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The lead-free halide double perovskite material A₂BB’X₆ represented by Cs₂AgBiBr₆, has higher potential as a photovoltaic material since it has good electronic and optical properties in recent years. However, the highest power conversion efficiency (PCE) achieved for solar cells made with Cs₂AgBiBr₆ as the light-absorbing layer in experiments is only 2.51%. To investigate this phenomenon, we used the Solar Cell Capacitance Simulator (SCAPS) simulation software to build five solar cell models with the structure of FTO/ZnO/Light-absorbing layer/Cu₂O/Au based on different light-absorption layer materials. Two reasons causing the low PCE of Cs₂AgBiBr₆ solar cells were identified. On the one hand, interlayer defects in Cs₂AgBiBr₆ film synthesis significantly decreased the fill factor (FF), thereby reducing the quantum efficiency (QE). On the other hand, Cs₂AgBiBr₆’s larger indirect bandgap resulted in a narrower absorption range. Additionally, it was demonstrated that adjusting the material thickness and alloying method could, respectively, improve the two aforementioned issues. When the thickness of the light-absorbing layer material was 300nm, the FF increased from 39.88% to 55.01%, resulting in an optimal PCE of 3.88% for the solar cell. Alloying increased the short-circuit current ($J_{\mathrm{\text{SC}}}$) from 8.44mA/cm² to 21.24mA/cm², leading to a simulated PCE increase of 8.92% for solar cells based on Cs₂NaSb${}_{0.5}$In${}_{0.5}$I₆. This work, from the perspective of device simulation, is highly significant for improving the photoelectric conversion efficiency of Cs₂AgBiBr₆-based perovskite solar cells in experimental settings. It offers new insights for optimizing solar cell efficiency.

The hazards of prevailing global warming on this planet have forced human beings to utilize clean energy substitutes. None of the clean energy sources could be better than the Sun. To exploit solar energy to the maximum extent, solar cells were invented. However, the solar cells ruling today’s world are all made from inorganic materials which are not only expensive but also involve complex fabrication processes. Additionally, these cells are limited to utilization on rooftops only. To overcome this scenario organic solar cells are the reliable contender to inorganic solar cells. A review of the origin and developments regarding organic solar cells is explained in this paper, and the improvement in the efficiency of a suggested organic solar cell with optimization at 800nm is 24.05%.

For quite a long time, the scientific community has been searching for a material that surpasses the existing material systems in terms of energy conversion efficiency for photovoltaic applications. In this study, the optoelectronic properties of pure and Al-doped boron arsenide B${{}_{1-}}_x$Al${}_x$As $(x=0,0.125\mathrm{\text{and}}0.25)$ in the zinc blende (ZB) structure were systematically examined using the density functional theory (DFT) and the Modified Becke–Johnson (TB-mBJ) exchange correlation (XC) potential. The Perdew–Burke–Ernzerhof generalized gradient approximation (PBE) functional was used for structural optimization. After considering the ground state lattice constant of 4.82Å then calculating the bandgap energy of pure BAs, which are consistent with experimental and theoretical findings, we estimated the basic electronic and optical characteristics of Al-doped boron arsenide, including band structures, electronic density of state, dielectric function, refractive index, extinction coefficient, absorption and optical conductivity. The unusual and interesting optoelectronic features of the investigated compounds revealed in this work offer substantial promise for improving the energy conversion efficiency of solar cells.

In this paper, we reported highly conductive p-type microcrystalline silicon (μc-Si:H) films deposited on amorphous silicon (a-Si:H) surface by very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) technique. Hydrogen plasma treatment of amorphous silicon surface and nucleation layers were introduced prior to μc-Si:H films deposition. The film properties were investigated by using Raman spectra, scanning electron microscope (SEM), optical transmission and reflection, as well as dark conductivity measurements. The influence of plasma treatment and nucleation layer on the growth and properties of the thin p-type μc-Si:H films was studied. It is demonstrated that the hydrogen plasma treatment of a-Si:H films gives rise to the deposition of μc-Si:H on the a-Si:H surface. Also, the growth and properties of the μc-Si:H films are strongly dependent on the nucleation layer. The dark conductivity (σ_d) and crystalline fraction increase with the plasma treatment time and attain high values at about 600 s. A p-type μc-Si:H film with conductivity of 0.0875 Scm^-1 at a thickness of 30 nm was obtained. The film was introduced as window layers for flexible solar cells. An efficiency of about 7.15% was obtained.

In this study, single-kesterite-phase Cu₂ZnSnS₄ (CZTS) and Cu₂ZnSnSe₄ (CZTSe) nanocrystallines have been synthesized by a simple solvothermal route. Scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorbance and Raman scattering spectroscopy were used to characterize the optical and micro-structure properties of the as-synthesized samples. The bandgap of CZTS could be tuned in a large range by incorporating a few Se atoms. Both the CZTS and CZTSe exhibited the similar temperature dependence of the Raman "A" modes, including a monotonic redshift in peak position and an irregular variation in peak linewidth. Such a behavior might be due to the cumulative effect of thermal expansion and small crystalline sizes.

The purpose of the study is to characterize and improve the fundamental understanding of the effects of Ethyl Cellulose (EC) binder on the rheological properties of silver pastes for screen printing front electrode films of solar cells. Dispersions of silver particles (surface modified with oleic acid) in EC polymer solutions with and without thixotropic agent were prepared; and yield stress values were measured by setting shear stress to characterize the strength of interaction in pastes. Week flocculation network of silver particles is produced due to depletion of flocculation. EC polymer also has a significant interaction with thixotropic agent. Down-sweep flow curves of dispersions without thixotropic agent were measured and well fitted by Generalized Casson model. The model parameters p indicated that EC polymer with high molecular weight has a stronger shear-thinning ability. Steady-state flow, three interval thixotropy shear test (3ITT) and oscillatory measurements were conducted to study the effect of EC content on viscosity, structure rebuilding and viscoelastic properties of electrode pastes. Increasing EC polymer is not the best way to prevent the layer printed from laying down.

The ${\mathrm{\text{Cu}}}_2{\mathrm{\text{ZnSnS}}}_4$, ${\mathrm{\text{Cu}}}_2{\mathrm{\text{ZnSnSe}}}_4$ and ${\mathrm{\text{Cu}}}_2{\mathrm{\text{ZnSnTe}}}_4$ and their alloys have been frequently investigated experimentally owing to their suitable bandgap for the solar cell applications. For the first time, density functional theory is applied to explore the structural, electronic and optical properties of ${\mathrm{\text{Cu}}}_2\mathrm{\text{ZnSn}}({\mathrm{\text{S}}}_{1-x}{\mathrm{\text{Te}}}_x)$ and ${\mathrm{\text{Cu}}}_2\mathrm{\text{ZnSn}}({\mathrm{\text{Se}}}_{1-x}{\mathrm{\text{Te}}}_x)$$(x=0,0.25,0.5,0.75,1)$. The energy minimization procedure reveals that the Kesterite phase is stable compared to the Stannite structure. Lattice constants of the compounds are in good agreement with the previous experimental results. The alloys have direct bandgaps which decrease by increasing the concentration of Te. The chemical bonding among the cations and anion is dominantly covalent. Electronic bandgap dependent optical properties like absorption coefficient and optical conductivity are studied in detail. The materials show strong response in the visible region of energy spectrum indicating the usefulness of these materials for optoelectronic devices.

In this work, spatially resolved characterization methods are used to identify loss mechanisms for common $p$-type silicon solar cell architectures, including multicrystalline aluminum back surface field (Al-BSF), monocrystalline Al-BSF, monocrystalline passivated emitter and rear cells (PERC), and bifacial monocrystalline PERC. The characterization methods used in this work include suns-$V_{\mathrm{\text{OC}}}$, photoluminescence imaging, and spatially resolved external quantum efficiency and reflectance measurements. The optical and recombination losses are driven by the material properties, cell processing conditions, and device architecture. These losses are quantified and categorized in terms of underlying mechanisms (e.g., front reflectance, escape reflectance, front recombination, and parasitic optical absorption and recombination in the bulk and rear). The ability to create images of these loss parameters can be used to gain more insight into the materials and manufacturing processes used to produce solar cells, and examples are given in this work to illustrate how these images can help reveal the origin of defects.

MoSe₂ from monolayer to bulk phase can realize the transition from a direct bandgap semiconductor to an indirect bandgap semiconductor. Its bandgap varies between 1.1 and 1.55 eV, which matches the solar spectral range, so Si-based heterojunction solar cells with MoSe₂ as an active layer have great significance in the development of low-cost, high-efficiency and high-flexibility photovoltaic devices. In this work, MoSe₂ thin films were synthesized by chemical vapor deposition using MoO₃ and Se powders as precursor sources. The effects of different process parameters (Se source temperature, Mo source temperature, growth time, carrier gas flow rate and hydrogen ratio) on the synthesis of MoSe₂ thin films were systematically investigated. The optimized experimental parameters were determined as follows: the molybdenum source temperature of 800${}^{\circ }\mathrm{\text{C}}$, the selenium source 20 cm away from molybdenum source, the growth time of 10 min, the carrier gas flow rate of 60 sccm, the hydrogen ratio of 10%. Then MoSe₂/Si heterojunction solar cells were constructed via wet chemical transfer. The open-circuit voltage, short-circuit current density, filling factor and photovoltaic conversion efficiency of the fabricated solar cells were 0.19 V, 5.71 mA/cm², 30.47% and 0.33%, respectively. Main factors affecting the photovoltaic performance of the MoSe₂/Si solar cells have also been discussed. This work is very helpful for the development of MoSe₂ material and relevant application in the field of solar cells.

Perovskite solar cells (PSCs) without hole transport layer (HTL) based on organic and inorganic metal halide perovskite have received vast consideration in recent years. For predigestion of device structure and construction process, the exclusion of the HTL is a marvelous way. By detaching the HTL part of the devices, we could reduce the cost and complexity of the structures. Currently, a novel 2D material named Ti₃C₂ MXene with high electron mobility, excellent metallic conductivity and functionalized surface groups applied for tuning the energy offsets has been reported to be added in the perovskite absorber layer, leading to a remarkable power conversion efficiency (PCE) improvement. In this work, the role of MXenes in controlling the work function of the involved layers to modify the band alignment towards better performance of the cells is explained. Two HTL free structures of FTO/mTiO₂/cTiO₂/MAPbI₃/Spiro-OMeTAD/Au named as HFRC, and FTO/mTiO₂+MXene/cTiO₂+MXene/MXene/MAPbI₃+MXene/Spiro-OMeTAD/Au named as HFMC were simulated by SCAPS-1D software to study the response of the photovoltaic devices and obtain the highest possible efficiency considering the physics behind. To the best of our knowledge, this is the first time such structures and the results of the current simulation are studied that may be used as a guideline for other practical purposes. We present a modeling procedure that optimizes the thickness of the involved layers and specifies the optimum level of the doping concentration. We also show that by optimizing the work function of the back contact, the device performance witnesses a significant improvement, proving the considerable role of the back contact in these cells. The simulated HTL-free devices illustrate attainably PCEs of about 20.32% and 21.04% for the cells without and with MXene, under AM 1.5G illumination and absorption up to 760 (nm).

A series of undoped and p-doped a-SiC:H samples have been made in the framework of a research plan for obtaining high quality p-type window layers by "Plasma Enhanced Chemical Vapor Deposition (PECVD)" technique from the mixtures of silane (SiH₄), methane (CH₄) and diborane (B₂H₆) gases. For the optimization of the window layer, the dependence of the electrical (conductivity) and optical (band gap) properties due to altered ratios of methane and diborane gases were investigated. When the diborane gas ratio was changed from Y = 0.06 to Y = 0.24 with an increase of 0.06 steps at a constant of X = 0.948 methane gas ratio, the dark conductivity and optical band gap values changed from ~ 10^-19 (Ω·cm)^-1 to ~ 10^-10 (Ω·cm)^-1 and 2.542 eV to 2.178 eV, respectively, and between these values, the most appropriate layers can be selected.

In this paper, optical absorptions in silicon nanowires (SiNWs) arrays obtained from theoretical studies and experimental approaches have been reviewed. A brief description on the different growth techniques for SiNW arrays reported so far is presented. Comparative analysis based on major research findings has been done and the advantages of SiNW-based solar cells over thin film solar cells are presented. Furthermore, future aspects of the use of SiNWs for photovoltaic applications are discussed.

Briefly, we reviewed the latest progress in energy conversion efficiency and degradation rate of the quantum dot (QD) solar cells. QDs are zero dimension nanoparticles with tunable size and accordingly tunable band gap. The maximum performance of the most advanced QD solar cells was reported to be around 10%. Nevertheless, majority of research groups do not investigate the stability of such devices. QDs are cheaper replacements for silicon or other thin film materials with a great potential to significantly increase the photon conversion efficiency via two ways: (i) creating multiple excitons by absorbing a single hot photon, and (ii) formation of intermediate bands (IBs) in the band gap of the background semiconductor that enables the absorption of low energy photons (two-step absorption of sub-band gap photons). Apart from low conversion efficiency, QD solar cells also suffer from instability under real operation and stress conditions. Strain, dislocations and variation in size of the dots (under pressure of the other layers) are the main degradation resources. While some new materials (i.e. perovskites) showed an acceptable high performance, the QD devices are still inefficient with an almost medium rate of 4% (2010) to 10% (2015).

This work presents the results of synthesis and characterization of polycrystalline $n$-type Bi₂S₃ thin films. The films were grown through a chemical reaction from co-evaporation of their precursor elements in a soda-lime glass substrate. The effect of the experimental conditions on the optical, morphological structural properties, the growth rate, and the electrical conductivity $(\sigma )$ was studied through spectral transmittance, X-ray diffraction (XRD), atomic force microscopy (AFM) and $\sigma$ versus $T$ measurements, respectively. The results showed that the films grow only in the orthorhombic Bi₂S₃ bismuthinite phase. It was also found that the Bi₂S₃ films present an energy band gap $(E_g)$ of about 1.38 eV. In addition to these results, the electrical conductivity of the Bi₂S₃ films was affected by both the transport of free carriers in extended states of the conduction band and for variable range hopping transport mechanisms, each one predominating in a different temperature range.

Low-reflection polyethylene terephthalate (PET) films are fabricated with nano-imprinting method. The films are then used to cover polycrystalline silicon solar cells. The morphological and optical properties of films are investigated. The films have periodic cylinder-like nanostructures and relatively low reflectivity in light incident angle ranging from 30${}^{\circ }$ to 60${}^{\circ }$. The nanostructures are with a period of 600 nm and height of 90 nm. Besides, the polycrystalline Si solar cells covered with the films exhibit 12% more power generation than the cells covered with glass. Nano-imprinting method offers a cost-effective approach to fabricate omnidirectional anti-reflection films, which could boost the power generation of Si solar cells. Additionally, the films also have potential applications in different types of solar cells due to its facile fabricating process.

This paper tackles anti-reflection coating structure for silicon solar cell where conductive nanoparticle (CNP) film is sandwiched between a semi-infinite glass cover and a semi-infinite silicon substrate. The transmission and reflection coefficients are derived by the transfer matrix method and simulated for values of unit cell sizes, gab widths in visible and near-infrared radiation. We also illustrated the dependence of the absorption, transmission and reflection coefficients on several angles of incidence of the transverse magnetic polarized (TM) waves. We found out that reflection decreases by the increase of incident angle to 50${}^{\circ }$. If nanoparticles are suitably located and sized at gab width of 3.5 nm, unit cell of 250 nm and CNP layer thickness of 150 nm, the absorptivity of the structure achieves 100%.

This paper reports a high-efficiency approach to improve the photoelectric-conversion efficiency of thin-film solar cells by plasmonic scattering and local near-field amplification of silver nanoparticles. We employ a three-dimensional (3D) electromagnetic model and use the finite-difference time-domain (FDTD) and rigorously coupled-wave analysis methods to investigate the interaction of light with such a metallic particle. The numerical results show that the absorption and scattering spectra depend upon the properties of the embedded particles and the refractive index of the surrounding material. Strong redshifts and high-order modes are observed in the response spectrum with the increase of the particle size and the refractive index of the surrounding material. With an optimized design having $P=200$, $H=135$, and $D=70$ nm, the performance of cell device is improved over a broad spectral range. Moreover, some of the absorption, in the resonance region, is beyond the Yablonovitch limit. The corresponding light-generated photocurrent is increased from 14.2 mA/cm² to 18.3 mA/cm², with a 28.9% enhancement compared with conventional cells with antireflective coatings (ARCs).

New artificial Negative index materials (NIMs) or metamaterials have rapidly attracted researchers and industry due to their unusual properties. Applications of various NIMs have been found to be used in manufacturing and design some nano devices such as optical sensors and solar cells. The concept of solar cells depends on the maximizing the light transmission and minimizing the reflection. We propose solar cell structure model based on NIMs to enhance the light efficiency in solar cells. The proposed structure consists of four layers including two NIMs layers called Double NIMs. The simulation of the proposed model has been done utilizing the Transfer Matrix Method (TMM). High transmission and low reflection have been obtained. Solar cells based on double NIMs show promising future and could successfully be used to design highly efficient solar cells.

Using the Wien2k code based on Full Potential Linearized Augmented Plane Wave approach, the density functional theory was used to examine the structural and opto-electronic properties of CuO. The 4D-optimize option and the Perdew–Burke–Ernzerhof (PBE)-sol functional are used to optimize the structural parameters. Generalized Gradient Approximation (GGA) with PBE-scheme along with the screened Coulomb interaction $(\mathrm{\text{GGA}}+U)$ and modified Becke–Johnson (GGA–TB-mBJ) potential was performed for the overall calculations. The computed band energies were taken as the key input to extract the transport properties with the help of the Boltzmann transport equation. In contrast to the gap energy provided by the $\mathrm{\text{GGA}}+U$ ($E_g=1.57$eV), it is demonstrated that the gap energy produced by the TB-mBJ is $\sim 2.02$eV, which is close to the experimental data. The optical characteristics show a high absorption coefficient in the ultraviolet region, an average transmittance of about 65% in the visible range, which covers a wide spectrum of light, and an average reflectance of about 18% in visible light. At low temperatures, the carrier mobility limits the CuO conductivity, whereas, at high temperatures, the carrier concentration dominates. CuO is a potential material for solar cell applications as an absorbent layer and antireflection coating due to these characteristics.

Strain engineering is generally employed as an efficient means of tuning the physical properties of a target compound. In this research paper, we investigated the effect of three axial stretches on the structural, electronic, optical, and thermoelectric properties of inorganic Ge-based halide perovskites LiGeBr₃. Computations were carried out using Density Functional Theory (DFT) and the semi-classical Boltzmann transport theories. The electronic investigation indicated that LiGeBr₃ perovskite exhibits a direct bandgap of 0.480eV. The findings suggest that the bandgap is highly responsive to strain, which improves the absorption ability in the visible light range (300–500nm). The relative stability of the strained compounds and the feasibility of their synthesis were robustly demonstrated by the negative formation energies. The transport features were assessed as a function of temperature and yielded interesting results. The electrical conductivity was considerably enhanced under strain, and the highest figure of merit was found at low temperatures (approximately 0.741). Our theoretical discovery proved that strain is an enormously exciting technique for extending semiconductor applications and boosting thermoelectric and solar cell devices.