposed gate region above a surface photovoltage effect (SPV) bulk. A two-dimensional material is deposited upon the gate region. The gate region is activated by exposure to an ultrafast light pulse, which may be infrared or near-infrared, and may be a focused collimated laser pulse with a sub-picosecond width. The pulse causes electron-hole pair generation resulting in band bending in the SPV material, which generates an electric field within the 2D material, thereby modifying the electronic properties between source and drain via a field-effect. After passage of the pulse, conduction continues in the device until the conductive electron-hole pairs recombine during the SPV decay time. The two-dimensional material may comprise a crystalline atomic monolayer. The activation is repeatable with subsequent pulses, resulting in the device cycling on and off within timescales less than 200 picoseconds.

A photoexcitable material includes: a solid solution of MN (where M is at least one of gallium, aluminum and indium) and ZnO, wherein the photoexcitable material includes 30 to 70 mol % ZnO and has a band gap energy of 2.20 eV or less.

A photoexcitable material includes: a solid solution of MN (where M is at least one of gallium, aluminum and indium) and ZnO, wherein the photoexcitable material includes 30 to 70 mol % ZnO and has a band gap energy of 2.20 eV or less.

A photovoltaic device having a perovskite PV cell wherein the PV device operates, for example during start-up, initially in a bias-voltage operating mode, in which a bias voltage is applied to the perovskite PV cell of the PV device. The bias voltage or the energy needed for same can advantageously be drawn from the power electronics associated with the perovskite PV cell.

A composition of matter includes an n-type semiconductor. At least a portion of the semiconductor has the crystal structure of the chemical compound represented by FeWO.sub.4. The portion of the semiconductor having the crystal structure of FeWO.sub.4 includes iron and tungsten. A photoanode can have a light-absorbing layer that includes or consists of the semiconductor. A solar fuels generator can include the photoanode.

A composition of matter includes an n-type semiconductor. At least a portion of the semiconductor has the crystal structure of the chemical compound represented by FeWO.sub.4. The portion of the semiconductor having the crystal structure of FeWO.sub.4 includes iron and tungsten. A photoanode can have a light-absorbing layer that includes or consists of the semiconductor. A solar fuels generator can include the photoanode.

A photodetector based on PtSe.sub.2 and a silicon nanopillar array includes a PMMA light-transmitting protective layer, a graphene transparent top electrode, a silicon nanopillar array structure coated with few-layer PtSe.sub.2, and metal electrodes of the graphene transparent top electrode and the silicon nanopillar array structure. A method for preparing the photodetector includes steps of: preparing graphene with a CVD method; preparing a silicon nanopillar array structure through dry etching; coating few-layer PtSe.sub.2 on surfaces of the silicon nano-pillar array structure through laser interference enhanced induction CVD; preparing graphene transparent top electrode; and magnetron-sputtering metal electrodes. The photodetector prepared by the present invention has a detection range from visible light to near-infrared wavebands. The silicon nanopillar array structure enhances light absorption of the detector, so that the detector has high sensitivity, simple structure and strong practicability.

The photoelectric conversion layer of an embodiment is based on Cu.sub.2O, contains at least one p-type dopant selected from the group consisting of Ge, Ta, and In, and has a band gap of equal to or more than 2.10 eV and equal to or less than 2.30 eV.

Photovoltaic devices, and methods of fabricating photovoltaic devices. The photovoltaic devices may include a first electrode, at least one quantum dot layer, at least one semiconductor layer, and a second electrode. The first electrode may include a layer including Cr and one or more silver contacts.