Bandgap-tunable perovskite compositions are provided having the formula CsPb(A.sub.xB.sub.y).sub.3, wherein A and B are each a halogen. The mixed halide perovskite composition has a morphology which suppresses phase segregation to stabilize a tuned bandgap of the mixed halide perovskite composition. For example, the perovskite may be in the form of nanocrystals embedded in a non-perovskite matrix, which, for example, may have the formula Cs.sub.4Pb(A.sub.xB.sub.y).sub.6, wherein A and B are each a halogen. Solar cells and light-emitting diodes comprising the mixed perovskite compositions are also provided.

Bandgap-tunable perovskite compositions are provided having the formula CsPb(A.sub.xB.sub.y).sub.3, wherein A and B are each a halogen. The mixed halide perovskite composition has a morphology which suppresses phase segregation to stabilize a tuned bandgap of the mixed halide perovskite composition. For example, the perovskite may be in the form of nanocrystals embedded in a non-perovskite matrix, which, for example, may have the formula Cs.sub.4Pb(A.sub.xB.sub.y).sub.6, wherein A and B are each a halogen. Solar cells and light-emitting diodes comprising the mixed perovskite compositions are also provided.

Materials and methods for preparing Cu.sub.2XSnY.sub.4 nanoparticles, wherein X is Zn, Cd, Hg, Ni, Co, Mn or Fe and Y is S or Se, (CXTY) are disclosed herein. The nanoparticles can be used to make layers for use in thin film photovoltaic (PV) cells. The CXTY materials are prepared by a colloidal synthesis in the presence of labile organo-chalcogens. The organo-chalcogens serves as both a chalcogen source for the nanoparticles and as a capping ligand for the nanoparticles.

Materials and methods for preparing Cu.sub.2XSnY.sub.4 nanoparticles, wherein X is Zn, Cd, Hg, Ni, Co, Mn or Fe and Y is S or Se, (CXTY) are disclosed herein. The nanoparticles can be used to make layers for use in thin film photovoltaic (PV) cells. The CXTY materials are prepared by a colloidal synthesis in the presence of labile organo-chalcogens. The organo-chalcogens serves as both a chalcogen source for the nanoparticles and as a capping ligand for the nanoparticles.

A device for sensing suspension operations or biometrics includes a light emitting module and a sensing layer. The light emitting module and the sensing layer are sequentially stacked. The light emitting module includes a plurality of light emitting elements emitting light near the infrared and the sensing layer includes a plurality of quantum dot thin film transistors. The quantum dot thin film transistor includes an active layer and quantum dots covering the active layer. The near-infrared light emitted by the plurality of light emitting elements is reflected by an animate object and received by the quantum dot thin film transistors. The sensing device can better sense suspension operations or biometrics. A method for the procedure is also disclosed.

A device for sensing suspension operations or biometrics includes a light emitting module and a sensing layer. The light emitting module and the sensing layer are sequentially stacked. The light emitting module includes a plurality of light emitting elements emitting light near the infrared and the sensing layer includes a plurality of quantum dot thin film transistors. The quantum dot thin film transistor includes an active layer and quantum dots covering the active layer. The near-infrared light emitted by the plurality of light emitting elements is reflected by an animate object and received by the quantum dot thin film transistors. The sensing device can better sense suspension operations or biometrics. A method for the procedure is also disclosed.

A semiconductor stacked body includes: a first semiconductor layer containing a group III-V compound semiconductor and being a layer whose conductivity type is a first conductivity type; a quantum-well light-receiving layer containing a group III-V compound semiconductor; a second semiconductor layer containing a group III-V compound semiconductor; and a third semiconductor layer containing a group III-V compound semiconductor and being a layer whose conductivity type is a second conductivity type. The first semiconductor layer, the quantum-well light-receiving layer, the second semiconductor layer, and the third semiconductor layer are stacked in this order. The concentration of an impurity that generates a carrier of the second conductivity type is 110.sup.14 cm.sup.3 or more and 110.sup.17 cm.sup.3 or less in the second semiconductor layer.

A multispectral imaging device comprises a first photoelectric conversion module and a second photoelectric conversion module. The first photoelectric conversion module further includes a first photoelectric conversion layer located between a first conducting layer and a second conducting layer. The first conducting layer, coupled to a first constant potential, is configured to allow visible light and infrared light to pass through. The first photoelectric conversion layer is configured to convert the visible light into a first electrical signal. The second photoelectric conversion module, formed on a silicon substrate, is configured to receive the infrared light coming from the first photoelectric conversion module. The second photoelectric conversion layer located between a third conducting layer and a fourth conducting layer, wherein the third conducting layer is configured to allow the infrared light passing through, the second photoelectric conversion layer is configured to convert the infrared light into a second electrical signal.

A multispectral imaging device comprises a first photoelectric conversion module and a second photoelectric conversion module. The first photoelectric conversion module further includes a first photoelectric conversion layer located between a first conducting layer and a second conducting layer. The first conducting layer, coupled to a first constant potential, is configured to allow visible light and infrared light to pass through. The first photoelectric conversion layer is configured to convert the visible light into a first electrical signal. The second photoelectric conversion module, formed on a silicon substrate, is configured to receive the infrared light coming from the first photoelectric conversion module. The second photoelectric conversion layer located between a third conducting layer and a fourth conducting layer, wherein the third conducting layer is configured to allow the infrared light passing through, the second photoelectric conversion layer is configured to convert the infrared light into a second electrical signal.

A light receiving device includes: a photoelectric conversion layer that includes a first compound semiconductor, and absorbs a wavelength in an infrared region to generate electrical charges; a plurality of contact layers that include a second compound semiconductor, and are provided on the photoelectric conversion layer at spacing intervals with respect to one another; and a covering layer that is formed to cover a portion corresponding to the spacing intervals of a front surface of the photoelectric conversion layer and side surfaces of the respective contact layers, and includes a Group IV semiconductor.