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Role of Platinum Octaethylporphyrin(PtOEP) in PCPDTBT: PCBM solar cell performance
摘要： Bulk heterojunction polymer solar cells based on poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole) [6,6]:- Phenyl-C61 butyrie acid methyl ester (PCPDTBT: PCBM) blends were doped by different amount(0,0.5,1,2,3 and 6 mg) from Platinum Octaethylporphyrin(PtOEP). The effect of PtOEP on the surface morphology, Raman spectra, optical absorbance, and photovoltaic properties was studied. We found that the best performance for PCPDTBT: PCBM device with 33.5% enhancement in power conversion ef?ciency was achieved when we added 1 mg from PtOEP. The impedance spectroscopy was examined in the frequency range from 0.025 to 1000 KHz. The equivalent circuit model was analyzed in detail to evaluate the interface and recombination processes. The highest diffusion coef?cient and mobility were found for PCPDTBT: PCBM: PtOEP(1 mg)device, which records a more ef?cient exciton dissociation at the interface and a faster charge transport processes.
关键词： PCPDTBT,PtOEP,Impedance spectroscopy,Bulk heterojunction (BHJ),PCBM
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Clean Electrical Power (ICCEP) - Otranto, Italy (2019.7.2-2019.7.4)] 2019 International Conference on Clean Electrical Power (ICCEP) - Graphene-on-Silicon solar cells with graphite contacts
摘要： This paper proposes an innovative technology for top contacting graphene-on-silicon Schottky solar cells, making use of graphite glue instead of the commonly used Ti/Au bilayer. Current-Voltage light characterization allow immediately to appreciate the advantage of the innovative contact evidencing the highest FF ever obtained in a graphene/Si solar cell with pristine (undoped) graphene and without graphene/silicon interlayer. To better understand the electrical behavior of our devices, solar cells realized either with gold contacts or with graphite contacts are compared by means of the impedance spectroscopy analysis too. It is shown that gold contacts give rise to strongly distorted impedance spectra and that such a distortion is due to the contact resistance. Conversely, graphite contacts result in extremely regular impedance spectra, as expected for ohmic behaving contacts.
关键词： impedance spectroscopy,photovoltaics,graphene
更新于2025-09-12 10:27:22
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Binary ionic liquid electrolytes for copper indium sulfide quantum dot sensitized-TiO2 solar cell to achieve long-term durability
摘要： This work demonstrates a straightforward strategy to develop the copper-indium-sul?de (CIS) quantum dot-sensitized solar cells (QDSSCs) consisting of ionic liquids (ILs) as electrolyte instead of any volatile solvent. The power conversion ef?ciency (PCE) of the solar cell yielded with 0.36% in the presence of 1-butyl-3-methylimidazolium sul?de ([BMIm][S2?/Sn2?]) and 1-butyl-3-methylimidazolium thiocyanate ([BMIm][SCN]) exhibited an improvement of JSC and FF yielding with 0.75% (JSC: 8.69 mA cm?2, VOC: 0.32 V, FF 26.8%). It exhibited long-term stability within 20% drops after 72 h-continuous photo-irradiation and subsequent storage for more than 1300 h in dark. It is due to suppression of the volatilization of solvent and decomposition of sul?de/polysul?de (S2?/Sn2?) anions. The solar cell performances were found to promote as an increase of interfacial charge transfer ef?ciency between electrolyte and electrodes by means of electrochemical impedance spectroscopy.
关键词： Electrochemical impedance spectroscopy (EIS),Power-conversion ef?ciency (PCE),Ionic liquid electrolyte,Quantum dot-sensitized solar cell,Copper indium-sul?de (CIS) colloids
更新于2025-09-12 10:27:22
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Performance Enhancement of Dye-Sensitized Solar Cells by Utilizing Carbon Nanotubes as an Electrolyte Treating Agent
摘要： A new carbon nanotube (CNT) function is proposed herein for dye-sensitized solar cell (DSSC) applications. In this study, single-wall CNT is used as a treating agent to the conventional liquid electrolytes, which differs from the role of a gelator or an additive as reported in the literature. The experimental results show that the electrochemical properties of the electrolytes do not alter significantly after the CNT treatment; however, the conversion efficiencies of the DSSCs are evidently improved (from 8.15% to 8.70%), which is attributed mainly to the enhanced open-circuit voltages. Device characterizations indicate that the higher voltages are due to the suppression of charge recombination at the TiO2/electrolyte interface. Furthermore, based on the Raman and UV-Vis spectra of the electrolytes, the concentrations of triiodide and higher polyiodide species are reduced after the CNT treatment. The Raman and XPS spectral results further verify the adsorption of polyiodides on the CNTs. More importantly, because fewer polyiodides are present in the electrolyte, fewer electrons in the TiO2 can be recombined; therefore, higher voltages are achieved for the corresponding cells. Quasi-solid-state DSSCs fabricated using CNT-treated electrolytes also demonstrate better cell performance. This CNT effect is anticipated to facilitate the progress of DSSCs.
关键词： centrifugation,iodine,printable,impedance spectroscopy,redox couple
更新于2025-09-12 10:27:22
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Detecting and identifying reversible changes in perovskite solar cells by electrochemical impedance spectroscopy
摘要： The current status of electrochemical impedance spectroscopy (EIS) and related analysis on perovskite solar cells (PSC) is still unsatisfactory. The provided models are still vague and not really helpful for guiding the efforts to develop more efficient and stable devices. Due to the slow and complex dynamics of these devices, the obtained spectra need to be validated, which is hardly ever done. This study may be the first to provide fully validated impedance spectra and presents reproducible EIS time series at open circuit voltage (VOC) for more than 20 hours, with a total of 140 analysed spectra. We conclude that the observed changes stem from a temporary reduction of the electronically active area of the devices, as can be deduced from the inverse behaviour of resistance and capacitance. The changes in these values are almost 100% reversible if the devices are kept in the dark for only one day, while the time constant of the high-frequency process remains unchanged throughout the whole characterization procedure. The tested devices are full PSC devices that have proven to be stable over more than 500 hours, and the non-steady impedance measurements shine a critical light on previously published EIS data. With the results of this study, it can be rationalized that the high-frequency semicircle can serve as a good indicator for ionic migration by monitoring its consequences. The results presented here are helpful to quantify ionic migration on the device level in order to derive new stability criteria and countermeasures against degradation.
关键词： reversible changes,stability,electrochemical impedance spectroscopy,perovskite solar cells,ionic migration
更新于2025-09-12 10:27:22
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Improving the charge balance and performance of CdSe/ZnS quantum-dot light-emitting diodes with a sputtered zinc-tin-oxide electron-transport layer and a thermally evaporated tungsten-oxide charge-restricting layer
摘要： The charge carrier balance and performance of CdSe/ZnS quantum-dot light-emitting diodes (QD-LEDs) with a vacuum-deposited electron-transport layer (ETL) and carrier-restricting layer (CRL) were successfully improved. Optimizing the fabrication process of the reactively sputtered zinc-tin-oxide (ZTO) ETL and adopting a thermally evaporated tungsten-oxide (WOx) CRL improved the electron-hole balance, thus leading to QD-LEDs with improved performance. Impedance spectroscopy analysis was successfully exploited in investigating charge carrier injection into each layer of the QD-LED and electron-hole recombination behaviors. The QD-LED with optimized ZTO ETL and without WOx CRL exhibited 2600 cd m?2 luminance and 3.2 cd A?1 current efficiency, and the QD-LED with both optimized ZTO ETL and a WOx CRL exhibited 3900 cd m?2 luminance and 5.1 cd A?1 current efficiency. These results imply a practical method for improving the electron-hole balance and performance of QD-LEDs, and provide a reliable technique for analyzing the carrier behavior of QD-LEDs.
关键词： CdSe/ZnS quantum-dot,light-emitting diodes,tungsten-oxide,charge balance,zinc-tin-oxide,impedance spectroscopy
更新于2025-09-11 14:15:04
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Nanoparticulate Metal Oxide Top Electrode Interface Modification Improves the Thermal Stability of Inverted Perovskite Photovoltaics
摘要： Solution processed γ-Fe2O3 nanoparticles via the solvothermal colloidal synthesis in conjunction with ligand-exchange method are used for interface modification of the top electrode in inverted perovskite solar cells. In comparison to more conventional top electrodes such as PC(70)BM/Al and PC(70)BM/AZO/Al, we show that incorporation of a γ-Fe2O3 provides an alternative solution processed top electrode (PC(70)BM/γ-Fe2O3/Al) that not only results in comparable power conversion efficiencies but also improved thermal stability of inverted perovskite photovoltaics. The origin of improved stability of inverted perovskite solar cells incorporating PC(70)BM/ γ-Fe2O3/Al under accelerated heat lifetime conditions is attributed to the acidic surface nature of γ-Fe2O3 and reduced charge trapped density within PC(70)BM/ γ-Fe2O3/Al top electrode interfaces.
关键词： nanoparticulate metal oxides,accelerated lifetime,electrodes,thermal stability,degradation mechanisms,interfaces,inverted perovskites solar cells,impedance spectroscopy,charge traps density
更新于2025-09-11 14:15:04
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Structure–Activity/Stability Correlations from the Electrochemical Dynamic Responses of Titanium Anode Coatings Formed of Ordered TiO <sub/>2</sub> @RuO <sub/>2</sub> Microspheres
摘要： Spherical TiO2/RuO2 particles were synthesized by ultrasonic spray pyrolysis (USP) at 200 and 800?C. The activity for the oxygen and chlorine evolution reactions (OER and CER, respectively) and the dynamic responses from electrochemical impedance spectroscopy (EIS) of the USP powders, as well as of the corresponding coatings on Ti, were analyzed and are discussed. The loss of coating activity is discussed with respect to the differences in the EIS and cyclic voltammetry responses of the coatings in their active and inactive states. The 800?C-USP sample was found to be more active than the 200?C-USP sample for both the CER and the OER, whereas the stability of the former was considerably lower. The correlation between the structure, composition and morphology of the powder and the coating with the registered electrochemical properties is discussed. The EIS analysis of the coating resistance distributions induced by the thermal treatment of the powder indicated a complex combination of the pore resistance and the pseudocapacitive charge transfer resistance. An additional coating resistance, due to loose grain boundaries, was introduced into the coatings in their active and inactive state. The EIS analysis indicated the changes in TiO2-enriched core/RuO2-enriched shell structure, caused by the USP temperature.
关键词： TiO2/RuO2,cyclic voltammetry,electrochemical impedance spectroscopy,oxygen evolution reaction,chlorine evolution reaction,ultrasonic spray pyrolysis,coating stability
更新于2025-09-11 14:15:04
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Investigation of thermal and electrical properties of As–Se glasses modified with Cu using DSC and AC impedance spectroscopy
摘要： Investigations of thermal properties of CuxAs50Se50 ? x chalcogenides were carried out using a differential scanning calorimeter. It was established that copper introduction significantly affects the complexity of structural network. This was indicated by double-stage crystallization process in the compound Cu15As50Se35. Besides α relaxation, all the glasses during heating show β relaxation. The complexity of the network influences the conductivity values and transport properties in a way of higher DC and AC conductivity for the compound with the highest Cu share. Impedance spectra show two semicircles, indicating the existence of two polarization processes in different frequency ranges. The presence of kinetic and as well as diffusion processes in polarization of the samples with x = 10 and 15 at% of Cu strongly affects the unusually high values of the real part of dielectric permittivity in low- and medium-frequency range.
关键词： AC impedance spectroscopy,electrical properties,thermal properties,Cu modification,DSC,As–Se glasses
更新于2025-09-10 09:29:36
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BIFEVOX Composites: Manufacture and Characterization
摘要： Design of composites is a way to improve the quality of solid electrolytes. By mechanically mixing and annealing substituted bismuth vanadate with nanosized aluminum, bismuth, and zirconium binary oxides, we obtained heterogeneous materials Bi4V1.7Fe0.3O11 – δ/xAl2O3, Bi4V1.7Fe0.3O11 – δ/xBi2O3, and Bi4V1.7Fe0.3O11 – δ/xYSZ. The investigation tools were X-ray powder diffraction and electron microscopy with energy-dispersive microanalysis. The composition of materials was studied, the non-interaction of components was elucidated in the aluminum oxide and zirconium oxide composite series, and a nonuniform distribution of nanopowder particles across the surfaces and cleaves of sinters was discovered. The bismuth atoms from bismuth oxide were shown to be capable of incorporating into the Bi4Fe0.3V1.7O11 – δ structure. The charge transport characteristics of the materials were studied by impedance spectroscopy. No changes were observed in logσ–103/T trends in composites with various binary oxides and various oxide contents. An increase in binary oxide concentration was shown to give rise to an insignificant decay in electrical conductivity.
关键词： composite materials,bismuth vanadates,impedance spectroscopy,bismuth oxide,oxygen-ion conductors
更新于2025-09-10 09:29:36