The electron transport layer (ETL) is critical in perovskite solar cells (PSCs) as it controls the optics of the complete solar cell. This study uses an industrially viable RF magnetron sputtering ...technique to prepare the tungsten oxide (WO
x
) ETL for PSCs. Necessary morphological and optoelectronic investigations were carried out to ensure the high-quality WO
x
thin-film. The influence of the deposition power on the ETL thickness and PSC optics were systematically investigated. A three-dimensional (3D) finite-difference time-domain (FDTD) approach analyses the optics and optimization of the complete solar cell. The investigations allow the optimized planar PSC to determine the
J
SC
of > 21 mA/cm
2
. The optical performance of the planar device is limited due to higher optical losses; hence, the current study proposes a PSC design embedded with Ag nanoparticles. The proposed PSC can improve the
J
SC
by ~ 17% (up to 24.5 mA/cm
2
) than the planar device owing to improved light trapping, further boosting the PSC's energy conversion efficiency (ECE). A detailed discussion on film realization and solar cell optics is provided.
•The influence of Ar:O2 gas flow on O2 concentration in WOX film is investigated.•O2 concentration also affects the WOX film’s thickness.•The impact of O2 concentration on the film’s optical ...properties is discussed.•WOX film is suitable as an electron transport layer for photovoltaic applications.•3D electromagnetic simulations investigate optics of perovskite solar cells.
Tungsten oxide (WOx) has been widely investigated due to mainly its optoelectronic properties. This study primarily aimed to examine the influence of oxygen concentration on the structural and optical properties of WOx films. Herein, WOx thin films have been prepared by reactive sputtering method at low power (50 W) while controlling the Ar:O2 gas flow rate to vary oxygen concentration. Energy Dispersive X-ray (EDX) analysis reveals that the oxygen concentration depends on the gas flow rate. Such oxygen concentration changes affect the film’s thickness, confirmed by the field emission scanning electron microscope (FESEM). Atomic force microscopy (AFM) analysis ensures the dependency of surface roughness of the films on the oxygen concentration. The developed films exhibit the amorphous state as validated by X-ray Diffraction (XRD) analysis. The Ultraviolet–Visible (UV–Vis) spectroscopy measurement was also conducted to determine transmittance and absorbance of the film, which further allows realizing necessary optical parameters, such as absorption coefficient, skin depth, energy bandgap, refractive index, extinction coefficient, etc. The oxygen concentration-dependent optical parameters are investigated in the spectral range of UV to near-infrared regions to ensure the use of WOx for optoelectronic device applications. Finally, we considered the optimized WOx film as a potential electron transport layer (ETL) to realize an efficient perovskite solar cell. The optics and optimization of this solar cell were studied by finite-difference time-domain (FDTD) simulations. The investigation allows us to calculate the maximum quantum efficiency (QE) and short-circuit current density (JSC) of ~90% and 22.1 mA/cm2, respectively.
A potential solar absorber material, sputtered kesterite Cu2ZnSnS4 (CZTS) thin film, has been extensively studied in recent years due to its advantageous properties, including the earth abundance of ...its constituent elements, nontoxicity, suitable band gap, and high absorption coefficient. 2000 nm CZTS thin films were deposited on soda lime glass by a sputtering technique. The prepared films underwent a postannealing treatment for crystallization in which different temperatures and pressures were applied to understand its impact on film growth, phase formation, and stoichiometry. The annealed samples were subsequently characterized by Raman and UV-visible (UV-Vis) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The thickness of each film was measured using a surface profilometer and from a cross-sectional image obtained by SEM. The XRD pattern for each film showed characteristic (112), (220), and (312) peaks, and the phase purity was confirmed via Raman studies. Film surface morphology and roughness were studied by AFM. The root mean square roughness was found to increase with annealing temperature and base pressure. The chemical compositions of the prepared samples were analyzed by EDX, and the films showed desired stoichiometry. UV-Vis absorption spectroscopy indicated that the direct band gap energies (Eg) of the films were 1.47 eV–1.51 eV, within the optimum range for use in solar cells. These attractive properties of the sputtered CZTS thin film should heighten interest in its use as a solar absorber layer in the next-generation photovoltaic cells, suggesting that it possesses substantial commercial promise.
Tungsten oxide (WOx) thin films were synthesized through the RF magnetron sputtering method by varying the sputtering power from 30 W to 80 W. Different investigations have been conducted to evaluate ...the variation in different morphological, optical, and dielectric properties with the sputtering power and prove the possibility of using WOx in optoelectronic applications. An Energy Dispersive X-ray (EDX), stylus profilometer, and atomic force microscope (AFM) have been used to investigate the dependency of morphological properties on sputtering power. Transmittance, absorbance, and reflectance of the films, investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, have allowed for further determination of some necessary parameters, such as absorption coefficient, penetration depth, optical band energy gap, refractive index, extinction coefficient, dielectric parameters, a few types of loss parameters, etc. Variations in these parameters with the incident light spectrum have been closely analyzed. Some important parameters such as transmittance (above 80%), optical band energy gap (~3.7 eV), and refractive index (~2) ensure that as-grown WOx films can be used in some optoelectronic applications, mainly in photovoltaic research. Furthermore, strong dependencies of all evaluated parameters on the sputtering power were found, which are to be of great use for developing the films with the required properties.
Crumb rubber (CR) from scrap tires is used as a partial replacement of fine aggregates in cement paste. This promotes the sustainable development of the environment, economy, and society, as waste ...tires are non-biodegradable and flammable. They occupy large landfill areas and are breeding grounds for mosquitoes and rodents. Inclusion of CR in mortar leads to several improvements on the mixture properties such as ductility, toughness, and impact resistance. However, it exhibits lower strengths and Modulus of Elasticity (ME). Therefore, to promote the use of mortar containing CR, it is vital to improve its mechanical strength. Past studies proved that nano-silica (NS) improves the strength of concrete due to the physico-chemical effects of NS. This study aims to examine the mechanical properties of crumb rubber mortar containing nano-silica (NS-CRM) and to develop models to predict these properties using Response Surface Methodology (RSM). Two variables were considered, CR as partial replacement to sand by volume (0%, 7.5%, 15%), and NS as partial replacement to cement by weight (0%, 2.5%, 5%). The results demonstrated a significant improvement in the mechanical properties of CRM when incorporating NS, and the models developed using RSM were acceptable with a 2% to 3% variation.
Deep beams are more susceptible to shear failure, and therefore reparation is a crucial for structural reinforcements. Shear failure is structural concrete failure in nature. It generally occurs ...without warning; however, it is acceptable for the beam to fail in bending but not in shear. The experimental study presented the structural behavior of the deep beams of reinforced concrete (RC) that reinforces the web openings with externally connected carbon fiber reinforced polymer (CFRP) composite in the shear zone. The structural behavior includes a failure mode, and cracking pattern, load deflection responses, stress concentration and the reinforcement factor were investigated. A total of nine reinforced concrete deep beams with openings strengthened with CFRP and one control beam without an opening have been cast and tested under static four-point bending load till failure. The experimental results showed that the increase the size of the opening causes an increase in the shear strength reduction by up to 30%. Therefore, the larger the openings, the lower the capability of load carriage, in addition to an increase in the number of CFRP layers that could enhance the load carrying capacity. Consequently, utilization of the CFRP layer wrapping technique strengthened the shear behavior of the reinforced concrete deep beams from about 10% to 40%. It was concluded that the most effective number of CFRP layers for the deep beam with opening sizes of 150 mm and 200 mm were two layers and three layers, respectively.
Waste tire and fly ash (FA) are two waste materials whose disposal and rapid rate of accumulation are among the pressing sources of concern and threat to the environment. Although much research ...exists on the use of these materials in cementitious composites, very little literature is available on the effectiveness of combining them in high volumes for concrete production. This work aimed to utilize crumb rubber (CR) from waste tires as a partial replacement of fine aggregate at 15%, 22.25%, and 30% by volume, and high-volume fly ash (HVFA) replacement of cement at 50%, 60%, and 70% (by weight of cementitious materials) to produce high-volume fly ash–crumb rubber concrete (HVFA–CRC). Using the central composite design (CCD) option of the response surface methodology (RSM), 13 mixes were produced with different combinations and levels of the CR and FA (the input factors) on which the responses of interest (compressive, flexural, and tensile strengths) were experimentally investigated. Furthermore, the composite influence of CR and HVFA on the workability of the concrete was assessed using the slump test. The results showed a decline in the mechanical properties with increasing replacement levels of the CR and HVFA. However, up to 22.25% and 60% of CR and HVFA replacements, respectively, produced a structural HVFA–CRC with a compressive strength of more than 20 MPa at 28 days. Response predictive models were developed and validated using ANOVA at a 95% confidence level. The models had high R2 values ranging from 95.26 to 97.74%. Multi-objective optimization was performed and validated with less than 5% error between the predicted and experimental responses.
Graphene oxide-modified rubberized engineered cementitious composite (GO-RECC) is attracting the attention of researchers because of the reported benefits of the GO and crumb rubber (CR) on the ...strength and deformation properties of the composite. While it is well established that GO negatively affects the workability of cementitious composites, its influence on the attainment of the desired self-compacting (SC) properties of ECC has not yet been thoroughly investigated, especially when combined with crumb rubber (CR). In addition, to simplify the number of trial mixes involved in designing SC-GO-RECC, there is a need to develop and optimize the process using Design of Experiment (DOE) methods. Hence, this research aims to investigate and model using response surface methodology (RSM), the combined effects of the GO and CR on the SC properties of ECC through the determination of T
, slump flow, V-funnel, and L-box ratio of the SC-GORECC as the responses, following the European Federation of National Associations Representing for Concrete (EFNARC) 2005 specifications. The input factors considered were the GO by wt.% of cement (0.02, 0.04, 0.06, and 0.08) and CR as a replacement of fine aggregate by volume (5, 10, and 15%). The results showed that increasing the percentages of GO and CR affected the fresh properties of the SC-GORECC adversely. However, all mixes have T
of 2.4 to 5.2 s, slump flow of 645 to 800 mm, V-funnel time of 7.1 to 12.3 s, and L-box ratio (H2/H1) of 0.8 to 0.98, which are all within acceptable limits specified by EFNARC 2005. The developed response prediction models were well fitted with R
values ranging from 91 to 99%. Through the optimization process, optimal values of GO and CR were found to be 0.067% and 6.8%, respectively, at a desirability value of 1.0.
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•Detailed circuit design, DSSC fabrication method and their analysis have been provided.•The natural dye and conductive layer synthesis for DSSC is simple and low cost.•Structural, ...optical and electrical properties of the DSSC have been compared.•The optical electronegativity results indicate the π-bonding nature of the synthesized dyes.•Pereskia bleo dye shows the highest Jsc values as well as good device performance.
The rapid use of fossil fuels has led to quick industrialization, swift economic growth, improved living standards, a high release of greenhouse gas, and fast exhaustion of fuel resources, which is a big threat to the environment and climate changes. To keep the planet green, dye-sensitized solar cells (DSSCs) have attracted much attention as the third-generation solar cells. This article documented an extensive study on the efficient use of natural dyes (Portulaca grandiflora, pereskia bleo, and alternanthera ficoidea), mesoporous TiO2 photoanode, a carbon cathode, and conductive layers to improve efficiency of DSSCs at ambient conditions. All of the conductive/TiO2/natural dyes display enhanced structural, optical, and electrical properties. X-ray diffraction studies of conductive/TiO2 layers represent the tetragonal structure which is buttressed by the SEM imaging, whereas organic dyes are amorphous in nature. The integrated conductive/TiO2/natural dye films have good sensitization in the visible spectrum (380–750 nm) and possess a bandgap falling (1.25–1.50 eV) and high refractive index while the maximum optical conductivity is observed in pereskia bleo. On the other hand, alternanthera ficoidea and portulaca grandiflora exhibit higher electrical conductivity (7.5 × 1012 Scm−1) and optical electronegativity (1.777). The TiO2 photoanodes at a conductive layer thickness of 3886.8 nm with iodide/tri-iodide redox liquid electrolyte generated current densities of 0.071–0.106 mAcm−2 under AM 1.5 illumination. Furthermore, the short-circuit photocurrent density (JSC), open-circuit voltage (VOC), fill factor (FF), and the corresponding photon-to-current conversion efficiency (η) estimated from the J-V characteristic curves with an effective area of 1 cm2 calculated for pereskia bleoDSSC are JSC = 0.106 mAcm−2, VOC = 0.023 V,FF = 45, andη = 0.11%. This study will open up a new door to fabricate highly efficient solar cells by modifying different parameters (photoanode, conductive layer, hybrid active layer, or different electrolyte) that can achieve meaningful success in photovoltaic industries.
Nano-crystalline CdSe thin films of different thicknesses under sub-micron range were deposited on glass substrate via thermal evaporation route. A gradual deterioration in film crystallinity ...confirmed by XRD line profile analysis has been accompanied by a reduction in Cd to Se molar ratio as the film thickness decreases. A coordinated microstructural and crystallographic orientation distribution analysis explicitly demonstrated that CdSe tends to grow in nano-sized columns with hexagonal c-axis parallel to its growth direction on glass substrate. A thickness dependence of structural evolution was discussed in terms of aspect ratio of the columnar structure and dispersion in orientation of hexagonal (002) basal plane. The variation in the spectra of optical constants n(λ), k(λ) obtained from Swanepoel envelop method was interpreted in terms of crystallographic defects arising from stoichiometric disorder which was also accounted for the observed thickness dependent shifts in band gap and valence band split energy. The bathochromic shifts in dielectric and energy loss functions, optical conductivity, skin depth and cut-off energy were discussed in detail along with the variations in their spectral shapes in connection with the dispersion in the real and imaginary parts of complex refractive index, which might shed a new light upon holistic comprehension of thickness dependent optical properties of other chalcogenide semiconducting thin films.
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