Absorption Of Thin Films Research Articles

Morphology and structural properties of Sb2(SxSe1-x)3 thin film absorbers for solar cells

Using the thermal evaporation method, thin crystalline films of Sb2(Sx Se1-x)3 are produced at the substrate temperature of 300℃. The mixed powders of the Sb2S3 and Sb2Se3 is used as a source material. The influence of the S/Se component ratio on the morphology and structural characteristics of Sb2(SxSe1-x)3 thin films is investigated. As demonstrated by the results of X-ray energy dispersive spectroscopy, the formed films of Sb2(SxSe1-x)3 have a components ratio close to the stoichiometry. Besides, Morphological and structural analyses reveal significant differences in the surface morphology of Sb2(SxSe1-x)3 thin film absorbers, indicating that the properties of the films vary as a function of the S/Se composition ratio.

Investigation of CuO/ITO Photoelectrode Fabricated by PVD for Efficient Photoelectrochemical Water Splitting and Hydrogen Evolution

ABSTRACTHydrogen and renewable fuels were generated using cost‐effective and efficient electrocatalysts for water splitting. In this work, a CuO‐based photocathode is used for the water splitting to generate hydrogen energy by PVD technique. The XRD analysis reveals the deposition of CuO thin film on ITO substrates, which is monoclinic. The XRD and LSV analysis of CuO confirmed the type of semiconductor and observed to be P‐type semiconductor. SEM study of CuO confirmed the shape, morphology to be a circular and regular shape. The grain size of deposited CuO thin film was found to be 18 nm. The absorption and transmission of CuO thin film were observed through UV spectroscopy analysis and were found to be better photocatalyst in visible range 415–425 nm. The transmittance of the prepared thin film was noted to be maximum 7.6% in the UV range (280–300 nm). The band gap was also measured employing the Tauc plot and found to be 2.98 eV, which is most favorable for water splitting application. FTIR study showed the stretching, vibration, and the functional group of the deposited CuO thin film; the broad band of stretching of Cu‐O in monoclinic CuO was observed at the range of 500–700 cm−1, and further peaks were also noted at the range of 1500–1600 cm−1. The linear sweep voltammetry (LSV) of CuO thin film was calculated in the absence of solar spectra and the presence of solar spectra and observed to be enhanced in current under solar spectra. The solar light to hydrogen emission percentage (STH %) of CuO through LSV was observed to be 2.04% under solar spectra. The low Nyquist curve of blank ITO and CuO‐coated ITO substrate via electrochemical impedance spectroscopy (EIS) analysis was observed, which confirmed the enhancement of EIS of CuO‐coated ITO. The hydrogen generation rate was also calculated by electrochemical cell and observed to be 5325.21 mol g−1 for 6 h.

Broadband Light Harvesting from Scalable Two-Dimensional Semiconductor Multi-Heterostructures.

Broadband absorption in the visible spectrum is essential in optoelectronic applications that involve power conversion such as photovoltaics and photocatalysis. Most ultrathin broadband absorbers use parasitic plasmonic structures that maximize absorption using surface plasmons and/or Fabry-Perot cavities, which limits the weight efficiency of the device. Here, we show the theoretical and experimental realization of an unpatterned/planar semiconductor thin-film absorber based on monolayer transition-metal dichalcogenides. We experimentally demonstrate an average total absorption in the visible range (450-700 nm) of >70% using <4 nm of semiconductor absorbing materials scalable over large areas with vapor phase growth techniques. Our analysis suggests that a power conversion efficiency of 15.54% and a specific power >300 W g-1 may be achieved in a photovoltaic cell based on this metamaterial absorber.

Investigation of thermally induced surface composition and morphology variation of magnetron sputtered Sb2Se3 absorber layer for thin film solar cells

One of the most promising semiconductor materials for the development of sustainable thin-film solar cell technology is antimony selenide (Sb2Se3). Its excellent optical and electrical properties have drawn attention lately for potential application in thin-film solar cells. In this study, Sb2Se3 films deposited using the direct current (DC) magnetron sputtering technique have been subjected to a post-annealing process without an extra selenium supply at temperatures between 150 and 450 °C. Without an extra selenium supply, the impact of post-annealing temperature on the surface composition as well as the physical properties of the fabricated films was investigated. The overall evaluations revealed that the post-annealing temperature is highly efficient in altering the physical properties of the Sb2Se3 absorber thin films. We further observed that the post-annealing process improved the crystallization and the heat treatment temperature quite affected preferential orientation. The surface morphology of films exhibited structural deformation at high post-annealing temperatures (> 350 °C). According to optical and electrical characterizations, respectively, the optical energy gap and the resistivity of Sb2Se3 films reduced with an increment in the post-annealing temperature. Based on the XPS result, the variation in temperature of post-annealing led to a change in the surface composition of the films. The findings on the growth of Sb2Se3 thin films indicate the existence of an intermediate growth temperature that permits the growth of Sb2Se3 films to be optimized. The study’s conclusions can serve as a guide to the growth of Sb2Se3 thin films with the desired crystallinity, surface morphology, and composition for thin film solar cell applications.

Effect of carrier gas on copper antimony sulfide thin films by spray pyrolytic approach

This study explores the ternary compound semiconductor as a potential absorber layer for third-generation solar cells. CuSbS2, a promising candidate for thin film absorber layers, is fabricated using a simple spray pyrolysis method. The research specifically investigates the influence of two different carrier gases during the fabrication process. X-ray diffraction as well as Raman studies confirm that the films exhibit a chalcostibite structure. Notably, films fabricated with nitrogen as the carrier gas demonstrate enhanced crystallinity, accompanied by reduced microstrain and dislocation density. Furthermore, these films exhibit a significantly improved absorption coefficient, reaching 105 cm-1 . Optical studies indicate that the materials possess a direct band gap of 1.50 eV and exhibit p-type conductivity. CuSbS2 thin film heterojunction solar cell exhibits a maximum efficiency of 0.49%.

Over 10% efficient Cu2ZnSn(S, Se)4 Thin-Film cells prepared by aluminium doping

Cu2ZnSn(S,Se)4(CZTSSe) solar cell is of excellent development tendency because of lower pollution and outstanding power conversion efficiency(PCE). Yet, current PCE of CZTSSe is limited because of a high open-circuit voltage deficit, primarily put down to severe band tailing and carrier recombination. In this paper, absorber films were obtained by solution method and the influences of different aluminum doping concentrations on the properties of CZTSSe thin film cell were studied. Analysis about X-ray diffraction (XRD) and Raman spectroscopy confirms which Al has incorporated into CZTSSe thin film lattice and replaced Sn. Hall effect measurements reveal the improvement of carrier concentration on thin film absorber layer attribute to the formation of AlSn acceptor defects. Furthermore, X-ray photoelectron spectroscopy (XPS) reveals that Al enter into the CZTSSe lattice and Al is in the appropriate state of + 3 valence without generating additional harmful defects. More important, the generation of deep energy level defects and defect clusters associated with Sn were suppressed by replacing Sn with Al. Finally, the photovoltaic performance of different Al doped CZTSSe cells were characterized by conducting J-V and external quantum efficiency (EQE) tests. Remarkably, the CZTSSe solar cell with PCE as high as 10.59 % is obtained under a doping level of 6 % Al, which has an open circuit voltage of 522 mv. Compared with reference CZTSSe solar cells with an efficiency of 7.29 %, which indicates with improvement of 45 % in efficiency. Consequently, Al doping process is considered as a prospective tactic to elevate the PCE of CZTSSe solar cells.

On the performance of a Q-switched erbium-doped fiber laser based on a cadmium-sulfide (CdS) thin-film saturable absorber

On the performance of a Q-switched erbium-doped fiber laser based on a cadmium-sulfide (CdS) thin-film saturable absorber

Thin film resonant metasurface absorbers using patch-based arrays on liquid crystal polymer substrates for centimeter-wave applications

This paper reports the design and development of thin-film resonant absorbers for narrowband and multiband operation in the frequency regions centered at 10 GHz. The structure of the resonant metasurface absorber (RMA) is based on a liquid crystal polymer (LCP) thin-film spacer with a copper patch array on the front surface and un-patterned copper film on the back surface of the LCP film. The design and simulation works were carried out using full-wave analysis of the RMA characteristics. The copper-based periodic patch array acts as a metasurface. The perfect RMA for a given LCP film thickness can be obtained through impedance optimization by adjustment of the dimensions of the lattice periods. The electric and magnetic field distributions were studied. The resonant film absorber based on a 100 μm thick LCP film has an electrical thickness of λ/300 at 10 GHz. The experimental work was conducted using a narrowband RMA prototype consisting of 11×11 cells. The measured result of the resonant absorption is at 10.1 GHz, which is in close agreement with the design frequency of 10 GHz. For multiband functionality, double- and quad-band film resonant absorbers have been designed based on a coplanar supercell utilizing the superposition of the resonance effect. The LCP film-based absorbers have the potential to be used in EM shielding and sensing applications in centimeter-wave applications.

Enhanced microwave absorption and mechanical performance of polyvinylidene fluoride thin films embedded with novel activated carbon and manganese ferrite

AbstractThin composite films hold great promise for microwave devices for microwave absorption. This work mainly focuses on the investigation of the microwave absorption and mechanical studies of a composite thin film of activated carbon and manganese ferrite as conductive fillers within a polyvinylidene fluoride (PVDF) matrix. The production of activated carbon was successfully accomplished using a pyrolysis technique. Composite films consisting of polyvinylidene fluoride (PVDF) and activated carbon‐manganese ferrite were fabricated using a solution blending method. The composite films maintained a consistent concentration of activated carbon at 5 wt%. The characterization of the materials was conducted using scanning electron microscopy and X‐ray diffraction. The composite consists of 3 wt% of MnFe2O4 and 5 wt% Activated carbon/PVDF showed exceptional absorption properties and achieved a minimum reflection loss of around −38 dB at a frequency of 8–12 GHz at a thickness of 2 mm. Significantly, the composite film exhibited a greater tensile strength than the PVDF film. The results of our study highlighted the enhanced microwave absorption and economical manufacturing technique for producing composite films. These films exhibit promising microwave‐absorbing properties in stealth applications.Highlights A facile strategy to fabricate thin film PVDF composites was proposed. Novel activated carbon was synthesized to enhance the conductivity. Achieved reflection loss of around −38 dB at a frequency of 8–12 GHz. Synergistic effects of fillers enhanced dielectric and magnetic losses. Exhibited efficient mechanical performance and microwave absorption.

Enhanced microwave and far IR absorption of nanometer thin conductive films in the case of total internal reflection

Enhanced microwave and far IR absorption of nanometer thin conductive films in the case of total internal reflection

Light-absorber engineering induced defect passivation for efficient antimony triselenide solar cells

Antimony selenide (Sb2Se3) has attracted considerable attention thanks to non-toxic, earth-abundant and exceptional optoelectrical properties. Post-selenization treatment is a widely used approach to improve crystallization and passivate defects for chalcogenide thin-film solar cells. The overall performance of the final device is often significantly affected by the process conditions. Herein, we have systematically explored the influence of selenization pressure on Sb2Se3 thin-film solar cells fabricated via sputtering and post-selenization. High-quality Sb2Se3 thin films without visible voids and blisters have been obtained at an optimized selenization pressure of 0.05 Pa. The optimized Sb2Se3 absorber thin film not only mitigates charge carrier recombination but optimizes the back contact of the device. Consequently, a remarkable efficiency of 7.42 % was obtained for the champion device, paving a simple and effective way to fabricate superior Sb2Se3 absorber thin films and highly efficient solar cells. This study is expected to give insights into post-selenization operating conditions for device efficiency enhancement and to further expand the commercial application of Sb2Se3 thin-film solar cells.

Realization of CO2 gas sensors and broadband photodetectors using metal/high-k CeO2/p-Si heterojunction

Realization of high-k dielectric oxide material-based devices such as photodetectors (PDs)/gas sensors fabricated on silicon substrate seems to be the utmost promising as a cost-effective approach to use in next generation optoelectronic field. We have explored metal/CeO2/p-Si heterojunction to construct as a broadband (BB) PD and CO2 gas sensor device. The effect of post-annealing procedure on photodetection and CO2 gas sensing characteristics were correlated using AFM, XRD, XPS, Raman and UV–Vis studies. At 0 V bias, the fabricated as-deposited Au/CeO2/p-Si PD device exhibits outstanding performance with enhanced responsivity of 85 AW−1 (at 910 nm), detectivity of 1.36×1015 Jones (at 850 nm), EQE of 1.3×104 % (at 850 nm), faster rise and fall times of 124 ms and 107 ms (at 900 nm). On the other hand, the photodetection characteristic parameters were slightly deteriorated as a function of annealing with respect to the as-deposited device. One of the causes for this fact was attributed to the increase in rms surface roughness (AFM) and decrease in absorbance of CeO2 thin film (UV–Vis). Additionally, Ag/CeO2/p-Si heterojunction was studied as a CO2 gas sensor and evaluated response/recovery times as a function of CO2 gas concentration. Sensing responses of CeO2 as-deposited, CeO2-400, CeO2-500, CeO2-600 and CeO2-700 °C were around 58, 60, 62, 81 and 90 %, respectively, when exposed to 200 ppm of CO2. Thus, we validate that the prospect of integrating enhanced performance in BB PDs and CO2 gas sensors using metal/CeO2/p-Si heterojunction could serve as a basic building block in near future optoelectronic applications. Furthermore, the effect of post-annealing temperature on the morphological, structural, BB photodetection and CO2 gas sensing properties were discussed in detail.

Dual solution synthesis of Al doped CuS thin films for optoelectronic and photovoltaic applications

Dual Solution Synthesis (DSS) was used to deposit CuS doped with Al. The Samples were subjected to annealing under varying temperatures of 319K and 373K . The thin films were firmly adherent to the substrates. The optical properties were measured using UV -1800 series double beam spectrophotometer. The transmittance is from 0.3% to 0.6% while the reflectance is between 0.176 to 0.204, as the wavelength ranges from 320nm to 1000nm; the average band gap obtained is 2.6. The thicknesses achieved are 100nm and 124 nm. Other Optical properties were determined for each sample which makes it suitable for applications in optoelectronic, solar energy conversions, solar cells, thin film absorbers, anti- reflective coating, aesthetic windows, UV filter and other uses.

Examination of structural and spectrophotometric optical characteristics of nano-like flower quinolinyl carbonyl pyrazole-1-carbodithioate films: a new trend for optoelectronic applications

The current investigation entailed the synthesis of benzyl 5-amino-4-[(1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)carbonyl]-1H-pyrazole-1-carbodithioate (referred as BAEHQP, compound 2) from 6-ethyl-4,5-dioxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile (compound 1), followed by its characterization in nanocrystalline thin films produced through thermal evaporation in a high vacuum. Computational and experimental methodologies were employed for this purpose. Density functional theory (DFT) calculations using the B3LYP/6-311++G(d,p) basis set were utilized to predict the HOMO-LUMO gap and evaluate the global reactivity descriptors, elucidating the chemical hardness, kinetic stability, and electron-donating capabilities. X-ray diffraction (XRD) analysis verified the presence of a polycrystalline structure in the BAEHQP powder and indicated an amorphous nature in the thin film. Utilizing the Williamson-Hall formula, the mean crystallite size and microstrain were determined to be 63.36 nm and 0.00667, respectively. Scanning electron microscopy corroborated the nanoflower-like structure, and particle size analysis was conducted to determine the size distribution. The optical properties, encompassing both linear and nonlinear aspects, of BAEHQP thin film were investigated using spectrophotometric methods, delineating band transitions and identifying a fundamental direct energy gap of 2.2 eV. The distinct attributes of thin-film absorption and dispersion were outlined, and the unanticipated findings hold potential implications for advancing the industrialization of photodiode device manufacturing.

Large nonlinear optical absorption and refraction of β-In2Se3 thin film from above to below bandgap excitation

Nonlinear optical materials, especially two-dimensional materials, are anticipated to reveal broadband optical nonlinearity for future miniaturized photonic applications. Herein, we report a physical vapor deposition method to produce β-In2Se3 thin film and investigate the broadband nonlinear absorption (β) and refraction (n2) characteristics. The β-In2Se3 semiconductor shows an excellent optical nonlinearity with large β in 102 cm GW−1 scale and n2 in 10−12 cm2 W−1 scale from visible to NIR wavelengths, which are superior to those of metal carbides and nitrides (MXenes) and metal-organic frameworks. This excellent optical nonlinearity makes β-In2Se3 a promising candidate for advanced nanophotonic devices and beyond.

Influence of Stacking Order on the Structural and Optical Properties of Cu2ZnSnS4 Absorber Layer Prepared from DC-Sputtered Oxygenated Precursors

Several studies have attempted to overcome the sudden volume expansion of the precursor during sulfurization by the use of oxygen-containing precursors when growing the CZTS absorber. This work demonstrates the influence of precursor stacking orders on the properties of the CZTS thin film absorber layer from DC-sputtered oxygenated precursors for solar cell applications. CZTS absorber layers were prepared from three types of DC-sputtered stacks, namely, Zn-O/Sn/Cu, Sn/Zn-O/Cu, and Sn/Cu/Zn-O. The precursors were sequentially deposited on a soda lime glass (SLG) using DC-magnetron sputtering and annealed in a sulfur and nitrogen ambient. X-ray diffractometry (XRD) and Raman spectroscopy analyses reveal the formation of crystalline kesterite CZTS structure regardless of the precursor stacking order. Atomic force microscope (AFM) analysis showed that CZTS thin films grown from precursor stacks SLG/Zn-O/Sn/Cu and SLG/Sn/Zn-O/Cu had improved morphological properties with densely packed large grains compared to that with stack SLG/Sn/Cu/Zn-O. SLG/Zn-O/Sn/Cu is the best stack among the studied stacking orders since it exhibits large grains in the absorber layer, which is preferential for high-efficiency thin film solar cells. The use of oxygenated precursor with order Sn/Zn-O/Cu promises improved CZTS absorber properties as it exhibits better morphological properties.

Synthesis and characterization of CZTS and Cu2-xAgxZnSnS4 thin films for the application of solar cells

We report on colloidal Cu2ZnSnS4 (CZTS) and Cu2-xAgxZnSnS4 (X=0.25) nanoparticles synthesis by sol-gel spin coating process and hot injection method. The colloidal nanoparticles were deposited on ITO substrates by using spin-coating techniques. The deposited thin films were characterized by X-ray diffraction (XRD), UV-visible spectrometer, FE-SEM, Raman spectroscopy and Keithley 2450 Source meter. XRD reveals that the crystal structure of CZTS is confirmed tetragonal structure with peak (112) and observed the changes to wurtzite peak (002) due to the presence of Ag. UV visible spectra show that the optical band gap of CZTS nanoparticles decreases from 2 eV to around 1.75 eV, and there is a significant improvement in absorption coefficient when the sample is prepared under a nitrogen atmosphere. FESEM captured the microstructure image of CZTS and Cu2-xAgxZnSnS4. Photoluminescence (PL) reveals the emission peaks and Raman spectra investigate the secondary phases present. XPS confirms the presence of each element and their oxidation state. Further, electrical properties are studied using the four-probe method at room temperature. CZTS offers optical and electrical properties, which allow it to be suitable for thin-film solar cell absorber layers, and Ag doping enhances its properties.

A theoretical study on optical field distribution and absorption of stacked thin films supported by a reflective back layer

The stacked thin films have recently been of great interest for enhancing the optical and thermal absorption of the system via their specific optical properties depending on the optical wavelength and layer thickness. Here, by using Maxwell’s equation for the electromagnetic fields penetrating thin films, we simulated in detail the absorption of the nanometer-thick thin film of several materials, such as Au, Ag, Cu, and Al, and figured out the optimal thickness range for the outer layers exposed to incoming field to optimize the energy harvesting. In particular, the absorption of the film supported by a totally reflective layer at the back of the structure could be significantly enhanced, and the maximal absorption happens at a layer much thinner than that in the case of the film solely irradiated by the field. These results could help suitably choosing of detailed thickness for the structure to optimize the field effect on a specific layer.

Numerical investigation of CuSbS2 thin film solar cell using SCAPS-1D: enhancement of efficiency on experimental films by defect studies

The study of photovoltaic solar cells has been an exciting field of research because of their environmentally friendly nature. Scientists are continuously searching for new methods to develop solar cells that are highly efficient and cost-effective. One promising option is the use of Copper Antimony Sulphide (CuSbS2) based ternary compound semiconductor in ultrathin film photovoltaic cells. This material has a high absorption coefficient, low cost, and is readily available in the earth’s crust. These characteristics make it an ideal candidate for use as a thin-film absorber layer in solar cells. In this work, FTO/CdS/In2S3/CuSbS2/Spiro-OMeTAD/Au device is proposed to improve the efficiency of experimentally designed CuSbS2-based thin film solar cells using numerical modeling. Device simulation was carried out using SCAPS-1D software, and the illumination spectrum used for this optimization was 1.5 AM. The simulated results from SCAPS-1D were compared to the experimental data. After optimizing the device parameters all the electrical parameters of the solar cell were improved. The optimized CuSbS2-based device shows power conversion efficiency (PCE) of 21.11% with short circuit current density (Jsc) of 20.96 mA cm−2, open circuit voltage (Voc) of 1.23 V, and fill factor (FF) of 81.84%. Based on the simulation results, it is possible to increase the performance of the device by varying different parameters such as the defect density of each layer, interfacial defect density, thickness, and doping concentration.

Investigation of the third-order optical nonlinear enhancement properties of Ag doped chalcogenide glass films

Chalcogenide glass is widely recognized as an excellent nonlinear optical material. Enhancing its nonlinear optical properties through metal doping has emerged as a prominent research avenue in the field of chalcogenide glass. In this paper, silver (Ag) doped Ge28Sb12Se60 (GSS) chalcogenide glass films with different concentrations were prepared by co-evaporation method. The nonlinear absorption coefficients (β) of different samples were investigated by open-aperture top-hat Z-scan experiments and pump-probe experiments, and the nonlinear refractive index (γ) values were determined using the Tichy-Ticha relation. The results showed that the nonlinear absorption of GSS thin films can be improved by Ag doping. The nonlinear absorption coefficient β exhibits the maximum enhancement of about 2.5 times at 8.3% concentration, with the maximum β reaching 1.83×10−6 m/W. The nonlinear absorption mechanism observed in the thin films can be attributed to free carrier absorption, and the free carrier lifetime is positively correlated with the Ag doping concentration. Within the selected Ag concentration range, the nonlinear refractive index (γ) of Ag doped chalcogenide glass films continues to increase, reaching about 3 times at 30.7% concentration, with the maximum γ being 4.643×10−17 m2/W. Additionally, the third-order nonlinear polarizability (χ(3)) values can be increased from 1.014×10−11 esu to 3.314×10−11 esu with increasing Ag concentration. The research results in present paper are of great significance for further exploration of the optical nonlinear enhancement properties and carrier recombination dynamics in chalcogenide glass.