Development of assessment methods for photovoltaic module enhancing techniques using the lifespan parameter

The photovoltaic module (PV) enhancer is a technology used for improving the PV performance. Recently, much research has been conducted to propose new concepts of PV enhancer such as coolers and reflectors. The PV enhancer performance is assessed by the common existing methods available in the literature, which solely depends on total exergy or energy, volume, area, weight and the manufacturing cost. These assessment methods are useful but cannot assess the PV enhancer's performance when considering the lifespan parameter. Hence, this study is intended to solve the current problem by linking the lifespan parameter into the existing methods by proposing three enhanced assessment methods: yield times lifespan per cost per area, yield times lifespan per cost per volume and yield times lifespan per cost per weight. The PV enhancer with the highest values of these factors will have the optimum performance. The influential parameters and limitations of the enhanced assessment methods are investigated. It is shown that the proposed methods can assess and classify the performance of the PV enhancer with different models when the lifespan is considered in the analysis. These assessment approaches can be applied by manufacturers and designers of PV enhancers.

Towards a promising systematic approach to the synthesis of CZTS solar cells

This study aims to enhance the CZTS device's overall efficiency, the key research area has been identified in this study is to explore the effects of a novel, low-cost, and simplified, deposition method to improve the optoelectronic properties of the buffer layer in the fabrication of CZTS thin film solar cells. Herein, an effective way of addressing this challenge is through adjusting the absorbers' structure by the concept of doping, sensitized CdS thin film by the bi-functional linker, and an environmentally friendly catalytic green agent. The Linker Assisted and Chemical Bath Deposition (LA-CBD) method was introduced as an innovative and effective hybrid sensitization approach. In the one-step synthesis process, Salvia dye, Ag, and 3-Mercaptopropionic acid (MPA) were used. Generally, the results for all samples displayed varying bandgap as achieved between (2.21-2.46) eV, hexagonal structure with considerably decreased strain level, broader grain size, and dramatically enhanced crystalline property. Hence, the rudimentary CdS/CZTS solar cell devices were fabricated for the application of these novel CdS films. Preliminary CZTS thin film solar cell fabrication results in the highest conversion efficiency of 0.266% obtained CdS + Salvia dye, indicating the potential use of the CdS films as a buffer layer for CZTS photovoltaic devices.

New systematic study approach of green synthesis CdS thin film via Salvia dye

In this study, we aimed to increase the knowledge regarding the response mechanisms which were associated with the formation of CdS thin films. CdS thin film remains the most appealing alternative for many researchers, as it has been a capable buffer material for effect in film based polycrystalline solar cells (CdTe, CIGSe, CZTS). The Linker Assisted and Chemical Bath Deposition (LA-CBD) technique, which combines the Linker Assisted (LA) technique and the chemical bath deposition (CBD) method for forming high quality CdS thin film, was presented as an efficient and novel hybrid sensitization technique. CdS films were bound to soda lime with the help of electrostatic forces, which led to the formation of the intermediate complexes [Cd (NH₃)₄]²⁺ that helped in the collision of these complexes with a soda lime slide. Salvia dye and as a linker molecule 3-Mercaptopropionic acid (MPA) was used in the one step fabrication technique. Optical results showed that the bandgap varied in the range of (2.50 to 2.17) eV. Morphological properties showed a homogeneous distribution of the particles that aspherical in shape in the CdS + MPA + Salvia dye films. This technique significantly affected on the electrical characterizations of CdS films after the annealing process. The CdS + Ag + MPA + Salvia dye films showed the maximum carrier concentration and minimum resistivity, as 5.64 × 10 ¹⁸ cm⁻³ and 0.83 Ω cm respectively.

Mechanism and principle of doping: realizing of silver incorporation in CdS thin film via doping concentration effect

A high-quality buffer layer serves as one of the most significant issues that influences the efficiency of solar cells. Doping in semiconductors is an important strategy that can be used to control the reaction growth. In this study, the influence of Ag doping on the morphological, optical and electrical properties of CdS thin films have been obtained. Herein, we propose the mechanism of CdS film formation with and without Ag ions, and we found that changes in the reaction of preparing CdS by the chemical bath deposition (CBD) method cause a shift in the geometric composition of the CdS film. XRD showed that the position of peaks in the doped films are displaced to wider angles, indicating a drop in the crystal lattice constant. The optical analysis confirmed direct transition with an optical energy gap between 2.10 and 2.43 eV. The morphological studies show conglomerates with inhomogeneously distributed spherical grains with an increase of the Ag ratio. The electrical data revealed that the annealed Ag-doped CdS with 5% Ag has the highest carrier concentration (3.28 × 10¹⁵ cm^-3) and the lowest resistivity (45.2 Ω cm). According to the results, the optimal Ag ratio was obtained at Ag 5%, which encourages the usage of CdS in this ratio as an efficient buffer layer on photovoltaic devices.

Correction: Mechanism and principle of doping: realizing of silver incorporation in CdS thin film via doping concentration effect

Correction for ‘Mechanism and principle of doping: realizing of silver incorporation in CdS thin film via doping concentration effect’ by A. S. Najm et al., RSC Adv., 2022, 12, 29613–29626, https://doi.org/10.1039/D2RA04790J.

Long-term power forecasting using FRNN and PCA models for calculating output parameters in solar photovoltaic generation

This paper evaluated a 1.4 kW grid-connected photovoltaic system (GCPV) using two neural network models based on experimental data for one year. The novelty of this study is to propose and compare full recurrent neural network (FRNN), and principal component analysis (PCA) models based on entire year experimental data, considering limited research conducted to predict GCPV behaviour using the two methods. The system data was collected for 12 months secondly and hourly data with 50400 samples daily. The GCPV evaluates using specific yield, energy cost, capacity factor, payback period, current, voltage, power, and efficiency. The predicted GCPV current and power using FRNN and PCA were evaluated and compared with measured values to validate results. However, the results indicated that FRNN is better in simulating the experimental results curve compared with PCA. The measured and predicted data are compared and evaluated. It is found that the GCPV is suitable and promising for the study area in terms of technical and economic evaluation with a 3.24-4.82 kWh/kWp-day yield, 21.7% capacity factor, 0.045 USD/kWh cost of energy, and 11.17 years payback period.

In vitro antioxidant activity of Ficus carica L. latex from 18 different cultivars

As synthetic antioxidants that are widely used in foods are known to cause detrimental health effects, studies on natural additives as potential antioxidants are becoming increasingly important. In this work, the total phenolic content (TPC) and antioxidant activity of Ficus carica Linn latex from 18 cultivars were investigated. The TPC of latex was calculated using the Folin–Ciocalteu assay. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power (FRAP) were used for antioxidant activity assessment. The bioactive compounds from F. carica latex were extracted via maceration and ultrasound-assisted extraction (UAE) with 75% ethanol as solvent. Under the same extraction conditions, the latex of cultivar ‘White Genoa’ showed the highest antioxidant activity of 65.91% ± 1.73% and 61.07% ± 1.65% in DPPH, 98.96% ± 1.06% and 83.04% ± 2.16% in ABTS, and 27.08 ± 0.34 and 24.94 ± 0.84 mg TE/g latex in FRAP assay via maceration and UAE, respectively. The TPC of ‘White Genoa’ was 315.26 ± 6.14 and 298.52 ± 9.20 µg GAE/mL via the two extraction methods, respectively. The overall results of this work showed that F. carica latex is a potential natural source of antioxidants. This finding is useful for further advancements in the fields of food supplements, food additives and drug synthesis in the future.

Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers

Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.

A Comprehensive Study on Mo/CdTe Metal-Semiconductor Interface Deposited by Radio Frequency Magnetron Sputtering

Metal-semiconductor (MS) junction between Mo and CdTe, which is one of the fundamental issues for CdTe based solar cell, has been investigated for films deposited on different substrates. XRD pattern of Mo/CdTe films on the polyimide (PI) substrate shows a strong preferential orientation of MoTe2 in (100) at 2θ = 29.44 degrees, which becomes less apparent as deposition time of CdTe increases. However, on soda lime glass (SLG) no such XRD reflection pattern is observed. Moreover, from EDX measurement, Mo-Te compound also identifies MoTe2 at Mo/CdTe interface on PI substrate, which is not present on SLG. Bulk carrier concentration of Mo/CdTe films on PI substrate for lower deposition time of CdTe is found 1.42 x 10(18) cm(-3), which is almost equal to MoTe2. Thereafter, it decreases as CdTe growth time increases. The type of unintentionally formed MoTe2 on PI substrate is found to be n-type in nature. Lattice constants of a = 6.5 Å for CdTe and a = 3.52 Å for MoTe2 are found from nanostructure study by TEM.

Effect of Sn Doping on the Properties of Nano-Structured ZnO Thin Films Deposited by Co-Sputtering Technique

In this study, tin doped zinc oxide (ZnO:Sn) nano-structured thin films were successfully deposited by co-sputtering of ZnO and Sn on top of glass substrate. The effect of Sn doping on the microstructure, phase, morphology, optical and electrical properties of the films were extensively investigated by means of XRD, EDX, SEM, AFM, Hall Effect measurement, and UV-Vis spectrometry. The results showed that the undoped ZnO film exhibited preferred orientation along the c-axis of the hexagonal wurtzite structure. With increase of Sn doping, the peak position of the (002) plane was shifted to the higher 20 values, and ultimately changed to amorphous structure. The absorption edge was shifted to blue region which confirmed the excitonic quantum confinement effect in the films. Consequently, improved surface morphology with optical bandgap, reduced average particle size, reduced resistivity, enhanced Hall mobility and carrier concentration were observed in the doped films after vacuum annealing. Among all of the as-deposited and annealed ZnO:Sn films investigated in this study, annealed film doped with 8 at.% of Sn concentration exhibited the best properties with a bandgap of 3.84 eV, RMS roughness of 2.51 nm, resistivity of 2.36 ohm-cm, and Hall mobility of 83 cm2 V(-1) s(-1).

Properties of a-SiGe Thin Films on Glass by Co-Sputtering for Photovoltaic Absorber Application

Non-hydrogenated amorphous Silicon-Germanium (a-SiGe) thin films were deposited at two different base pressures by RF magnetron co-sputtering. Moreover, an ex-situ thermal annealing was carried out to investigate the material properties to be suitable as the bottom cell of multi-junction solar cells. Compositional study of the films using EDX showed Ge-rich thin films with 75 atomic% of Ge. XRD reflection study implied that all samples were entirely amorphous in nature. However, a significant improvement of morphology possibly due to low base pressure was observed while thermal annealing caused peening and reduction of surface inhomogeneity in both as-sputtered films. UV-VIS-IR analysis confirmed the FESEM results. The highest transmittance was observed in the as-deposited sample grown at 4 x 10(-5) Torr, which however reduced after thermal annealing. Tauc's model was implied for band gap determination and band gap energy as low as 1.07 eV was found in the annealed sample grown at lower base pressure (4 x 10(-6) Torr). Electrical properties of films were investigated by Hall effect measurement system and results found the reduction of resistivity with the same trend of optical band gap energy.

Electrodeposited p-type Co3O4 with high photoelectrochemical performance in aqueous medium

Electrofabricated p-Co₃O₄ based electrodes have shown efficient photoelectrochemical performance at low bias potentials in aqueous medium (∼6.5 mA cm⁻²vs. SCE at −0.3 V).