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Effect of CdSe thickness deposited by electrophoretic deposition for quantum-dot-sensitized solar cell
摘要： Cadmium selenide (CdSe) and titanium dioxide (TiO2) nanoparticles in chloroform were deposited on fluorine-doped tin oxide (FTO) conducting glass-substrate by the electrophoretic deposition (EPD) method at varying voltages and deposition times. Firstly, TiO2 nanoparticles were deposited on FTO conducting glass-substrate at 150 V for 30 s by EPD method. After that, CdSe was deposited on TiO2 layer at 100 V for 60 s, 90 s, and 120 s by EPD method. The CdSe/TiO2 films were characterized using UV-visible spectroscopy (UV-vis) and scanning electron microscope (SEM). A complete quantum-dots-sensitized solar cells (QDSSCs) were assembled using polysulfide electrolyte and Cu2S counter electrodes. Polysulfide electrolyte was prepared with mixture of sulphur, sodium hydroxide and methanol/deionized water. The power conversion efficiency of 2% was achieved using a CdSe/TiO2 (100 V, 120 s) electrode, under simulated AM 1.5, 100 mW cm-2 illumination.
关键词： Cadmium selenide nanoparticles,quantum dots sensitized solar cell,electrophoretic deposition,titanium dioxide nanoparticles
更新于2025-09-16 10:30:52
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Influence of ZnTe separation layer thickness on optical properties in CdTe/ZnTe double quantum dots on Si substrates
摘要： We investigate the influence of the ZnTe separation layer thickness on the photoluminescence (PL) dynamics of CdTe/ZnTe double quantum dots (DQDs) on Si substrates. The results clarify that the DQD's structure effectively improves the limit of the carrier collection and the thermal stability of the corresponding single-layer QDs. The unusual temperature-dependent PL is explained using the single model for thermal redistribution of carrier states. This model indicates that the main nonradiative process at high temperatures is caused by scattering via multiphonons with longitudinal optical phonon energy of about 19–21.3 meV. The confinement-induced mixing and electron-carrier coupling effects cause blue-shift and enhanced PL intensity. We propose that the separation layer controls carrier dynamics in optoelectronic devices by modulating the thermal escape and e-h pairs in the intermixing layers.
关键词： Quantum dots,Silicon substrate,Cadmium telluride,Thermal escape,Carrier confinement
更新于2025-09-16 10:30:52
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Solution-processible Cd-doped ZnO nanoparticles as an electron transport layer to achieve high performance polymer solar cells through improve conductivity and light transmittance
摘要： In this work, electron transport layers (ETLs) with high charge transfer ability were prepared by doping ZnO nanoparticles with different concentrations of cadmium(Cd). The inverted polymer solar cell based on PTB7-Th: PC71BM as active layer and various concentrations Cd-doped ZnO (CZO) as ETLs were fabricated. The PCE of the device with optimized Cd content in the ZnO film was about 14.7% larger than that of the pure ZnO-based cells. The cadmium-doped ZnO(CZO) is a good candidate to be used as a high-quality transparent electrode in solar cell applications.
关键词： high electrical conductivity,cadmium doping,electron transport layers,ZnO nanoparticles,inverted polymer solar cells
更新于2025-09-16 10:30:52
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Investigation on Surface Properties of Mn-Doped CdSe Quantum Dots Studied by X-ray Photoelectron Spectroscopy
摘要： In this work, we report on the effects of incorporating manganese (Mn) dopant into different sizes of cadmium selenide (CdSe) quantum dots (QDs), which improves the electronic and optical properties of the QDs for multiple applications such as light-emitting diodes, lasers, and biological labels. Furthermore, the greener inverse Micelle method was implemented using organic ligand, which is oleic acid. This binding of the surface enhanced the QDs’ surface trap passivation of Mn-doped CdSe, which then increased the quantity of the output. In addition, the inverse Micelle technique was used successfully to dope Mn into CdSe QDs without the risk of Mn dopants being self-purified as experienced by wurtzite CdSe QDs. Also, we report the X-ray photoelectron spectroscopy (XPS) results and analysis of zinc blended manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs), which were synthesized with physical sizes that varied from 3 to 14 nm using the inverse Micelle method. The XPS scans traced the existence of the Se 3d and Cd 3d band of CdSe crystals with a 54.1 and 404.5 eV binding energy. The traced 640.7 eV XPS peak is proof that Mn was integrated into the lattice of CdSe QDs. The binding energy of the QDs was related to the increase in the size of the QDs.
关键词： quantum dots,semiconductor,chemical synthesis,cadmium selenide,X-ray photoelectron spectroscopy,manganese doped
更新于2025-09-16 10:30:52
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Simultaneously efficient light absorption and charge transport of CdS/TiO2 nanotube array toward improved photoelectrochemical performance
摘要： CdS has been widely used to modify TiO2-based photoanodes for photoelectrochemical (PEC) water splitting. Due to the poor interface contact between chalcogenides and oxides, however, such CdS modified TiO2 materials usually exhibit inefficient separation and transport of charges, leading to an unsatisfactory efficiency during the PEC water splitting process. Addressing this issue, we herein report a CdS/TiO2 nanotube array (CdS/TNA) photoanode that was fabricated through a successive ion layer absorption and reaction (SILAR) method with an additional subsequent annealing. This post-annealing process is essential to enhance the interface contact between the CdS and the TNAs, resulting in an accelerated transfer of photogenerated electrons from the CdS to the TNAs. In addition, the post-annealing also improves the light absorption capability of the CdS/TNA photoanode. The simultaneous enhancement of charge transport and light absorption provided by the post-annealing is essential for improving the PEC performance of the CdS/TNA photoanode. The CdS/TNA photoanode obtained by this strategy exhibits a much enhanced PEC performance in water splitting, and its photocurrent density and solar-to-hydrogen conversion efficiency could reach 4.56 mA cm?2 at 1.23 V vs. reversible hydrogen electrode and 5.61%, respectively. This simple but effective route can provide a general strategy for obtaining high-performance oxide-based photoelectrodes.
关键词： Photoelectrochemical water splitting,Nanotube arrays,Titanium dioxide,Cadmium sulfide
更新于2025-09-12 10:27:22
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Wet chemical etching of cadmium telluride photovoltaics for enhanced open-circuit voltage, fill factor, and power conversion efficiency
摘要： Cadmium telluride (CdTe) is one of the leading photovoltaic technologies with a market share of around 5%. However, there still exist challenges to fabricate a rear contact for ef?cient transport of photogenerated holes. Here, etching effects of various iodine compounds including elemental iodine (I2), ammonium iodide (NH4I), mixture of elemental iodine and NH4I (I?/I3? etching), and formamidinium iodide were investigated. The treated CdTe surfaces were investigated using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The CdTe devices were completed with or without treatments and tested under simulated AM1.5G solar spectrum to ?nd photoconversion ef?ciency (PCE). Based on Raman spectra, XRD patterns, and surface morphology, it was shown that treatment with iodine compounds produced Te-rich surface on CdTe ?lms, and temperature-dependent current–voltage characteristics showed reduced back barrier heights, which are essential for the formation of ohmic contact and reduce contact resistance. Based on current–voltage characteristics, the treatment enhanced open-circuit voltage (VOC) up to 841 mV, ?ll factor (FF) up to 78.2%, and PCE up to 14.0% compared with standard untreated CdTe devices (VOC ; 814 mV, FF ; 74%, and PCE ; 12.7%) with copper/gold back contact.
关键词： open-circuit voltage,fill factor,Cadmium telluride,wet chemical etching,photovoltaics,power conversion efficiency
更新于2025-09-12 10:27:22
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Material Property Changes in Defects Caused by Reverse Bias Exposure of CIGS Solar Cells
摘要： Partial shading of Cu(In,Ga)Se2 modules can lead to the formation of reverse bias induced wormlike defects. These wormlike defects act as local shunts and permanently decrease module output. A good understanding of the formation and propagation mechanisms of these defects is needed in order to mitigate the negative effects, or to prevent these defects from forming. In this article, wormlike defects were formed on small nonencapsulated cells by exposing them to reverse bias conditions. Scanning electron microscopy-energy-dispersive X-ray spectroscopy measurements showed a rearrangement of elements: Indium, gallium, and copper were replaced by cadmium, whereas selenium was replaced by sulfur in the area around the defect. Moreover, additional electronic-defect levels were found in that area with spectrally resolved photoluminescence spectroscopy. Based on the material changes in the area close to the wormlike defects, a propagation mechanism is proposed. The model assumes a chemical reaction as the driving force for propagation instead of melting because of ohmic heating.
关键词： photoluminescence (PL),photovoltaic (PV) cells,electric breakdown,reliability,thin film devices,Cadmium
更新于2025-09-12 10:27:22
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Performance Analysis of 0.4–1.2-μm CdTe Solar Cells
摘要： Thin-?lm cadmium telluride (CdTe) solar cells with an absorber thickness range of 0.4–1.2 μm were fabricated by close-space sublimation on a transparent MgZnO window layer. Microscopy cross sections showed that a signi?cant fraction of the CdTe crystallites extended throughout the absorber layer, and capacitance measurements demonstrated that the absorbers were depleted into forward bias. Current and ?ll factor loss analyses were used to identify dominant loss mechanisms in the devices as a function of absorber thickness, and photoluminescence measurements were increasingly in?uenced by back-surface recombination as the absorber was made thinner. The thinner CdTe devices showed modest current and ?ll-factor reduction but overall good diode quality, and the highest ef?ciency of 15% was achieved with 1.2-μm CdTe.
关键词： Close-space sublimation (CSS),photoluminescence (PL),loss analysis,thin cadmium telluride (CdTe)
更新于2025-09-12 10:27:22
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Monitoring of the Mechanism of Mn Ions Incorporation into Quantum Dots by Optical and EPR Spectroscopy
摘要： Synthesis of nanoparticles doped with various ions can significantly expand their functionality. The conditions of synthesis exert significant influence on the distribution nature of doped ions and therefore the physicochemical properties of nanoparticles. In this paper, a correlation between the conditions of synthesis of manganese-containing cadmium sulfide or zinc sulfide nanoparticles and their optical and magnetic properties is analyzed. Electron paramagnetic resonance was used to study the distribution of manganese ions in nanoparticles and the intensity of interaction between them depending on the conditions of synthesis of nanoparticles, the concentration of manganese, and the type of initial semiconductor. The increase of manganese concentration is shown to result in the formation of smaller CdS-based nanoparticles. Luminescent properties of nanoparticles were studied. The 580 nm peak, which is typical for manganese ions, becomes more distinguished with the increase of their concentration and the time of synthesis.
关键词： manganese,electron paramagnetic resonance (EPR),nanoparticles,quantum dots,zinc sulfide,cadmium sulfide,luminescence
更新于2025-09-12 10:27:22
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Type-II heterostructures of <b>α</b> -V <sub/>2</sub> O <sub/>5</sub> nanowires interfaced with cadmium chalcogenide quantum dots: Programmable energetic offsets, ultrafast charge transfer, and photocatalytic hydrogen evolution
摘要： We synthesized a new class of heterostructures by depositing CdS, CdSe, or CdTe quantum dots (QDs) onto α-V2O5 nanowires (NWs) via either successive ionic layer adsorption and reaction (SILAR) or linker-assisted assembly (LAA). SILAR yielded the highest loadings of QDs per NW, whereas LAA enabled better control over the size and properties of QDs. Soft and hard x-ray photoelectron spectroscopy in conjunction with density functional theory calculations revealed that all α-V2O5/QD heterostructures exhibited Type-II band offset energetics, with a staggered gap where the conduction- and valence-band edges of α-V2O5 NWs lie at lower energies (relative to the vacuum level) than their QD counterparts. Transient absorption spectroscopy measurements revealed that the Type-II energetic offsets promoted the ultrafast (10?12–10?11 s) separation of photogenerated electrons and holes across the NW/QD interface to yield long-lived (10?6 s) charge-separated states. Charge-transfer dynamics and charge-recombination time scales varied subtly with the composition of heterostructures and the nature of the NW/QD interface, with both charge separation and recombination occurring more rapidly within SILAR-derived heterostructures. LAA-derived α-V2O5/CdSe heterostructures promoted the photocatalytic reduction of aqueous protons to H2 with a 20-fold or greater enhancement relative to isolated colloidal CdSe QDs or dispersed α-V2O5 NWs. The separation of photoexcited electrons and holes across the NW/QD interface could thus be exploited in redox photocatalysis. In light of their programmable compositions and properties and their Type-II energetics that drive ultrafast charge separation, the α-V2O5/QD heterostructures are a promising new class of photocatalyst architectures ripe for continued exploration.
关键词： α-V2O5 nanowires,cadmium chalcogenide quantum dots,photocatalytic hydrogen evolution,programmable energetic offsets,Type-II heterostructures,ultrafast charge transfer
更新于2025-09-12 10:27:22