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Quantum and classical components are blended together in this proposed theoretical model for describing multiple quantum well solar cells (MQWSC) in a p-i-n architecture. The model characteristics are: the use of transfer matrix as a quantum method for finding allowed energies in the coupled quantum wells, the connection of the absorption coefficient in the confined 2D structure to the one in the bulk semiconductor, and the treatment of the whole cell as a pseudo-homogeneous media to determine its reflectance. The resulted model is intended to be a working tool to assess electro-optical properties of MQWSC. Numerical results which relate the performance of the MQWSC to its structure are reported.

We present a study of the photovoltaic effects of a graphene/n- Si Schottky junction solar cell. The graphene/Si solar cell was prepared by means of rapid chemical vapor deposition, while the graphene films were grown with a CH₄/Ar mixed gas under a constant flow at 950°C and then annealed at 1000°C. It was found that the junction between the graphene film and the n-Si structure played an important role in determining the device performance. An energy conversion efficiency of 2.1% was achieved under an optical illumination of 100 mW. The strong photovoltaic effects of the cell were due to device junction's ability to efficiently generate and separate electron–hole pairs.

Semiconducting thin $\beta$-FeSi₂ film has been recognized as a novel solar cell material due to its high absorption coefficient. In this study, the effects of emitter on the photovoltaic properties of n-$\beta$-FeSi₂/p-Si were analyzed using AFORS-HET program. The simulation results show that the thickness of emitter affects the conversion efficiency of solar cell, and the short-current density decreases sharply with increasing thickness of emitter. Interface state is another key factor influencing the conversion efficiency of solar cell, which degrades solar cell performance. In order to obtain high efficiency battery, interface state density should be less than 10${}^{11}$ cm${}^{-2}$ eV.

Breaking Lorentz reciprocity is one necessary condition of optical isolator design. Unidirectional wavelength-mode conversion will be realized in a time-dependent system through a short operating range. Based on plasma dispersion effect, generate space-asymmetric periodical time-space modulation on silicon waveguide, and non-reciprocal propagation is realized in the waveguide. The designed unidirectional wavelength-mode conversion waveguide demonstrated that in the forward direction, input 1.55 $\mu$m fundamental mode light signal and then output 1.5492 $\mu$m is of 1st-order mode, while in the backward direction, input 1.5492 $\mu$m is of 1st-order mode light signal and then output 1.5484 $\mu$m is of fundamental mode. Based on this non-reciprocal structure, mode conversion waveguide and two-ring resonance filters were designed then, to accomplish on-chip optical isolation. The scale of the designed isolator is 160 $\mu$m × 60 $\mu$m, and the isolation is 21 dB, revealing perfect application potential.

The design proposed and fabricated in this paper is a slotted wide-band rectenna with the inclusion of Defected Ground Structure (DGS) which can harvest RF energy in the frequency range of 5.336–6.194GHz with a center frequency of 5.8GHz. For the development of antenna, FR4 substrate having a dielectric permittivity of 4.3 has been adopted. Two parallel slots on the patch are incorporated on either side of the feed line to obtain the wide-band structure. Dumbbell-shaped DGS is also incorporated exactly underneath the feed line to increase the gain of the antenna. HSMS-285C Schottky diode has been used for the implementation of the rectifier circuit and a Greinacher voltage doubler has been chosen. ADS design software has been used for rectifier simulation and CST has been used for the designing of the antenna. Current behavior on the patch can be investigated to explore the wide-band mechanism. The antenna operates in the frequency range of 5.336–6.194GHz and with VSWR less than 2, which corresponds to 16.07% impedance bandwidth. The antenna achieves a gain of 6.189dB and a directivity of 8.776dBi. The conversion efficiency of the rectifier was optimized to 75% at 5.8GHz. The proposed design gave an output of 3.2V which can be used under numerous energy harvesting and wireless power transmission applications.

Eu³⁺ doped silica films have been prepared by sol–gel method and employed as luminescent down-shifting layer on the front side of a crystalline Si solar cell to improve their conversion efficiency. Measurements under standard test conditions (AM1.5, 100 mW/cm²) show the conversion efficiency of Si solar cell with silica film containing Eu³⁺ is improved 9.5% maximally as compared to the Si solar cell with pure silica film. However, high Eu³⁺ concentration is not encouraged because concentration quenching effect will decrease the efficiency of the solar cell.

In the presented structure, the performance of the all-optical XOR logic gate (AO-XOR-LG) is investigated. The XOR-LG is designed and simulated using a photonic crystal semiconductor optical amplifier (PC-SOA) based on Mach–Zehnder interferometer (MZI) and cross-phase modulation (XPM) nonlinear mechanism. The input optical pulse train used in this simulation is the type of RZ (Return-to-Zero). The finite difference method (FDM) has been used to solve the rate and propagation equations. The effect of input signal energy, bias current, and group refractive index on the output signal and gain of the XOR-LG is studied. The optimal mode is obtained for the XOR-LG with a bit rate of 80 Gbps. Furthermore, for the first time, the effects of quality factor (QF), conversion efficiency (CE), extinction ratio (ER), pattern effect (PE), and gain recovery are simultaneously analyzed in the simulation to increase PC-SOA performance. According to the results, PC-SOA has a more reasonable logic performance than conventional SOA, and due to its much shorter length than SOA, it can be a much better choice for integrated optical circuits.

Quasi-solid-state dye-sensitized solar cells were fabricated using a high molecular polymer redox electrolyte. Poly(ethylene oxide) (PEO) and Poly(vinylidenefluoride-co-hexafluoropropylene) (P(VDF-HFP)) were used to form a stable quasi-solid structure and a three-dimensional gel polymer network structure. The polymer electrolytes were composed of LiI, I₂, and DMPII in the mixture of propylene carbonate (PC) and γ-butyrolactone (GBL) with different volume ratios. A metal-free organic dye (indoline dye D102) was used as a sensitizer. The ionic conductivity of the gel polymer electrolytes was measured with Electrochemical Impedance Spectroscopy (EIS). The dependence of the ionic conductivity on the volume ratio of PC to GBL was investigated. The volume ratio of the mix solvent, weight ratio of PEO/P(VDF-HFP), and the weight ratio of TiO₂ fillers were optimized. The optimized quasi-solid-state cell exhibited an efficiency of 5.49% at full sunlight (air mass 1.5, 60 mW/cm²) irradiation.

ZnO/TiO₂ composite films composed of a ZnO nanoflowers overlayer and a ZnO/TiO₂ composite particulate underlayer were fabricated by a simple hydrothermal process. The as-prepared films were characterized by scanning electron microscopy, transmission electron microscopy (TEM) and diffused reflectance spectroscopy. The performance of dye-sensitized solar cells (DSCs) was investigated by photocurrent–voltage measurements, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy. It was found that the ZnO/TiO₂ composite film prepared with a 60 min growth time exhibited higher reflectivity than that of pure TiO₂ film due to the effective light-scattering of ZnO nanoflowers, resulting in increased J_sc. In the meantime, the open-circuit potential of the device were enhanced from 698 to 826 mV due to the formation of an energy barrier by ZnO at TiO₂/electrolyte interface, resulting in a 52% improvement in the power conversion efficiency from 4.64 to 7.06%.

Organic–inorganic halide perovskites are currently generating extensive interest for applications in solar cells. The perovskite morphology and composition have significant roles in solar cells. Impure phases, which will influence the performance of solar cells, are inevitably present in the film of perovskite. We found that another MAI deposition on the previous perovskite could ameliorate the film. The post-deposited MAI participates in the reconstruction of the perovskite, leading to reduced amount of impure phase, increased grain size, increased absorption and significantly improved power conversion efficiency. The results demonstrate a treatment approach to fabricate efficient planar heterojunction perovskite solar cells.