Deposited CdS Thin Films Research Articles

Exceptional and innovational analysis of n-CdS/p-Si solar cells based on software packages and bias point models: insights into theoretical and experimental characteristics of fabricated solar cells

The characteristics of a single solar cell made by CdS thin film deposition on a silicon glass substrate were estimated using simulation models in this study. An aluminum electrode was attached to a silicon wafer to produce a heterojunction, and the indium fingers were fashioned into another electrode and connected directly to the CdS layer. Simulation steps were performed using PV*SOL 3.0 software package and bias points (ISC, VOC ) models. In addition to the use of advanced programs such as MATLAB software (Shell SQ150 PV module), Mathcad 2000 program, and Origin Lab 2019 program.Simulation programs for extracting photovoltaic parameters have been executed together with the laboratory procedures. The simulation programs and experimental procedures aimed in general to know the (current-voltage) and (power-voltage) characteristics of the studied single-diode photovoltaic.

Effect of deposition time on chemical bath deposited CdS thin films properties

Effect of deposition time on chemical bath deposited CdS thin films properties

Annealing Assisted Structural Modifications in CdS Thin Films

The present article deals with synthesis of CdS thin films using cost effective chemical bath deposition method and study effect of annealing over the structural properties using X-ray diffraction pattern (XRD). The XRD pattern revealed shift in peak position and variation in intensity upon annealing at different temperatures; this may be attributed to annealing assisted modifications in composition of the thin films. The as deposited CdS thin films represents peaks corresponding to (002), (101), (111) and (110) which in case of annealed samples at 200 and 400oC get modified and slightly shifted with rising some new peaks corresponding to (200) and (001) respectively. The crystallite size of the CdS thin films upon annealing is observed to be increased this may be co-related to the fact energy induced grain growth.

Annealing assisted enhancement in photo response of PV deposited CdS thin films

CdS films were deposited on glass substrates by thermal evaporation method at room temperature. The effect of air annealing on structural, optical, and electrical properties of the films were characterized by XRD, UV–Visible spectroscopy, Hall effect and I-V measurements. The structural parameters crystallite size and residual stress showed an inverse relation between them. After annealing, the absorption edge was red shifted. Different models that use band gap of the films as input parameter were adopted to calculated refractive indices of the films. Annealing has resulted in the enhancement of carrier mobility. Finally, the spectral and time response of the pristine and annealed CdS films have been studied in detail and response time was found to be in the microsecond range. Annealing has reduced the response time considerably and made the films suitable for photodetector in the visible range.

Deposition of morphology-tailored CdS thin films by chemical bath approach

Thin films of CdS has gained conisderable attention due to their applications in photovoltaic devices. devices. Herein, we reported the deposition of CdS thin films using chemical bath deposition (CBD) by varying the Cd source concentration, pH, temperature and surfactant concentration. These variables were found to affect the crystallinity and morphology of as-deposited CdS thin films. Interestingly, well defined rod like morphologies and better crystallinity was observed at 1.0 M Cd source concentration, 80 °C, pH 10 and 40 mg sodium dodecyl sulfate (SDS) surfactant concentration.

Preparation and characterization of CdS thin film using chemical bath deposition (CBD) technique for solar cell application

The structural properties of CBD deposited CdS thin films have been studied by varying the processing parameters and Cd/S ratio of the starting Precursors in order to better understand the growth conditions. A CdS thin film was prepared on glass substrate by CBD method from a bath containing Thiourea and Ammonium hydroxide. The structural analysis was performed by X-ray Diffraction (XRD). The deposited CdS thin film was a cubic phase with small nano crystalline grains. The film was deposited at 60°C for 2 hours. After sintering the film at 300°C for 1 hour the color of the film was changed like dark yellowish and the thickness of the film was obtained 100 nm. The FTIR was done at room temperature over 350 cm-1 to 4500 cm-1 and it showed the existence of different functional group in the sample and their probable source. These studies have allowed us to establish a standard set of conditions for the fabrication of homogeneous and continuous very thin CdS films in laboratory and this preparation technique is also suitable for preparing highly efficient thin film due to its advantages such as simple, large area films, low deposition temperature and low-cost method.

Effect of deposition time and annealing process in chemical bath deposited CdS thin film

Effect of deposition time and annealing process in chemical bath deposited CdS thin film

Impact of RbF post deposition treatment on CdS/CIGSe and Zn(O,S)/CIGSe interfaces – A comparative HAXPES study

In conventional Cu(In,Ga)Se2 (CIGSe) solar cells a chemical bath deposited CdS thin film is used as a buffer layer. However, it is desired to replace CdS due to the toxicity of cadmium and the rather narrow bandgap energy of CdS. Zn(O,S) is considered to be one of the most attractive candidates as an alternative, non-toxic buffer layer with a larger bandgap. This paper aims to compare the properties of the CdS/CIGSe and the Zn(O,S)/CIGSe interfaces depending on the absorber composition and the application of an RbF post deposition treatment (PDT). Synchrotron-based hard X-ray photoelectron spectroscopy revealed a strong correlation of Cd diffusion and concentration of VCu in CIGSe before the PDT. Additionally, the RbF-PDT enhanced the Cd diffusion into the CIGSe. On the other hand, it was found that Zn atoms are not as easily incorporated into the CIGSe as Cd atoms. As a result, we consider the formation of donor-like ZnCu+ defects at the interface to be less likely than the formation of CdCu+ defects. Moreover, we observed that the Zn(O,S)/CIGSe interface is less sensitive to changes of the CIGSe composition and to the RbF-PDT compared to the CdS/CIGSe interface.

Chemical Vapour Deposition of CdS Thin Films at Low Temperatures from Cadmium Ethyl Xanthate

Thin films of nanometer sized cadmium sulfide were directly prepared by aerosol-assisted chemical vapor deposition (AA-CVD) method, cadmium ethyl xanthate complex was used as precursor material at 225 oC, 250 oC and 275 oC. The thermal decomposition of complex was characterized by thermal analysis, (thermogravimetric analysis (TGA) and a differential scanning calorimetry (DSC)). The prepared CdS thin films have been characterized by XRD and SEM- EDX analysis. TGA curves ensured that the rapid decomposition of [Cd(S2COEt)2] gives a CdS in single step between 150 oC and 200 oC. XRD patterns confirmed that the CdS particles crystalized as a hexagonal crystallographic phase at low temperatures. The grain size of particles increased with increasing the preparation temperatures from 225 oC to 275 oC,. The spherical CdS nanoparticals were observed in SEM analysis.

A comprehensive study on the effects of alternative sulphur precursor on the material properties of chemical bath deposited CdS thin films

Chemical bath deposition (CBD) method was used to deposit CdS thin films on soda-lime glass substrates by using n-methylthiourea (NTU) as an alternative sulphur source and were compared to typical thiourea (TU) precursor. The sulphur source concentration was varied from 0.01 M to 0.1 M and the impact on the microstructural, surface morphology, optical and electrical properties of the grown films were studied. Increasing n-methylthiourea concentration in the precursor yielded thinner films that are less than 100 nm thickness, surface morphology with average surface roughness of 6.4 nm, larger granular structure, wider band gap at 2.3 eV–2.6 eV range. Raman spectroscopy revealed Raman peak at 303 cm-1. In contrast, an increase in thiourea concentration resulted in thinner amorphous films, less distinct granular structure, narrower energy band gap from 2.3 eV to 2.4 eV and a resonance Raman peak at 302 cm-1. CdS thin film deposited from n-methylthiourea precursor at higher precursor concentration of 0.1 M showed better electrical properties such as lower resistivity and higher carrier mobility compared to the thin film deposited from typical thiourea precursor.

The effects of Zn incorporation on electrical, photoluminescence and spectral sensitivity of SILAR deposited CdS thin films

The SILAR deposited CdS films were incorporated with various concentrations of zinc using zinc acetate and zinc chloride precursors. The presence of zinc was found to alter the crystal structure and energy bandgap of the films. The bandgap increased by nearly 44% with the increase of zinc concentration in the films. The photoluminescence spectra of the films revealed the presence of several localized defects levels within the forbidden bandgap. The peak spectral response wavelength was found to vary from 500 nm to 400 nm with the increase of zinc. The photocurrent was found to increase with the Cd:Zn ratio. The films with relatively high concentrations of zinc were found to be better suited for the photodetector applications due to their higher photocurrent to dark current ratio.

Improved optical and structural properties of cadmium sulfide nanostructures for optoelectronic applications

In this study, the effect of ZnO seed layer on the growth of uniform CdS nanostructures was investigated using chemical bath deposition technique. Besides, the influence of molar concentration of reagents on the surface morphology, structural and optoelectrical properties of the deposited CdS thin films were examined. The CdS nanostructures were grown on bare glass and ZnO/glass substrates with different reagent molar concentrations. The results indicated an improvement in the homogeneity and uniformity of the grown CdS nanostructures on ZnO seed layer which can be due to the low lattice mismatch between ZnO and CdS structures. The CdS/ZnO samples were optimized by changing the molar concentration of reagents. A three–dimensional intersecting vertical nanosheet morphology with hexagonal structure was obtained when modified chemical concentration of 0.5 M was applied. The XRD pattern of CdS nanosheets indicated the hexagonal phase of CdS which were strongly orientated along (002) plane. The elevated intensity of dominant peak related to this sample confirmed the improved crystal quality of this CdS nanostructure comparing to the other samples. The UV–Vis spectrum demonstrated a high absorption coefficient for CdS intersecting nanosheets which might be due to the high specific surface area and light trapping behavior of this sample. The photoluminescence study also showed an improvement in optical properties of optimized CdS nanostructures. In order to study the optoelectrical properties of CdS nanostructures, metal–semiconductor–metal photodetectors were fabricated with different CdS samples and their current–voltage characteristics were analyzed. The results indicated an enhancement in photosensitivity, responsivity, and speed of photodetectors based on optimized CdS nanostructures.

Influence of bath temperature on surface modification and optoelectronic properties of chemical bath deposited CdS thin film nanostructures

Cadmium sulfide thin film nanostructures with various surface morphologies were synthesized using chemical bath deposition method (CBD) by varying bath temperature. Samples deposited at room temperature shows surface morphology similar to ‘seaweed’ pattern that crystallized in cubic structure, whereas those deposited at higher temperatures exhibit ‘honeycomb’ like surface pattern with hexagonal crystal structure. HRTEM images of the honeycomb structure shows that, nanowalls consist of CdS nanoparticles embedded with cadmium hydroxide just like ‘plum in pudding’. An improvement in conductivity and photosensitivity observed with increase in bath temperature. Photoluminescence measurements show that there are five emission peaks falls in green, red and infrared bands. The intensity of photoluminescence emission in the green band region found to be increased on thin films that deposited at elevated temperatures. Unique honeycomb like structures observed at 65 °C, shows comparatively high performance in structural and optoelectronic properties give it a slight edge in optoelectronic application.

Surface modification of CBD-grown CdS thin films for hybrid solar cell applications

The influences of interfacial modification by various dyes (Eosin-Y, D205, N719 and N3) on structural, morphological, optical and electrical properties of CdS-based hybrid solar cells are investigated. Structural properties showed the cubic growth of chemical bath deposited CdS thin films. Morphological analysis indicated that CdS specimen had a smooth and crack-free surface whereas P3HT layer coated on CdS thin films displayed spherical grains with nonuniform distribution. According to Tauc’s estimation conclusions, CdS and P3HT layers exhibited band gaps of 2.98 eV and 1.98 eV, respectively. The surface modification of CdS thin films by diverse dyes led to an increase in the absorption spectra of the CdS samples. Photoluminescence data showed that surface treatment of CdS samples by diverse dyes caused a decrease in the luminescence intensity of the CdS-based hybrid solar cells, meaning that efficient exciton dissociation was obtained. All the devices showed an obvious photovoltaic effect as a result of current density-voltage (J–V) curves. Furthermore, the highest solar cell efficiency was achieved for ITO/CdS/N3/Ag device as 0.322%, which could be ascribed to the surface modification of CdS thin films, giving rise to a formation of better interface between CdS and P3HT layers.

Cationic and anionic modification of CdS thin films by surface chemical treatment

Structural and physical properties of thin solid films can be modified by surface treatment. In this work, chemical bath deposited CdS thin films were treated both by a mercury chloride solution and by a saturated H2S gas. The effect of these treatments on electrical properties is clearly observed. Hg2+ doped CdS films show the highest dark and photo-conductivities, whereas the sulfurized CdS films become photo-insensitive. In Hg2+ doped CdS samples, new crystalline Hg3S2Cl2 and Hg2(ClO4)24H2O phases are found, and particle size reduction is observed at the surface. Both optical and electrochemical Mott-Schottky (M–S) analysis suggest an intraband level in the electronic structure of Hg2+ modified CdS. Sulfurized CdS films, on the other hand, keep unchanged their crystalline and morphological structure, as well as optical properties. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and M–S analysis indicate an increase of sulfur concentration at the surface of sulfurized CdS thin films, leading to a more stoichiometric CdS compound, which used to have lower conductivity. It demonstrates that ion exchange process or cationic substitution is effective for structural and physical property modification, whereas a gaseous saturation method or anionic modification results in a notable surface energy alteration in thin solid CdS films.

Spectroscopic Ellipsometry and Optical Dispersion Analysis of Nanocrystalline CdS Thin Films

This study reports on spectroscopic ellipsometry (SE) and optical dispersion analysis of chemically deposited CdS thin films. The CdS thin films were prepared using chemical bath deposition and annealed in N2 atmosphere at temperatures of 100, 200, 300, and 500 °C for 60 min. The optical constants of nanocrystalline CdS thin films were investigated with SE. The ellipsometric parameters of the CdS thin films were measured with SE in the photon energy range from 1.24 to 6.48 eV. To investigate the dispersion parameters, the dispersion of the refractive index of the thin films was analyzed using the Wemple–DiDomenico single-oscillator model (W–D model) and the Sellmeier model. The optical dispersion parameters of the oscillator energy, the dispersion energy, the average oscillator strength, and the average oscillator wavelength of CdS thin films were investigated. In addition, dispersion parameters of CdS thin films were investigated as a function of the annealing temperature. The dispersion parameters of CdS thin films by the W–D model and Sellmeier model change with annealing temperature, which causes the transformation of the crystal structure.

Low-Pollution and Controllable Selective-Area Deposition of a CdS Buffering Layer on CIGS Solar Cells by a Photochemical Technique

A chemical-bath deposition method has recently been applied for the industrial deposition of CdS buffer layers in high-efficiency Cu(In, Ga)Se2 (CIGS) solar cells; however, its massive raw material waste and heavy pollution have also hindered its long-range industrialization. In this study, a type of low-pollution and controllable selective-area deposition of CdS thin films on cells was proposed and conducted by a photochemical deposition (PCD) technique using an aqueous solution containing S2O32–, SO32–, and Cd2+. The as-deposited films are low-crystallinity, uniform, and compact with thicknesses of 30–50 nm. Moreover, the depositions of CdS thin films were further investigated by tuning the deposition time, absorption of cadmium ions, sulfur concentration, and light intensity. Additionally, an ion-by-ion mechanism was proposed for the growth of CdS thin films by a PCD technique. Furthermore, the optimal CdS thin layer was applied in CIGS solar cells, which showed a high efficiency of 10.45%. This resear...

A study on the enhancement of opto-electronic properties of CdS thin films: seed-assisted fabrication

A novel method of fabricating chemical bath deposited CdS thin films (CBD-CdS) by using electrodeposited CdS (ED-CdS) as a seed layer is reported. The resulting thin, compact, uniform and adherent seed-assisted CdS films (ED/CBD-CdS) show enhanced effective surface area compared to both ED-CdS and CBD-CdS. The phase of these CdS films was determined to be hexagonal. The fabricated ED/CBD-CdS films show higher photoelectrochemical (PEC) cell efficiency than either ED-CdS and CBD-CdS thin films. Carrier concentration and flat band potential values for ED/CBD-CdS systems are also found to be superior compared to both ED-CdS and CBD-CdS systems.

Effects of CdCl2 annealing temperatures on the properties of pulsed laser deposited CdS thin films and CdS/CdTe solar cells

In this work, a post annealing process in CdCl2 was applied to improve the quality of pulsed laser deposited CdS films, and the effect of annealing temperature on the quality of CdS films was studied. The research indicated that the grain size of CdS thin films obviously increased after the annealing process, and crystallinity and optical transmission performance of CdS films were enhanced as well. Moreover, the CdTe solar cell with the annealed CdS window layer obtained better performance. The annealing temperature is a significant factor in the annealing process. 420 °C may be an optimistic annealing temperature, since not only the CdS layer annealed at this temperature had good crystallinity and optical transmission performance with a relatively smooth surface, but also the photovoltaic device with this window layer obtained the best performance among all the samples, including higher short-circuit current, open-circuit voltage and efficiency, corresponding to 26.97 mA/cm2, 760.80 mV and 12.37% respectively.

Room temperature liquefied petroleum gas sensing using Cu 2 SnS 3 /CdS heterojunction

Abstract In the present work, for the first time, we report the fabrication of Cu2SnS3 (CTS)/CdS heterojunction for room temperature (27 °C) liquefied petroleum gas (LPG) sensing. The heterojunction is formed between sputter deposited CTS thin films and chemically bath deposited CdS thin films. The structural, morphological and optical properties of the thin films are evaluated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV–visible spectroscopy techniques, respectively. The fabricated heterojunction quality is evaluated from the forward biased current-voltage (I-V) study and the influence of annealing treatment of p-CTS thin film on LPG sensing properties of the heterojunction has been investigated. The CTS/CdS heterojunction exhibits maximum LPG response of 56% at room temperature under exposure of 780 ppm LPG concentration with 31s and 56s response and recovery time, respectively. The device retained 95% gas sensing stability after time period of 60 days suggesting that the fabricated CTS/CdS heterojunction is reliable and promising for LPG sensing. The factors affecting LPG sensing performance and plausible gas sensing mechanism are discussed in this study.