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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Study of Se and Cl segregation in poly-crystalline CdSeTe
摘要： CdTe based thin film solar cells have shown to be competitive in terms of efficiency and low cost, but the polycrystalline structure and low minority carrier lifetime constrain CdTe based devices from reaching the theoretical efficiency limit. In this work, the effect of Se and Cl segregation in polycrystalline CdSeTe photovoltaic devices was studied. We demonstrated using two-photon time-resolved photoluminescence (TRPL) that the Se alloyed CdSeTe absorber layer shows high minority carrier lifetime, and used density functional theory (DFT) calculations to explain the origin of such high lifetime.
关键词： photovoltaic cells,II-VI semiconductor materials,cadmium compounds,selenium
更新于2025-09-19 17:13:59
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Preparation and characterization of seleniuma??decorated graphene quantum dots with high afterglow for application in photodynamic therapy
摘要： Graphene quantum dots (GQDs) was synthesized using a simple, rapid and affordable method and decorated with selenium at different molar ratios for the first time to obtain an efficient sample for use in photodynamic therapy. Surface modification of GQDs was carried out using polyethylene glycol (PEG) for conjugation with protoporphyrin IX (PpIX). Synthesized GQDs (Se: 0.3%) at 180°C had an emission spectrum that fairly coincided with the absorption profile of PpIX. A relative decrease of about 62.48% in the emission intensity of anthracene was recorded under illumination with UVC light in the presence of GQDs (Se: 0.3%) and the reduction for clung GQDs (Se: 0.3%) and PpIX during 90 min was about 70.68%. Singlet oxygen (1O2) generation was examined using a chemical method that showed significant enhancement in decomposition rate constant in clung GQDs–PEG–PpIX compared with GQDs and PpIX alone. Afterglow over 600 s showed that GQDs (Se: 0.3%) could be effective for near skin and even deep tumours.
关键词： photodynamic therapy,selenium,afterglow,protoporphyrin IX,graphene quantum dots
更新于2025-09-19 17:13:59
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High-yielding Pd <sub/>2</sub> (dba) <sub/>3</sub> ·C <sub/>6</sub> H <sub/>6</sub> -based four-fold Sonogashira coupling with selenophene-conjugated magnesium tetraethynylporphyrin for organic solar cells
摘要： A catalytic system using Pd2(dba)3$(C6H6)/PPh3/CuI for Sonogashira coupling was demonstrated to synthesize a selenophene-conjugated magnesium tetraethynylporphyrin Mg-TEP-(Se-DPP)4 (2a). The terminal alkynes of magnesium tetraethynylporphyrin with bromoselenophene-tethered diketopyrrolopyrroles (DPPs) to produce the desired star-shaped 2a in 80% yield. This molecule shows higher solubility in organic solvents, more efficient visible and near-infrared region absorption, and a narrower band gap compared with reference thiophene-conjugated congeners. Two strategies, namely, selenium substitution and end-capping, were investigated to optimize bulk heterojunction structures in the active layers of organic solar cells. The optimized device based on 2a:PC61BM exhibited the highest PCE of 6.09% among the tested devices after solvent vapor annealing, owing to efficient exciton dissociation, balanced carrier mobility, and suppressed carrier recombination in the film's ordered morphology.
关键词： end-capping,selenium substitution,Sonogashira coupling,selenophene-conjugated magnesium tetraethynylporphyrin,organic solar cells
更新于2025-09-16 10:30:52
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Enzyme-Catalyzed in Situ Synthesis of Temporally and Spatially Distinct CdSe Quantum Dots in Biological Backgrounds
摘要： The cellular machinery of metal metabolism is capable of making a wide range of inorganic nanoparticles and quantum dots. Individual enzymes from these metabolic pathways are being identified with metal reducing activity, and some have been isolated for in situ particle formation and labeling. We previously identified a glutathione reductase like metalloid reductase (GRLMR) from Pseudomonas moravenis stanleyae with a high affinity for the bioavailable selenium thiolate selenodiglutatione and exhibiting NADPH-dependent reduction of selenodiglutathione to Se(0), initiating the growth of pure selenium metal nanoparticles. In this study, we demonstrate that the GRLMR enzyme can further reduce selenium to a Se(2?) oxidative state, which is capable of nucleating with Cd(2+) to rapidly form CdSe quantum dots. We show that GRLMR can outcompete background sources of cellular selenium reduction (such as glutathione) and can control the kinetics of quantum dot formation in complex media. The resulting particles are of smaller diameter, with a distinguishingly shifted emission spectrum and superior full width at half-maximum. This study indicates that there is great potential for using GRLMR to study and design enzymes capable of controlled biosynthesis of nanoparticles and quantum dots, paving the way for cellularly assembled nanoparticle biosensors and reporters.
关键词： enzyme-catalyzed,CdSe quantum dots,nanoparticle biosynthesis,GRLMR,biological backgrounds,selenium reduction
更新于2025-09-12 10:27:22
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Fabrication of Sb2Se3 thin film solar cells by co-sputtering of Sb2Se3 and Se targets
摘要： Antimony selenide (Sb2Se3) has attracted scientific interest due to its many advantages such as its appropriate band gap, non-toxicity, element abundance, and high absorption coefficient (> 105 cm?1). However, selenium (Se) is easily lost at high vapor pressures, thus leading to Se vacancies and increased recombination centers in films. In this work, Sb2Se3 films with good crystallinity were fabricated by co-sputtering of Sb2Se3 and Se targets with a substrate temperature of 350 °C and without a subsequent annealing process. The crystal structural properties, surface morphology, and optical and electrical properties of films with different Se contents were explored. Finally, we fabricated solar cells with a structure of FTO/CdS/Sb2Se3/Au and achieved an efficiency up to 3.47%.
关键词： Thin film,Selenium supplement,Co-sputtering,Sb2Se3
更新于2025-09-11 14:15:04
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Investigation of photo-induced electron transfer between amino-functionalized graphene quantum dots and selenium nanoparticle and it's application for sensitive fluorescent detection of copper ions
摘要： Copper ions play an essential role in some biological processes. Currently, there is a need for the development of convenient and reliable analytical methods for the Cu2+ measurement. In the present work, a sensitive fluorescence method was developed for the determination of copper ions. Amino-functionalized graphene quantum dots (af-GQDs) and selenium nanoparticles (Se NPs) were synthetized, respectively, and they were characterized via transmission electron microscope, infrared spectrum analysis and X-ray photoelectron spectrum measurement. Photo-induced electron transfer (PET) between the prepared two nanomaterials could effectively quench the fluorescence of af-GQDs. Cu(II) was reduced to Cu(I) in the presence ascorbic acid and Cu2Se was finally generated on Se NPs surface, which led to the declined PET efficiency and inhibited the fluorescence quenching of af-GQDs. The change in fluorescence intensity was linearly correlated to the logarithm of the Cu2+ concentration from 1 nM to 10 μM, with a detection limit of 0.4 nM under the optimal conditions. The detections of copper ions in water samples were realized via standard addition method and the recovery values varied from 98.7% to 103%. The proposed fluorescence method was also employed to analyze the uptake of Cu2+ into human cervical carcinoma HeLa cells and cisplatin-resistant HeLa cells (HeLa/DDP cells). The experimental results indicate that the decreased hCTR1 expression level in HeLa/DDP cells weakened the uptake of copper ions into these drug-resistant tumor cells.
关键词： photo-induced electron transfer,selenium nanoparticles,cellular uptake,copper ions,fluorescence quenching,amino-functionalized graphene quantum dots
更新于2025-09-11 14:15:04
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Optical properties of selenium sulfide thin film produced via chemical dropping method
摘要： This paper describes the production of selenium sulfide (SeS2) crystalline thin film on commercial glass substrates, via chemical bath deposition. Transmittance, absorption, dielectric constant and refractive index of the produced films were investigated by UV/VIS Spectrum. It was found that changes occurred on the characteristics of the films and they were determined as a function of selenium sulfide concentration, which varied between 2 × 10?3 and 5 × 10?3 M. The structure of the film was analyzed using FTIR spectrum. The calculated refractive index values fell between 1.5 and 1.6, whereas the transmission ratio of the films was around 80–90%. Moreover, a peak in the reflectance was observed at 320–330 nm for all investigated samples. The highest dielectric constant for the films was obtained at the deposition concentration of 0.005 M. This study is believed to be useful for thin film production.
关键词： Selenium sulfide,Thin film,Chemical dropping,Organic thin film,SeS2 thin films
更新于2025-09-10 09:29:36
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Scalable, Highly Uniform, and Robust Colloidal Mie Resonators for All-Dielectric Soft Meta-Optics
摘要： All-dielectric nanoparticles (NPs) with high (>3.0) or moderate (1.7–3.0) refractive indices have become fundamental to meta-optics, as they enable low-loss, low-heating, and quenching-free magnetodielectric Mie resonances, which are difficult to achieve by use of plasmonic counterparts. However, a scalable and versatile synthetic route for such magnetodielectric NPs retaining high uniformity, roundness, and robustness has remained elusive. Thus, soft self-assembly still represents an underutilized method in the optical engineer’s toolset, which in turn limits the accessible range of meta-optics. Herein, a gram-scale and versatile synthesis of dielectric colloidal Mie resonators is presented, in which selenous acid precursors are converted into highly uniform, crystalline colloids by a low demand reaction. These crystalline selenium (c-Se) colloids enable strong electric and magnetic resonances due to their moderate refractive index (2.8–3.2 at optical frequencies), while simultaneously satisfying the requirements of high uniformity, roundness, and robustness. Even with these exotic properties, c-Se colloids are successfully self-assembled into various all-dielectric meta-optics systems including (i) metafluids exhibiting directional scattering, (ii) metamolecules with nanogap-dielectric resonances, and (iii) metacrystals with magnetodielectric bandgaps. The design space of all-dielectric meta-optics will be greatly expanded by utilizing soft self-assembly of c-Se colloids.
关键词： soft nanophotonics,self-assembly,colloids,selenium,3D all-dielectric meta-optics
更新于2025-09-10 09:29:36
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Solution-synthesized chiral piezoelectric selenium nanowires for wearable self-powered human-integrated monitoring
摘要： Smart sensing devices with high stretchability and self-powered characteristics are essential in future generation wearable human-integrated applications. Here we report for the first time scalable synthesis and integration of selenium (Se) nanowires into wearable piezoelectric devices, and explore the feasibility of such devices for self-powered sensing applications, e.g., physiological monitoring. The ultrathin device can be conformably worn onto the human body, effectively converting the imperceptible time-variant mechanical vibration from the human body into distinguishable electrical signals, e.g., gesture, vocal movement, and radial artery pulse, through straining the piezoelectric Se nanowires. Our results suggest the potential of solution-synthesized Se nanowire a new class of piezoelectric nanomaterial for self-powered biomedical devices and opens doors to new technologies in energy, electronics, and sensor applications.
关键词： Self-powered sensor,Selenium nanowires,Wearable electronics,Human physiological monitoring,Piezoelectric device
更新于2025-09-09 09:28:46
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Cascaded systems analysis of a-Se/a-Si and a-InGaZnO TFT passive and active pixel sensors for tomosynthesis
摘要： Medical imaging systems like full field digital mammography (FFDM) and digital breast tomosynthesis (DBT) commonly use amorphous selenium (a-Se) based passive pixel sensor (PPS) direct conversion x-ray detectors. On one hand, direct conversion detectors inherently offer better resolution characteristics in terms of a higher modulation transfer function (MTF), in comparison to the indirect CsI:Tl PPS x-ray imager. On the other hand, especially at lower doses, this superior performance of the direct imager is seldom retained in its detective quantum efficiency (DQE) curves. It is well known that a-Se PPS x-ray imagers suffer from high additive electronic noise originating from the from the amorphous silicon (a-Si) thin film transistor (TFT) array that is being used in the current back-plane technology. This degrades the noise power spectrum (NPS) and subsequently the overall DQE. To address this deficiency, we propose to replace the PPS back-plane by active pixel sensor (APS) back-plane technology, which has the potential to reduce the back-plane electronic noise by amplifying the input signal, especially at low doses. The proposed APS is based on amorphous In-Ga-Zn-O (a-IGZO) TFT technology, which can offer high mobility (5-20 cm2/V-s), low leakage current (< 10-13 A) and low flicker noise (Hooge’s parameter αH ~ 1.5 × 10-3), leading to better imager noise performance. To test our hypothesis, we used linear cascaded systems analysis to model the imaging performance (MTF, NPS and DQE) of the PPS and APS a-Se direct imagers. This model was first validated using experimentally measured data obtained for a 85 μm pixel pitch a-Se/a-Si TFT PPS imager. Using this model, we analyzed the noise performance of the direct a-Se and indirect CsI:Tl x-ray a-IGZO APS imagers at different dose and electronic noise levels. Obtained results clearly showed that lowering back-plane electronic noise can significantly improve the performance of the a-Se/a-IGZO TFT APS imager. Our simulated results showed that a higher DQE at lower radiation doses (maximum DQE of 0.6 can be achieved at an exposure level of 1 μGy) can be achieved with the a-Se detector, thereby making this combination a promising candidate for low dose applications like DBT.
关键词： cascaded analysis,active pixel sensors,amorphous selenium,x-ray detectors,metal oxide
更新于2025-09-04 15:30:14