Cadmium Selenide Nanoparticles Research Articles

Gamma Ray-Induced Changes in Polyvinyl Alcohol/Carboxymethyl Cellulose/Cadmium Selenide Nanocomposite Films: Optical Analysis for Optoelectronic Devices

In order to create nanocomposite films (NC) of polyvinyl alcohol, carboxymethyl cellulose and cadmium selenide nanoparticles (PVA/CMC/CdSe), thermolysis and ex-situ casting techniques were used. The microstructure and shape of the CdSe nanoparticles (NP) were characterized with the Rietveld method and transmission electron microscopy (TEM). Rietveld refinement of the x-ray data showed that the prepared CdSe NP had the cubic zinc blend structure with a lattice parameter 6.057 Å. The TEM showed the formation of the dotted shape of CdSe with a particle size around 2 nm, confirming the quantum dot size of the mother phase CdSe. Samples from the prepared PVA/CMC/CdSe films were irradiated with γ radiation doses of 20−150 kGy. The resultant effects of the γ ray irradiation on the optical and color properties of the prepared films were investigated using UV–vis spectroscopy and the International Commission on Illumination (CIE) color difference technique. When the γ dose was increased to 150 kGy, the maximum dose used, the direct and indirect optical band gaps (Eg) decreased. We attribute this decrease to the domination of crosslinking that destroyed the ordered structure and thus increased the amorphous regions. In addition, we used the optical dielectric loss (ε”) to identify the type of microelectronic transition for the PVA/CMC/CdSe NC samples, which was found to be a direct allowed transition. The effect of γ ray irradiation on the absorbance, extinction coefficient, refractive index, dielectric parameters and optical conductivity of the NC samples were studied. The enhancement in the optical properties indicated that the γ radiation is a useful tool that allows the use of the resulting PVA/CMC/CdSe NC in optoelectronic devices. Finally, the color differences between the pristine and irradiated films were estimated. The irradiated PVA/CMC/CdSe NC film exhibited significant color differences relative to the pristine films.

Bioelectrochemically triggered apoferritin-based bionanoreactors: synthesis of CdSe nanoparticles and monitoring with leaky waveguides.

Herein, we describe a novel method for producing cadmium-selenide nanoparticles (CdSe NPs) with controlled size using apoferritin as a bionanoreactor triggered by local pH change at the electrode/solution interface. Apoferritin is known for its reversible self-assembly at alkaline pH. The pH change is induced electrochemically by reducing O2 through the application of sufficiently negative voltages and bioelectrochemically through O2 reduction catalyzed by laccase, co-immobilized with apoferritin on the electrode surface. Specifically, a Ti electrode is modified with (3-aminopropyl)triethoxysilane, followed by glutaraldehyde cross-linking (1.5% v/v in H2O) of apoferritin (as the bionanoreactor) and laccase (as the local pH change triggering system). This proposed platform offers a universal approach for controlling the synthesis of semiconductor NPs within a bionanoreactor solely driven by (bio)electrochemical inputs. The CdSe NPs obtained through different synthetic approaches, namely electrochemical and bioelectrochemical, were characterized spectroscopically (UV-Vis, Raman, XRD) and morphologically (TEM). Finally, we conducted online monitoring of CdSe NPs formation within the apoferritin core by integrating the electrochemical system with LWs. The quantity of CdSe NPs produced through bioelectrochemical means was determined to be 2.08 ± 0.12 mg after 90 minutes of voltage application in the presence of O2. TEM measurements revealed that the bioelectrochemically synthesized CdSe NPs have a diameter of 4 ± 1 nm, accounting for 85% of the size distribution, a result corroborated by XRD data. Further research is needed to explore the synthesis of nanoparticles using different biological nanoreactors, as the process can be challenging due to the elevated buffer capacitance of biological media.

Superior Photocatalytic and Antibacterial Activity of Cadmium Selenide Nanoparticles Doped by Titanium or Lanthanum

This contemporary work delineates the photocatalytic and antibacterial activity of titanium (Ti) and lanthanum (La)‐doped cadmium selenide (CdSe) nanoparticles produced by a simple wet chemical method. Studies using diffraction and microscopy reveal that the synthesized samples devised cubic crystalline structure. The incorporation of the dopant into the host material is analyzed using X‐ray diffraction, scanning electron microscope–EDAX, and transmission electron microscopic studies. The photocatalytic activity Ti‐ and La‐doped CdSe nanoparticles results in improved degradation toward methylene blue (MB) dye under direct solar irradiation. This unique behavior is ascribed to the enhanced light absorption tendency with larger charge separation efficiency. Ongoing operational factors like initial dye concentration, catalyst dose, pH, and duration are evaluated regarding their effects on MB dye degradation. The photocatalytic activity for MB follows pseudo‐first‐order kinetics. The antibacterial activity of Ti– and La–metal‐doped CdSe is tested against Pseudomonas arueginosa and Staph aureus bacteria. The Ti–CdSe and La–CdSe nanoparticles show good antibacterial activity after 24 h of bacterial growth Pseudomonas arueginosa and Staph aureus, respectively. Based on the findings, Ti–CdSe and La–CdSe nanoparticles exhibit an enhanced photocatalytic and antibacterial activity when compared with CdSe nanoparticles.

Nickel selenide nano-cubes anchored on cadmium selenide nanoparticles: First-ever designed as electrode material for advanced hybrid energy storage applications

The rational design and impressive performance of the desired electrode material are one of the top priorities in the field of the supercapacitor era. Chalcogenides are functional materials that attracted tremendous research due to their great electrochemical activity, non-toxicity, high theoretical capacities, low cost, high environmental safety, and tunable electronic configurations. Combining two different materials (compositing strategy) is a popular route to develop novel, robust, and highly efficient electrodes for high capacity, energy, and power delivery with good durability. Herein, for the first time, a high-performance hybrid supercapacitor is developed based on NiSe2, and CdSe and their composites, e.g., NiSe2/CdSe (denoted as CN-1, CN-2, and CN-3) via hydrothermal via ex-situ wet-chemical method. By changing the stoichiometry of the host compounds (e.g., NiSe2, CdSe), various nanocomposites take birth, such as; CN-1, CN-2, and CN-3. Notably, their capacitive performance was measured and compared in an aqueous alkaline media in KOH with three milli molar concentration. Subsequently, the CN-2 electrode displayed a good electrochemical energy storage performance of 358C/g capacity and lower overall resistance, which promotes the fast diffusion of electrolyte kinetics; hence, optimized electrochemical properties prove its importance for the fabrication of full cell development. More strikingly, the CN-2//AC hybrid supercapacitor revealed a high capacitance of 90 F/g, 40.5 Wh/kg energy density, and a maximum power of 7161.2 W/kg coupled with a high stability of 87.6 % (20 A/g) when repeatedly tested for long-term 15,000 cycling. The proposed method portrays a cost-effective and appealing runner for high-energy hybrid supercapacitors in future energy storage applications.

Kappa-carrageenan for benign preparation of CdSeNPs enhancing the electrochemical measurement of AC symmetric supercapacitor device based on neutral aqueous electrolyte

This study presents the development of an electrochemical supercapacitor with a cadmium selenide nanoparticles (CdSeNPs) electrode utilizing a straightforward and economical method based on kappa-carrageenan (κ-CGN). The structural, morphological, and optical characteristics of CdSeNPs were assessed. Activated carbon (AC) and green-prepared CdSeNPs were easily mixed to achieve excellent electrochemical properties. The nanoelectrode (AC@CdSe) was tested in an aqueous electrolyte of sodium sulfate (Na2SO4) with a concentration of 1 Molar. Specific capacitance (Csp) for the AC electrode and the AC@CdSe electrode at 1 A g−1 was calculated to be 103 and 480 F g−1, respectively. Besides, the symmetric supercapacitor AC@CdSe/AC@CdSe device has a high specific energy of 52 Wh kg−1 and a maximum specific power of 2880 W kg−1, with a specific capacitance of 115.5 F g−1. With a coulombic efficiency of between 82 % and 100 %, the device continues to maintain excellent capacitance after 10.000 cycles.

Effect of CdSe loading on bulk heterojunction solar cell parameters

Hybrid solar cells based on conductive polymer poly(o-toludine) (POT) with Cadmium Selenide nanoparticles (CdSe NPs) bulk heterojunctions (BHJ) were prepared by the direct mixing method and then the optical properties of the prepared materials were analyzed. The photovoltaic response of a hybrid film is studied by I –V measurements under simulated one-sun AM 1.5 illumination (100 mW cm-2). Three different CdSe load was tested to study the effect of CdSe loading on optical properties and efficiency of solar cell. Best ratio was 1:1 were gave 0.28 % efficiency. Also no photovoltaic effect for device with 75% CdSe load.

Optimization, kinetics and thermodynamics studies for photocatalytic degradation of Methylene Blue using cadmium selenide nanoparticles

In this study, the photocatalytic degradation of Methylene Blue was investigated using CdSe nanoparticles. CdSe nanoparticles were synthesized via a simple method and were characterized by FTIR, XRD, FESEM, BET, DRS and EDS techniques. The photocatalytic performance of the CdSe nanoparticles was optimized using Response Surface Methodology (RSM) under visible light. The independent variables involved initial pH, MB concentration, photocatalyst dosage, and irradiation time were evaluated and the optimum photodegradation efficiency of MB dye removal was achieved ˜ 92.80% at pH = 8, 20 mgL−1 of MB concentration, 0.02 g 50 mL−1 of CdSe dosage, and 20 min of irradiation time. Also, the photodegradation of MB by CdSe is obeyed pseudo-first-order kinetic model (k = 0.038 min−1). The thermodynamic results revealed that the photocatalytic degradation of MB is spontaneous and endothermic. Also, the evaluation of various scavengers confirmed that the MB photodegradation was mainly done by photogenerated holes and hydroxyl radicals.

Properties and White Light Photoresponses of CdSe Colloidal Nanoparticles

II–VI nanocrystalline semiconductor materails provide a wide range of applications in electronics, optoelectronics and photonics. The present paper reports the preparation of colloidal Cadmium selenide (CdSe) nanoparticles and study their optical properties. (CdSe) was produced by a chemical route procedure, with the ligand tri sodium citrate (TSC) serving as a complexing agent. Cadmium acetate is used as a Cd source, and sodium selenide is used as a Se precursor. The morphological and optical properties of the produced nanoparticles were determined using a Transmission electron microscopy (TEM) and Ultraviolet – Visible spectroscopy (UV-VIS).Thin films of CdSe capped with are deposited on the glass and aluminum substrates . AL/ CdSe/Ag MSM photodetectors have been fabricated and the electrical properties were measured in dark and light. The output data display that the photo currents of all diodes are increased with light. The fact that the films had dark electrical conductivity and photoconductivity indicates that they were semiconducting materials.

Optical, morphological, electrical properties and white light photoresponse of CdSe nanoparticles

ABSTRACT II–VI nanocrystalline semiconductors offer a wide range of applications in electronics, optoelectronics, and photonics. The study of the morphological, electrical, and optical properties of Cadmium selenide (CdSe) nanoparticles prepared with tri ethanolamine (TEA) as a complex agent is reported in the paper. Cadmium acetate as a Cd source and (Na2SeO3) as a Se precursor. Transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), energy dispersive x-ray (EDX), and ultraviolet-visible spectroscopy (UV-VIS) were used to characterise the synthesised nanoparticles for their optical, compositional, morphological, and electrical properties. The film of CdSe was deposited on the glass substrate. The electrical characterisation of CdSe thin films at various temperatures dark electrical conductivity and photoconductivity reveal that the films were semiconducting in nature, indicating the suitability of these films for photo sensor applications.

Effect of Sodium Selenosulfate Concentration on Microstructural, Morphological, and Luminescence Characteristics of Cadmium Selenide Nanoparticles

CBD-deposited cadmium selenide nanoparticles in acidic medium production at pH value of bath solution was stayed constant at 6.5 using EDTA as complexing agents; sodium selenosulfite acts as a source of Se2- ion and cadmium acetate as source of Cd2+ ion. The nanoparticles of binary compound CdSe were also grown at different concentrations of sodium selenosulfite, and the influence of this parameter on the behaviours of the nanoparticles was studied. The as-synthesized cadmium selenide nanoparticles are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and PL absorption spectroscopy. Cadmium-selenide nanoparticles were produced using various concentrations as 10, 15, and 20 milliliters on a microscopic glass plate by chemical technique at a growth temperature of 90 degree Celsius. Microstructural constraints realized from the X-ray diffraction pattern decrease in grain size with an increase of concentration (8.25 nm–0.01 nm). It witnessed that the synthesized nanoparticle has a cubic crystal structure with favoured direction towards the (111) Miller indices’ plane. The oriented peak was investigated from the planes (311) and (111). From patterns of PL emissions, it was detected that in increasing concentration of sodium selenosulfate intensity, the nanoparticles with small crystal size could represent maximum luminescence intensity associated with the larger crystal size. This is due to the fact that the amount of ions on the nanoparticle surface rapidly increases as the crystal size of the nanoparticles reduces. Additionally, the transporter recombination ratio was increased as the size of the transporter reduces resulting in an increase in the overlap between the electron and hole wave functions. SEM inspection of produced nanoparticles reveals that the surface is free of cracks and that the grains are spherically formed. The surface is coated with granules of consistent size and shape. There are no fractures or holes visible inside the thin films under examination.

CdSe-TiO2 nanocomposites film deposited by electrophoretic co-deposition towards quantum dots sensitized solar cells

In this paper, cadmium selenide (CdSe) nanoparticles were used in quantum dots sensitized solar cells (QDSSCs) as photosensitizer. Electrophoretic co-deposition was employed to deposit cadmium selenide – titanium dioxide (CdSe-TiO2) nanoparticles for the preparation of the QDSSC photoanode. Co-deposition of CdSe-TiO2 were used to prevent the need of thermal treatment to the photoanode which could cause cracks on surface. The formation of CdSe-TiO2 nanocomposites could increase the electron injection speed due to interdigitated between CdSe and TiO2 nanoparticles. CdSe nanoparticles were prepared using hot injection methods at reaction temperature 300 °C for 1 min reaction time. Titanium dioxide (TiO2) nanoparticles solution was prepared using surface modification by propionic acid and n-hexylamine. Cu2S/Brass counter electrode was used with polysulphide electrolyte. Prior to electrophoretic deposition (EPD), the CdSe nanoparticles solution were purified for two times. The efficiency of the QDSSC assembled with photoanode deposited with 250 V and 90 s was the highest amongst of the other EPD parameter studied, were at 2.920 × 10−3 %.

Studies on the photocatalytic activity molybdenum doped cadmium selenide nanoparticles towards indigo carmine dye degradation under solar light

In the present study, molybdenum doped cadmium selenide (Mo-CdSe) nanoparticles photocatalyst has been synthesized and utilized for the degradation of indigo carmine dye under solar light irradiation. Mo-CdSe nanoparticles were characterized by X-ray diffraction (XRD), ultraviolet spectroscopy, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDAX), transmission electron microscopy, thermo gravimetric (TGA) and FTIR studies. The XRD and EDAX spectrum confirms the presence of Mo onto CdSe matrix. Thermal proved that the Mo-CdSe nanoparticles possessed greater thermal stability than CdSe nanoparticles. Photodegradation studies under solar light irradiation revealed that the Mo-doped CdSe nanoparticles exhibit higher photocatalytic activity than that of pure CdSe nanoparticles. This significant improvement in the photocatalytic efficiency of Mo-CdSe nanoparticles photocatalyst under solar light irradiation can be attributed to the presence of Mo on the CdSe nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by the Mo and better charge separation.

A brief Review on the physical properties of Cadmium selenide nanoparticles and zinc sulfide nanoparticles and applications

A brief Review on the physical properties of Cadmium selenide nanoparticles and zinc sulfide nanoparticles and applications

Study of the effect of capping agent variation on P3HT:CdSe hybrid solar cells

We present here a new study on the incorporation of cadmium selenide (CdSe) nanoparticles (NPs) in Poly-3-hexylthiophene (P3HT) polymer matrix. Our aim is to improve the performance of the hybrid solar devices by varying capping agents on top of CdSe NPs for each active layer sample. We investigated the optical properties of differently capped Bulk Heterojunction (BHJ) P3HT:CdSe cells. We extracted the optical constants (refractive index n, extinction coefficient k, real ε′ and imaginary ε′′ parts of dielectric permittivity) from fitted Transmittance T and Reflectance R spectra. Then, we were able to determine the static refractive index ns and permittivity εs, the plasma frequency ωp, the carrier density to effective mass ratio N = me, the optical conductivity roc, the optical band gap Eg and the oscillation and dispersion energies E0 and Ed, using equations proposed by the theoretical models such as Cauchy model, Drude-Lorentz, Tauc model, and Wemple-DiDomenico.

Combination of plant-mediated and sonochemical-assisted synthesis for preparation of low-toxic cadmium selenide semiconductor nanoparticles: Study of the effect of extraction techniques, characterization, comparative study of biological activities

The present study reported a green approach for sonochemical-assisted synthesis (SAS) of cadmium selenide nanoparticles (CdSe NPs) by using the aqueous extract of Leontice leontopetalum plant. The aqueous extract was obtained by ultrasonic- assisted extraction (UAE; 15 min, 50 °C) and microwave- assisted extraction (MAE; 15 min, 180, and 270 W) as two instrumental techniques. Next, the as-prepared aqueous extracts were used in a plant-mediated synthetic approach for the synthesis of CdSe NPs by applying the SAS technique. The synthesized samples were characterized via different techniques; including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible absorption; photoluminescence, and Fourier transform infrared spectroscopy. The average particle size of the prepared CdSe NPs was estimated below 50 nm. UV–Vis absorption and fluorescence techniques indicate a wide absorption band around 360–420 nm and an intense emission peak around 460 nm, respectively. After green synthesis and characterization, antimicrobial, antioxidant, and antifungal properties of the aqueous plant extracts as well as their corresponded CdSe NPs were evaluated by different assays, comparatively. Moreover, the genotoxicity and toxicity potential of the samples were investigated. The results indicate the significant antimicrobial activity of the extracts as well as the CdSe NPs, with the negligible toxicity and genotoxicity impacts.

Investigation on the photocatalytic activity of chemically synthesized zirconium doped cadmium selenide nanoparticles for indigo carmine dye degradation under solar light irradiation

A simple chemical methodology has been adopted for the synthesis of zirconium (Zr) doped and un-doped cadmium selenide (CdSe) nanoparticles for the application towards photocatalytic degradation of indigo carmine (IC) dye under solar light irradiation. The as prepared Zr-CdSe (doped) and CdSe (un-doped) nanoparticles were characterized by ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD), Scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDAX) and Transmission electron microscopy (TEM) studies. The inclusion of Zr ion into the CdSe nanoparticles matrix was confirmed by SEM-EDAX and XRD studies. TEM studies confirm the zirconium ions are uniformly doped over the CdSe surface. The photocatalytic degradation performance of Zr doped and un-doped CdSe nanoparticles were examined for the degradation of IC dye under solar light irradiation. The experimental results showed that the Zr doped CdSe possessed greater photocatalytic activity in comparison to un-doped CdSe. Photodegradation process parameters such as the initial concentration of the dye, as well as the amount of catalyst and time were investigated. The photocatalytic degradation rate was favored by a high concentration of solution in respect to Langmuir–Hinshelwood model.

Кинетическое Монте-Карло моделирование роста нанокристаллов СdSe

Статья посвящена моделированию кинетики коллоидной кристаллизации наночастиц (NPs) селенида кадмия (CdSe). С учетом вкладов констант скорости реакции отдельных стадий модифицировано кинетическое уравнение, включающее константы скорости реакции, термодинамические и расчетные параметры и физические свойства. Использована модифицированная кинетическая модель на основе уравнения кристаллизации, где учтены вклады адсорбции, десорбции и миграции зародившихся частиц в разное время. Модифицированная модель предполагает, что при кристаллизации NPs CdSe мономерные звенья зависят от частоты переходов присоединения и отрыва комплекса мономер–CdSe. В этом случае превращения предшественника в мономер, формирование эффективного мономера и зародышеобразование переходят в стадию роста нанокристаллов (NC CdSe) с засеянной массой. В процессе полученный нанокластер будет и дальше расти за счет раннего созревания, старения и последующего роста в более крупный NC CdSe. Кинетическим методом Монте-Карло (КМС) аппроксимирована модель процесса зарождение–рост NC с учетом разных вкладов в константы скорости реакции. Модифицированная модель с использованием КМС позволяет описать зависимости кинетических констант скорости от среднего радиуса наночастиц как функцию времени, концентрации и распределения NC CdSe в заданное время. Описаны условия формирования NPs CdSe с эволюционной функцией распределения NC CdSe в пространстве размера. Результаты моделирования кинетики коллоидной кристаллизации CdSe могут быть использованы для управления скоростью зарождения и роста NPs CdSe, а также аналогичных систем при формировании качественных NC.

Cadmium Selenide Formation Influences the Production and Characteristics of Extracellular Polymeric Substances of Anaerobic Granular Sludge.

Feeding cadmium (II) and selenium (IV) simultaneously to anaerobic granular sludge with the aim of synthesizing cadmium selenide (CdSe) nanoparticles induces compositional changes in the extracellular polymeric substances (EPS) matrix of this sludge. A methanogenic anaerobic granular sludge was repeatedly exposed to Cd(II) (10-50mgL-1) and selenite (79mgL-1) for 300days at pH7.3 and 30°C in a fed-batch feeding regime for enrichment of Se-reducing bacteria and synthesis of CdSe nanoparticles. EPS fingerprints of the granular sludge, obtained by size exclusion chromatography coupled to a fluorescence detector, showed a significant increase in the intensity of protein-like substances with > 100kDa apparent molecular weight (aMW) upon repeated exposure to Cd(II) and Se(VI). This was accompanied by a prominent decrease in protein-like substances of aMW < 10kDa. The fingerprint of the humic-like substances showed emergence of a new peak with aMW of 13 to 300kDa in the EPS extracted from the Cd/Se fed granular sludge. Experiments on metal(loid)-EPS interactions showed that the CdSe nanoparticles interact mainly with loosely bound EPS (LB-EPS). This study showed that the formation of Se(0) and CdSe nanoparticles occurs in the LB-EPS fraction of the granular sludge and repeated exposure to Cd and Se induces compositional changes in the EPS matrix.

Active Bicomponent Nanoparticle Assembly with Temporal, Microstructural, and Functional Control.

Transient supramolecular self-assembly has evolved as a tool to create temporally programmable smart materials. Yet, so far single-component self-assembly has been mostly explored. In contrast, multicomponent self-assembly provides an opportunity to create unique nanostructures exhibiting complex functional outcomes, newer and different than individual components. Even two-component can result in multiple organizations, such as self-sorted domains or co-assembled heterostructures, can occur, thus making it highly complex to predict and reversibly modulate these microstructures. In this study, we attempted to create active bicomponent nanoparticle assemblies of orthogonally pH-responsive-group-functionalized gold and cadmium selenide nanoparticles with temporal microstructural control on their composition (self-sorted or co-assembly) in order to harvest their emergent transient photocatalytic activity by coupling to temporal changes in pH. Moving towards multicomponent systems can deliver next level control in terms of structural and functional outcomes of supramolecular systems.

Effects of cadmium ion concentration on the optical and photo-response properties of CdSe/PVP nanocomposites for white light sensing application

Cadmium selenide (CdSe) nanoparticles dispersed in the PVP matrix with varying concentrations of cadmium (Cd) ion complex have been synthesized through a low-cost chemical bath deposition technique to investigate the effects of cadmium ion concentration on its optical and photo-response characteristics. To confirm the formation of pure, stable, well dispersed, and highly crystalline spherical CdSe nanocomposites different characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectroscopy have been used. The optical band gaps and sizes of the nanocomposites are determined from the UV–Vis data while the surface-related emission properties of the CdSe nanocomposites are obtained from the PL data. The quantum confinement on the CdSe nanocomposites increases with the decrease of Cd ion concentration. I–V characteristics measurements have been done on the samples to investigate the photo-response properties of the samples. Various optical properties such as bandgap, near bandgap emission, and impurity emission are correlated with the photo-response properties of the samples. The photoresponse properties are found to become more suitable for application in white light photosensor with the increase of quantum confinement. Mechanisms related to the enhancement of photocurrent with respect to quantum confinement are also discussed in this paper.