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Substrate Diameter-Dependent Photovoltaic Performance of Flexible Fiber-Type Dye-Sensitized Solar Cells with TiO2 Nanoparticle/TiO2 Nanotube Array Photoanodes
摘要： Fiber-type dye-sensitized solar cells (FDSSCs) are attractive as an energy source of soft electronics due to low-costs, non-toxicity and especially, their indoor-weak-light workable features. The TiO2 nanotube array (TNA) can grow on flexible Ti wires directly using anodization technique, which is convenient and can provide better contact between substrate/TiO2. However, a systematic study of assembling efficient TNA on photoanode of FDSSC is limited. This study investigated the anodization voltage and time effects of growing TNA on Ti wires. TiO2 nanoparticles (TNP) are fabricated on TNA using dip-coating technique to compensate for low dye adsorption of TNA. Dip-coating rate is varied to optimize TNP thicknesses to provide effective dye adsorption and charge-transfer routes. The highest photon-to-electricity conversion efficiency (η) of 3.31% was obtained for FDSSCs with TNA/TNP photoanode prepared using 60 V as the anodization voltage and 40 cm/min as the dip-coating rate. The influence of titanium wire diameter on η of FDSSCs was studied. The bending test was carried out on flexible FDSSC assembled using plastic tube. The photocurrent retention of 84% is achieved for flexible FDSSC bended for 10 times. This work firstly provides facile ways to assemble efficient photoanode with composite TiO2 structures for FDSSC and opens new insights on studying titanium wire natures on FDSSC performance.
关键词： anodization,electrochemical impedance spectroscopy,fiber-type,TiO2,flexible,dye-sensitized solar cells
更新于2025-09-16 10:30:52
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Impedance Spectroscopy Study of Organic Photovoltaic Cells with an Inkjet Printed Hole-Extracting Graphene Oxide Layer
摘要： This paper deals with the study of light conversion efficiency of organic photovoltaic cells with an inkjet-printed graphene oxide layer. The graphene oxide is used in this experiment as a hole-extracting, electron blocking layer in bulk heterojunction organic solar cells based on DPP(TBFu)2:PC60BM blend. It is also studied the influence of the GO reduction (chemically, by UV radiation and by annealing) on the final efficiency of photovoltaic conversion. Power conversion efficiency and the transport of charge carriers are evaluated by measuring of current-voltage characteristics and mainly by impedance spectroscopy analysis. In this regard, using of graphene oxide and its reduced form showed negative influence on the device performance caused by an inefficient charge carrier collection at the short-circuit condition.
关键词： current‐voltage measurements,reduction,impedance spectroscopy,graphene oxide,organic solar cells
更新于2025-09-16 10:30:52
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Influence of bromide content on iodide migration in inverted MAPb(I <sub/>1?x</sub> Br <sub/>x</sub> ) <sub/>3</sub> perovskite solar cells
摘要： The effect of a systematic increase in the bromide content on mixed anion methyl ammonium lead halide, MAPb(I1?xBrx)3, perovskite solar cells is investigated. We show that at a critical bromide concentration (7.5%) we supress the slow impedance response from the cells. We link the changing impedance spectrum to a large increase in the activation energy for iodide motion. These results are corroborated by muon spin relaxation measurements, where we show that at the concentration of bromide typically used in high performance perovskite solar cells (17%) there is no sign of iodide motion in powders. Finally, we show JV curve hysteresis as a function of bromide content. The scan rate at which the maximum hysteresis index is observed does not change as the % Br is increased, leading us to conclude that the low frequency impedance response and the JV curve hysteresis are not caused by the same mobile ions.
关键词： bromide content,muon spin relaxation,perovskite solar cells,hysteresis,iodide migration,impedance spectroscopy
更新于2025-09-16 10:30:52
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Illustrating the Shell Thickness Dependence in Alloyed Core/Shell Quantum Dot based Light-Emitting Diodes by Impedance Spectroscopy
摘要： Colloidal quantum dots (QDs) are talented materials and have been extensively investigated in the field of photonics and optoelectronics due to their size-dependent optical properties. The core/shell structure of QDs with wide bandgap shell has been adopted for obtaining stable emission and high PL quantum efficiency. However, when employed in active devices such as light-emitting diodes (LEDs), the thick shell structure of QDs may impede the transportation of carriers thus deteriorate the device performance. In this work, the effect of shell thickness of CdSe/ZnS QDs on device performance is systematically studied through impedance spectroscopy (IS) by constructing the electron-only symmetric device architecture. It is found that the evolution of capacitance in the symmetric device under applied voltage reflects the charge accumulation within the device and predicts the LED performance. The lowest capacitance is evaluated in the symmetric device containing QDs with a medium shell size of 2.1 nm, showing improved performance in LED with the highest luminance and current efficiency (CE) of 26370 cd/m2 and 8.3 cd/A respectively.
关键词： impedance spectroscopy,light-emitting diodes,charge accumulation,shell thickness,Colloidal quantum dots
更新于2025-09-16 10:30:52
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Ion Transport in Laser-Induced Graphene Cation-Exchange Membrane Hybrids
摘要： Ion exchange membranes hybridized with laser-induced graphene (LIG) might lead to membranes with functional surface effects such as antifouling, antibacterial or joule heating, however, understanding the change in the electrical properties of the membrane is essential. Here we studied LIG-modified ion-exchange polymeric membranes using electrochemical impedance spectroscopy (EIS). The conductivity of the anionic sulfonated polyethersulfone membranes and the effective capacitance of the membrane-electrolyte interface were obtained by fitting the EIS spectra to an electrochemical equivalent circuit and compared to LIG-modified non-ionic polyethersulfone films. The transport selectivity (as relative permeability) of counter-ions (K+, Na+, Mg2+, Ca2+) across the membrane was quantified using the membrane’s conductivities obtained from the EIS measurements. The total ohmic resistance of the membrane was directly correlated to the polymer thickness, (with negligible contribution from the conductive LIG layer), thereby establishing EIS as a rapid, low-cost and non-invasive method to accurately probe substrate usage in LIG modification.
关键词： laser-induced graphene,electrochemical impedance spectroscopy,capacitance,ion exchange membranes,conductivity,ion transport
更新于2025-09-16 10:30:52
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Laser method of microscopic sensor synthesis for liquid and gas analysis using glucose and H2S as an example
摘要： Laser-induced deposition of metals from a solution has been used as a new method for the synthesis of microcomposite materials in the copper-silver system. It was shown that the obtained materials have good sensory properties with respect to the determination of D-glucose in aqueous solutions. It is also shown that it can be used for gas sensors. Control of sensory properties can be done by changing the method of deposition. X-ray diffraction, EDX, and impedance spectroscopy were used to characterize the materials obtained and it was shown that laser sequential deposition and coprecipitation of two metals give different results. An explanation of the results was proposed. It explains them by the eutectic nature of the interaction in the copper-silver system.
关键词： copper-silver system,impedance spectroscopy,D-glucose,EDX,sensory properties,X-ray diffraction,Laser-induced deposition,microcomposite materials,gas sensors
更新于2025-09-12 10:27:22
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Photoconversion efficiency of Titania solar cells co-sensitized with natural pigments from cochineal, papaya peel and microalga Scenedesmus obliquus
摘要： Three natural pigments obtained from cochineal, papaya peel, and the microalga Scenedesmus obliquus were tested as sensitizers in dye sensitized Titania solar cells. The absorption characteristics of the pigments and the photoelectrochemical parameters were studied to determine the photoconversion efficiency of the cells. The interfacial charge transport processes present in the individually sensitized and the co-sensitized cells were determined by electrochemical impedance spectroscopy (EIS). The highest efficiencies achieved for individual pigments after testing a set of different concentrations were 0.228, 0.093 and 0.064% using cochineal, papaya peel extract and Scenedesmus obliquus extract respectively. 0.36% conversion efficiency was reached in the sensitized cell using a combination of the three pigments. The efficiency reached is in the range of those reported for natural pigments. Papaya peel extract and chlorophylls from Scenedesmus obliquus were examined for the first time as possible sensitizers in DSSC.
关键词： photoelectrochemical parameters,energy conversion efficiency.,natural pigments,DSSC,mixed extracts,electrochemical impedance spectroscopy (EIS)
更新于2025-09-12 10:27:22
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Performance Enhancement of Betanin Solar Cells Co-Sensitized with Indigo and Lawsone: A Comparative Study
摘要： Co-sensitization is an important strategy toward e?ciency enhancement of solar cells by enabling better light harvesting across the solar spectrum. Betanin is a natural dye which absorbs light in the major portion of the incident solar spectrum (green region) and is the most e?cient natural pigment used in dye-sensitized solar cells. This study investigates the performance enhancement of a betanin solar cell by co-sensitizing it with two natural pigments which show complementary light absorption, indigo and lawsone, absorbing in the red and blue regions of the solar spectrum, respectively. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the pigment molecules, derived from density functional theory (DFT) simulations, con?rmed their optimal alignment with respect to the conduction band energy of the TiO2 semiconductor and reduction potential energy level of the I?/I3 ? electrolyte, a necessary requirement for optimal device performance. Lawsone solar cells displayed better performance, showing average e?ciencies of 0.311 ± 0.034%, compared to indigo solar cells showing e?ciencies of 0.060 ± 0.004%. Betanin was co-sensitized with indigo and lawsone, and the performances of the co-sensitized solar cells were compared. The betanin/lawsone co-sensitized solar cell showed a higher average e?ciency of 0.793 ± 0.021% compared to 0.655 ± 0.019% obtained for the betanin/indigo co-sensitized solar cell. An 11.7% enhancement in e?ciency (with respect to betanin) was observed for the betanin/indigo solar cell, whereas a higher enhancement of 25.5% was observed for the betanin/lawsone solar cell. Electrochemical impedance spectroscopy studies con?rmed that the higher e?ciency can be attributed to the higher electron lifetime of 313.8 ms in the betanin/lawsone co-sensitized solar cell compared to 291.4 ms in the betanin/indigo solar cell. This is due to the energy levels being more optimally aligned in lawsone compared to that of indigo, as observed in the DFT studies, and the lack of dipole moment in indigo, resulting in more e?cient charge separation and charge transfer in lawsone.
关键词： DFT simulations,indigo,electrochemical impedance spectroscopy,dye-sensitized solar cells,co-sensitization,betanin,lawsone
更新于2025-09-12 10:27:22
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Quantifying charge carrier density in organic solar cells by differential charging techniques
摘要： Accurate determination of charge carrier density in organic solar cells under light irradiation is essential because charge carrier density is directly related to the bimolecular recombination rate and open-circuit voltage of the cells. We investigate the robustness of transient photovoltage/current (TPV/C) and impedance spectroscopy (IS) to interference from the geometric capacitance of the cells (Cgeo) during quantification of the charge carrier density. TPV/C and IS accurately quantify the charge carrier density of bulk heterojunction cells with small Cgeo. For planar heterojunction cells with a larger Cgeo contribution, IS fails to separate the charge carriers in the organic layer from those in the electrodes. In contrast, TPV/C eliminates the effect of Cgeo and gives a reasonable estimation of the charge carrier density in the organic layer with the planar heterojunction, demonstrating that TPV/C is more robust than IS to interference from Cgeo of the cells.
关键词： transient photovoltage/current,geometric capacitance,charge carrier density,organic solar cells,impedance spectroscopy
更新于2025-09-12 10:27:22
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Study of some sensitizers for gel polymer electrolyte based sensitized solar cells (SSCs)
摘要： The performance of phthaloychitosan gel polymer electrolyte (GPE) based sensitized solar cells (SSCs) fabricated with different types of sensitizer have been studied in this work. Five types of sensitizer were used viz., curcumin, chlorophyll, (E)-4-hydroxyl-3-((4-iodophenyl)diazenyl)-2H-chromen-2-one (CAD5), (E)-4-hydroxyl-3-((4-methoxyphenyl) diazenyl)-2H-chromen-2-one (CAD7) and cadmium sulphide (CdS). These sensitizers were designated as S1, S2, S3, S4 and S5 respectively. The performance of the sensitized solar cells (SSCs) has been characterized and the experimental results showed that S1 (SSC fabricated with curcumin dye sensitizer) exhibits the best performance with short circuit current density (Jsc) of 3.18 mA cm-2, open circuit voltage (Voc) of 0.41 V, fill factor (FF) 0.57 and power conversion efficiency (PCE) of 0.73%.
关键词： Gel polymer electrolyte,Electrochemical impedance spectroscopy,Sensitizers,Sensitized solar cells
更新于2025-09-12 10:27:22