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With the help of the SCAPS simulation program, this study investigates the possible buffer layer in copper zinc tin sulfide (CZTS)/zinc oxide (ZnO) thin-film solar cells. The tin sulfide (SnS${}_2)$ and cadmium sulfide (CdS) are taken into consideration. Based on electronic band structure analysis, SnS₂ exhibits a more favorable alignment of the conduction band than CZTS, which minimizes the barrier to energy transfer. SnS₂ buffer layer showed enhanced carrier generation because of its higher absorption coefficient. Quantum efficiency plots highlighted SnS₂’s superior performance in the 400–800nm range, where CZTS strongly absorbs. The ${\mathrm{\text{SnS}}}_2$ buffer layer solar cell exhibited a larger J–V curve area, driven by a higher short-circuit current density ($J_{\mathrm{\text{sc}}}$.) of 24.27mA/cm² compared to 23.69mA/cm² for CdS, achieving an impressive 15.71% efficiency versus 15.35% for CdS. Because of improved band alignment, enhanced charge generation and higher quantum efficiency, ${\mathrm{\text{SnS}}}_2$ is proving to be a promising buffer layer for high-efficiency CZTS solar cells.

Recent trends of photovoltaics account for the conversion efficiency limit making them more cost effective. To achieve this we have to leave the golden era of silicon cell and make a path towards III–V compound semiconductor groups to take advantages like bandgap engineering by alloying these compounds. In this work we have used a low bandgap GaSb material and designed a single junction (SJ) cell with a conversion efficiency of 32.98%. SILVACO ATLAS TCAD simulator has been used to simulate the proposed model using both Ray Tracing and Transfer Matrix Method (under 1 sun and 1000 sun of AM1.5G spectrum). A detailed analyses of photogeneration rate, spectral response, potential developed, external quantum efficiency (EQE), internal quantum efficiency (IQE), short-circuit current density (J${}_{\mathrm{\text{SC}}}$), open-circuit voltage (V${}_{\mathrm{\text{OC}}}$), fill factor (FF) and conversion efficiency ($\eta$) are discussed. The obtained results are compared with previously reported SJ solar cell reports.

The built-in electric field of exponential doping can promote the concentration of the photogenerated carrier center to the top surface of the nanowire. The external electric field also can bend the motion trajectory of the emitted electrons toward the collecting side. These field-assisted methods promote the quantum efficiency. In this paper, the emission theory of a single GaN nanowire photocathode is studied for the first time. The effects of height and width of the nanowire, wavelength, intensity of electric field on quantum efficiency of uniformly doped or exponentially doped GaN nanowire photocathodes were explored. It shows that the top of the exponentially doped cathode has a higher quantum efficiency than uniformly doped cathode. With the absence of the field, quantum efficiency of a uniformly doped cathode reaches a maximum value of 55.29% when the width is 150 nm and the wavelength is 220 nm. The form of exponentially doped cathode can generate an internal field. With the internal field, a maximum value rises 56.73% when the height is 900 nm and the wavelength is 230 nm. The theoretical results can direct the preparation of this kind of photocathode.

To enhance the near-infrared response of photocathodes in the application of image detection, two kinds of multilayer complex structures of GaAs-based photocathodes are developed by changing the structure of the buffer layer underneath the emission layer, wherein one is the graded bandgap structure, and the other is the distributed Bragg reflector (DBR) structure. The theoretical quantum efficiency suitable for the reflection-mode (r-mode) GaAs-based photocathode with these two kinds of buffer structures are deduced based on one-dimensional continuity equations, among which the reflectivity changing with the wavelength of incident light is considered in particular. By comparison of spectral characteristics of photocathodes with the two different structures, and analysis of cathode structure parameters, it is found that the photoelectric performance of the photocathodes with the two structures are quite different, and the structure parameters especially the thickness of GaAs emission layer have a great impact on the spectral characteristic. The quantum efficiency of photocathode with graded bandgap structure is improved due to the introduction of the built-in electric field and the decrement of interface recombination, while for cathode with DBR structure, the quantum efficiency is improved by the multiple reflection of light between two parallel mirrors in the stack of alternating quarter-wave layers of high and low refractive. The theoretical quantum efficiency calculation and analysis would provide theoretical guidance for the better design of GaAs-based photocathodes.

In the design of photocathode, the internal electric field could be formed due to the graded Al compositional ${\mathrm{\text{Al}}}_x{\mathrm{\text{Ga}}}_{1-x}\mathrm{\text{As/GaAs}}$ nanostructure, which can improve the top surface emission probability of carriers. In this paper, ${\mathrm{\text{Al}}}_x{\mathrm{\text{Ga}}}_{1-x}\mathrm{\text{As/GaAs}}$ nanostructure array photocathode composed of two sub-layers is presented. Based on the finite element method, the influence of graded geometrical parameters on their optoelectronic characteristics is investigated. The results show that when the thickness of the sublayer is equal, the difference of the Al composition between the two sublayers of nanostructure is larger, the sub-layers are less, and the quantum efficiency is higher. The light capture ability of the photocathode can be enhanced by increasing the thickness and the array spacing of the first sublayer. Compared with the hexagonal cross-section structure, the light trapping effect and spectral response of the circular cross-section structure are better.

A resonance-enhanced GaInAsSb nanopillar array negative electron affinity potential photocathode based on Mie resonance excitation at infrared wavelengths can significantly enhance the absorption and quantum efficiency of nanopillar arrays. Our study indicates the different periodic structures have very little effect on the QE for the nanopillar arrays. However, the smaller the period of the array, the higher the quantum efficiency is achieved, but the probability of being collected by the anode is reduced, so a compromise should be considered in the structure design. Moreover, the incident light inclination and the external electric field can significantly affect the quantum efficiency of the nanopillar arrays. The photocathodes studied here have a quantum efficiency of over 5.7% with an angle of incidence of 30^∘ and an applied electric field intensity of 1.2V/$\mu$m. This work provides an important reference and theoretical basis for the design and optimization of resonance-enhanced GaInAsSb nanopillar arrays photocathode.

The phosphorus doped n-type (n-C:P) carbon films and fabrication of n-C:P/p-Si heterojunction solid-state solar cells by pulsed laser deposition (PLD) technique at room temperature using graphite target have been studied. The P atoms incorporated in the films were determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.22–1.77 atomic percentages. The cells performances have been given in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm², 25°C). The open circuit voltage (V_oc) and short circuit current density (J_sc) for the cells are observed to vary from 215 to 265 mV and from 7.5 to 10.5 mA/cm², respectively. The cell fabricated using the target with the amount of P by 7 weight percentages (Pwt%) shows the highest energy conversion efficiency, η=1.14% and fill factor, FF=41%. In this paper, the dependence of P content on the electrical and optical properties of the deposited n-C:P films and the photovoltaic characteristic of the n-C:P/p-Si cells are reported.

The electroluminescence (EL) studies on the aluminum-doped nanoporous silicon (NPSi:Al) have been conducted. Nanoporous silicon (NPSi) layers have been prepared by anodically etching the unpolished p-type Si[100] wafer with surface resistivity of 4–8 Ω cm^-1 in hydrofluoric solution at 1:1 ratio of ethanol. Aluminum (Al) was doped on NPSi using cathodic electrodeposition composed of aluminum chloride (AlCl₃) and ethanol electrolyte. A diode structure has been fabricated comprising a semi-transparent Au/NPSi:Al/p-Si/Al ohmic contact electrode showing rectification on a forward bias I–V curve. EL from NPSi and NPSi:Al/p-Si has also been observed using the diode structure. The NPSi:Al/p-Si device shows increasing EL quantum efficiency at about 30%, and blue-shift EL spectra are observed. Possible reasons for the enhancement will be discussed.

In this work, a novel ternary Eu (III) metal–organic frame-Eu(cpioa)phen (H3cpioa: 5-(4-carboxy-lphenoxy)-isophthalic, phen: 1,10-phenanthroline monohydrate) was synthesized by a facile hydrothermal method. Structural and optical properties of the binary and ternary Eu (III) MOF were studied in detail. Results show that, compared with the binary Eu(cpioa) MOF, the photoluminescence intensity of the ternary Eu(cpioa)phen MOF is increased by 13.04 times, and the quantum efficiency is increased by 67.2%. The major possible reason for the highly improved photoluminescence properties might be due to the antenna effect induced by the addition of phen. Also, the highly improved crystallinity may also contribute to the greatly increased photoluminescence intensity and quantum efficiency.

The production of Hybrid Photon Detectors to be used as the single-photon sensors for the RICH detectors of the LHCb experiment has recently finished. We present the quantum efficiency measurements of the entire sample of 550 tubes. The manufacturer has succeeded in consistently improving the quantum efficiency of the employed S20-type multi-alkali photocathode above our expectations, by a relative 27 % integrated over the energy spectrum. We also report measurements of the vacuum quality using the photocurrent of the device as a monitor for possible vacuum degradation.

We report on the characterization of candidate light sensors for use in the next-generation Imaging Atmospheric Cherenkov Thlescope project called Cherenkov Thlescope Array, a major astra-particle physics project of about 100 telescopes that is currently in the prototyping phase. Our goal is to develop with the manufacturers the best possible light sensors (highest photon detection efficiency, lowest crosstalk and afterpulsing). The cameras of those telescopes will be based on classical super-bi-alkali Photomultiplier tubes but also Silicon Photomultipliers are candidate light sensors. A full characterisation of selected sensors was done. We are working in close contact with several manufacturers, giving them feedback and suggesting improvements.