Open Circuit Voltage Values Research Articles

Flexible Self-Powered Sensing System Based on Novel DNA Circuit Strategy and Graphdiyne for Thalassemia Gene by Rapid Naked-Eye Tracking and Open-Circuit Voltage.

Based on the controllable instantaneous self-assembly ability of long-chain branched DNA nanostructures and the synergistic effect between nucleic acid amplification without enzymes, a highly sensitive and highly specific self-powered biosensing platform is developed. Two-dimensional graphdiyne is prepared, modified on flexible carbon cloth, and then functionalized with gold nanoparticles. When DNA mi-tubes are applied on it, target thalassemia gene CD122 triggers a dual-catalytic hairpin assembly reaction. The generated nanoscale DNA is precisely captured by the DNA mi-tube, exposing binding sites and activating the hybridization chain reaction to form long-chain branched DNA. Double-stranded DNA, along with dendritic DNA carrying a large number of guanine bases, precisely captures the signal molecule methylene blue (MB), generating a significant electrochemical signal. The redox reaction of MB also causes a proportional change in the system's color, achieving a colorimetric detection functionality. An efficient dual-mode self-powered sensing platform, therefore, is established for detecting the thalassemia gene CD122. The linear response range of target concentration to open-circuit voltage and RGB Blue value is 0.0001-10,000 pM. The detection limit under electrochemical mode is 36.3 aM (S/N = 3), and under colorimetric mode, it is as low as 12.1 aM (S/N = 3). The new method exhibits high sensitivity, excellent selectivity, and high accuracy, providing a universal strategy for designing novel biosensing platforms that can be extended to the detection of other biomolecules.

Experımental investıgatıon and mathematıcal modelıng of a novel solar thermoelectrıc generator incorporated with thermal condensing system

This study presents an investigation of the electrical energy output capability of a new thermoelectric generator system and reports on its design and fabrication. It was aimed to increase the current and voltage values by connecting six thermoelectric generators (TEGs) in series and parallel using a system with efficient thermal conversion. In this way, usable electrical energy was produced. The constructed system consists of heat pipes with solar glass tubes for collecting solar irradiance, a heat exchanger with an active cooling system for cooling, thermoelectric (TE) modules that were sandwiched between the upper heat chamber and heat sink, and a lower heat chamber adapted to heat pipes. The efficiency of electrical energy production in the system depends on the proper circulation of the working fluid in the system and active cooling. Numerical parameters such as open circuit voltage, solar irradiance and temperature values were collected from various parts of the constructed system, while electrical parameters such as short circuit current, maximum power output and Seebeck coefficient were obtained through calculation. Experimental measurements were taken at 41° 14′ N, 36° 26′ E with sea level on August 1, 6, and 8, 2019 and July 2, 3, and 4 of 2020. The data was collected from 8 a.m. to 3 p.m. The data of July 2 and 3, 2020, with the greatest numerical values, were used in the experimental presentation. The highest value of open circuit voltage was obtained 7.52 V on July 3, 2020, whereas the solar irradiance value was measured 662 W/m2. As a result, the value of maximum output power was calculated as 5.236 W. Following the experimental investigation, a numerical model with TEGs and a hybrid cooling system was developed. The developed model was validated against the data of open-circuit voltage, cold side and water outlet temperatures obtained from six different experimental tests. When the findings were analyzed, it was discovered that the developed model produced results that were compatible with the experimental measurements.

A coupled piezo-triboelectric nanogenerator based on the electrification of biaxially oriented polyethylene terephthalate food packaging films

This study reports that biaxially oriented silica-filled polyethylene terephthalate (BOPET) films used worldwide as food packaging materials combine unique dual electrification properties that enable the effective conversion of mechanical energy into electricity. The electricity output depends on the physical contact and separation of the polymeric matrix and triboelectric pair material with different affinities for electrons on its surface. To exploit the dual piezoelectric and triboelectric electrification of the films materials, a hybrid piezoelectric triboelectric nanogenerator energy harvester using this film as an electron source was assembled and tested. When BOPET film is paired with polyvinylidene fluoride (PVDF) nanofibre network, which due to the electronegativity difference gained electrons, the performance of the nanogenerator to the output open-circuit increases voltage values above 305 V, and the short-circuit current density and charge density to 12 ± 1μAcm−2 and 37 ± 2μCm−2, respectively. Further, underlaying the PVDF tribo-contact layer by a dielectric low permittivity spunbond non-woven polypropylene raises the performance of the nanogenerator more than doubled (624 V) with corresponding densities of 61 ± 7μAcm−2 and 101 ± 4μCm−2.

N-Isobutylphenothiazine as a reversible and stable catholyte in non-aqueous organic redox flow batteries

Nonaqueous organic redox flow batteries (NAORFBs) are the focus of current research because redox-active organic materials can be synthesized from abundant elements, and nonaqueous electrolytes offer higher open circuit voltage (OCV). The development of NAORFBs requires stable redox active materials in neutral forms and radical ions. N-substituted phenothiazines are organic catholytes with high electrochemical reversibility and stability. In this study, N-isobutylphenothiazine (iBuPT) was successfully synthesized in a single step from inexpensive precursors of 10H-phenothiazine and 1-bromo-2-methylpropane and used as catholyte material for NAORFB. iBuPT, a member of the N-substituted phenothiazine family, has a half-wave redox potential of 0.432 V, higher than most N-substituted phenothiazines. When iBuPT is coupled with anolyte 2,1,3-benzothiadiazole (BTD) with a half-wave potential of −1.82 V, the OCV value reaches 2.25 V. The half-wave potential of phenothiazine increases by 115 mV when an isobutyl group replaces the N‑hydrogen, and the stability of the radical cation formed during electrochemical oxidation improves. The steric hindrance can be used to tune redox potential and stability. The stability of the iBuPT radical cation is attributed to the steric shielding and resonance stabilization provided by the one isobutyl group and two phenyl rings attached to the redox-active center, N, from which electron transfer occurs. iBuPT is a promising catholyte candidate for NAORFBs.

Identification of novel indole-based dyes as active photo-sensitizers: Synthesis, photophysical, electrochemical and computational investigation

Novel D–π–A type indole-based compounds have been designed and synthesized as active photosensitizers for dye-sensitized solar cells (DSSCs). The molecular structures of indole-based compounds were identified and characterized using IR, NMR, and HRMS spectra data. The attributes of the indole-based compounds were evaluated in terms of their optical, electrochemical, light-harvesting efficiency (LHE), HOMO/LUMO level and redox behaviour. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were conducted to disclose the electronic and optical attributes of novel indole-based compounds. All the compounds revealed well-defined absorption with elevated absorptivity and a small band gap (2.89–3.01 eV). The HOMO to LUMO energy transfer percentage obtained from TD-DFT, for the synthesized compounds is in the range of 86%–99%. The projected light-harvesting efficiency (LHE) for the indole-based compounds is between 0.371 and 0.666. The greatest open circuit voltage (Voc) value was found in the methoxyphenyl-substituted indole-based compound, which is advantageous for DSSCs to obtain external maximum power output.

Structural and Photophysical Studies of Triphenylamine-Based Organic Dyes for Applications in DSSCs: Experimental and DFT Analysis

In order to study the connection between structure of the molecular and sensitizing performance in dye-sensitized solar cells, four new organic sensitizers with donor-pi spacer-acceptor structures were designed and synthesized. The structural characterization of all dye sensitizers was investigated using FT-IR, 13C and 1H NMR, CHN and UV–visible analyses. The electronic orbital transitions and optical properties were determined and discussed. (E)-2-cyano-3-(5-(3-(di-p-tolylamino)phenyl)furan-2-yl)acrylic acid (TPCA), (Z)-2-cyano-N′-((5-(3-(di-p-tolylamino)phenyl)furan-2-yl)acetohydrazide (TPCH), (E)-3-(5-(4-(bis(4-methoxyphenyl)amino)phenyl)furan-2-yl)-2-cyanoacrylic acid (MTPCA), and (Z)-N′-((5-(4-(bis(4-methoxyphenyl)amino)phenyl)furan-2-yl)methylene)-2-cyanoacetohydrazide exhibited band gaps (E gap) in the range from 1.51 to 1.78 eV with λ abs in the range of 486–589 nm. The dyes’ energy levels were investigated using the cyclic voltammetry technique and DFT calculations. To complement the comprehensive optical, electrochemical, and photovoltaic properties, density functional theory studies were conducted. Besides, important parameters such as open-circuit voltage, light harvesting efficiency, and band gap energy of the dye sensitizers were calculated and discussed. The theoretically calculated open-circuit voltage (V oc) values ranged from 1.28 to 2.04 eV, while the light-harvesting efficiency (LHE) values varied from 0.11 to 0.22. Indeed, this theoretical research could guide chemists to synthesize effective dyes for DSSCs.

Studies on photovoltaic properties of BFO/WO3 bilayer thin films for solar energy harvesting applications

BFO possess high remnant polarization (∼100 μC/cm2) and low direct band gap (∼2.7 eV) having potential for photovoltaic (PV) applications. In the present work, WO3 insulating layer is utilized with BFO and BFO/WO3 bilayer thin film structure is fabricated for reducing the leakage current along with possessing the low band gap and high ferroelectric polarization. In BFO/WO3 bilayer structure, the WO3 nanostructured thin film layer was fabricated utilizing rf-magnetron sputtering technique under the optimized parameters while BFO thin film layer was fabricated by altering the incident energy of excimer laser (150 mJ − 250 mJ) in Pulsed Laser deposition technique. BFO/WO3 bilayer structure prepared at 200 mJ laser energy demonstrated the superior ferroelectric properties (Ps = 63.24 µC/cm2 and Pr = 25.94 µC/cm2) with high values of short circuit photocurrent density (Jsc = ∼18 mA/cm2) and open-circuit voltage (Voc = ∼320 mV) under the UV illumination of Intensity = 160 mW/cm2 and λ = 355 nm. Obtained results suggest the utilization of prepared BFO/WO3 bilayer thin film structures on future novel energy harvesting purposes.

Hybrid cathodes of fluoride-ion batteries with carbon nanotubes

Solid-state fluoride-ion galvanic cells (metallic Ce anode, La1-xBaxF3-x (x ≈ 0.05) electrolyte) with carbon components in the cathode material – carbon nanotubes and nanocomposites based on them – have been created and studied. The investigations were carried out by means of cyclic voltammetry, impedance spectroscopy and electron microscopy. Tin fluoride SnF2 was used as a basic cathode material. The basic cathode was modified with additives of carbon nanotubes, which channels were filled with SnF2, PbSnF4 and their eutectic composition. Introduction of these additives lead to the charge-discharge currents improvement. The maximum value of open-circuit voltage (OCV ∼ 1.9 V) is observed with adding into the cathode material the nanocomposite of carbon nanotubes filled with the eutectic composition. Carbon nanotubes filled with tin fluoride SnF2@SWCNT proved to be the best additive in the cathode material. The sample has the biggest current density compared with the other samples (∼1.3 A/m2 at 180 °C, which is ∼4 times higher than that when using the basic cathode). The OCV of the galvanic cell with SnF2@SWCNT additive in the cathode material is stable within the investigated temperature range from 25 to 180 °C. For other galvanic cells temperature dependencies of OCV are decreasing. Results of the direct and alternating current investigations of the solid electrolyte in Ce/electrolyte/Ce symmetric cell show good converging. Direct current internal resistance of the solid electrolyte is defined by grain boundaries resistance. The impedance of a galvanic cell is determined by the composition and structure of SnF2 cathode material as the component of the cell with the highest resistance.

Electronic and Photochemical Passivation by a Classic Sunscreen Material Leading to Reduced Voc Losses and Enhanced Stability in Organic Solar Cells.

Organic solar cells (OSCs) have been a popular topic of research for a long time. As a well-known electron transport layer (ETL) material for inverted device architecture, sol-gel-derived zinc oxide (ZnO) displays certain defective surfaces that cause excessive charge recombination and lower device performance. While ultraviolet (UV)-light soaking is sometimes necessary for the ZnO layer to function properly, the latter can also cause the photodegradation of conjugated organic semiconductors. The photostability of OSCs has always been a hot research topic, as the radiation of UV light may cause changes in the material's properties, and that, in turn, may cause rapid attenuation of the devices. Herein, ZnO is modified by inserting the commonly used sunscreen ingredient benzophenone-3 (BP-3) between the photoactive layer, consisting of a PM6:Y6 blend, and ZnO to reduce the impact of UV radiation on the photosensitive layer. The addition of BP-3 successfully enhances the photovoltaic parameters, and a remarkable open-circuit voltage (Voc) value of 0.887 V is obtained for PM6:Y6-based inverted solar cells, corresponding to a Voc loss as small as 0.547 V. Finally, the application of this strategy increases the device's power conversion efficiency from 12.44 to 13.71% and provides improved UV stability.

Exploring promising photovoltaic properties of dithiophene-based non-fullerene chromophores for efficient organic solar cells: A DFT approach

Currently, non-fullerene-based acceptors in organic solar cells (OSCs) have gained significant attention of researchers owing to their particular characteristics. Herein, new W-shaped dithiophene based acceptor chromophores (D1-D8) possessing A-π-D-π-A configuration were fabricated via end group structural tailoring by utilizing promising acceptors groups. To probe the effect of end group manipulation on the optoelectronic properties of entitled chromophores, density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were accommodated at B3LYP/6–311 G(d,p) functional. Frontier molecular orbitals (FMOs) findings revealed that the derivatives (D1-D8) exhibited narrow band gap (1.191–2.110 eV) than that of reference chromophore (R=2.380 eV) due to efficient acceptor moieties. UV–Vis data collected in chloroform solvent revealed that λmax values of D1-D8 were existed in visible region (738.6–692.5 nm). Moreover, D2 and D4 proves to be the best chromophores exhibiting least band gap of 1.191 and 2.000 eV and broad absorption spectrum i.e., 738.573 and 735.986 nm, respectively. Among all the designed compounds, D2, D3, D4 and D6 manifested higher open circuit voltage values. Theoretical analysis disclosed that all the designed molecules exhibited almost comparable results with each other. Nevertheless, D2 and D4 provided significant findings and can be utilized as best candidate for use in optoelectronic devices.

Molecular modifications in fluorene core for efficient organic photovoltaic cells

The upgraded version of solar cells is organic photovoltaic (OPV) device. Substantial efforts have been made in development of new light sensitive materials (donor, acceptors and hole transport materials etc.), and further modification in different units of these materials and device fabrication process to achieve better performance in OSCs. Fluorene is a fluorescent, poor electron providing polycyclic aromatic molecule shows absorption from 220 to 310 nm with λmax of 329 nm and deep lying HOMO energy level which is favorable to gain high value of open circuit voltage (Voc) of fluorene based materials. Several acceptor materials have been synthesized by using fluorene as a building block for solution processable organic photovoltaics (OPVs). A variety of climatic type fluorene based NFAs by placing different donor (D) and acceptor (A) units with a structural arrangement of A-D/A-D-D/A-A were explored for OPV cells. Further several modifications in molecular backbone of the acceptors were performed by modifying central donor such as fluorene, spiro fluorene and fluorene unit fused with other aromatic ring and by revamping at π-bridge, terminal units and alkyl side chain to enhance the power generation efficiency of solar cells. This review for the most part focuses on encapsulating the simple fluorene and its derivatives core based small molecule NFAs based.

Simulation study of the tunnel junction position effect on the parameters of the InxGa1-xN dual junction solar cell

The present work presents a SILVACO-Atlas numerical simulation to investigate the effect of the tunnel junction position on the performance of InxGa1−xN double-junction solar cells under AM1.5 solar illumination. The proposed cell is composed of two PN sub-cells, an upper sub-cell in In0.1Ga0.9N and a lower sub-cell in In0.4Ga0.6N for the p-type and In0.2Ga0.8N for the n-type, connected by a tunnel junction in In0.4Ga0.6N. The cell offers a remarkable open-circuit voltage value of about 3.9 V and a good fill shape value of about 93. A cell with a small overall thickness can offer better transfer efficiency than a cell with a large thickness if the tunnel junction position is carefully chosen. The proposed cell can achieve a transfer efficiency of around 18% with an overall thickness of 0.652 μm.

(Digital Presentation) Mathematical Approximations for Monitoring the State of Charge and Computing Electrolyte Volume in Vanadium Redox Flow Battery Systems

During the last years, several attempts have been carried out to provide clean energy storage as an alternative to overcome the energy demand. Vanadium redox flow batteries (VRFBs) appear as a suitable device that converts the chemical energy present in the electrolyte into electrical energy in a noiseless and clean manner. In the mentioned device, the electrolyte is polarized by using renewable energy, and later the stored energy is used in several applications from mobile to stationary scenarios. There are two fundamental design parameters to be considered in the sizing of a VRFB: the state of charge (SoC), and the electrolyte volume. The mentioned parameters are related to two independent parameters of great importance, the energy consumption per unit of time (power delivered by the device), and the amount of energy that can be stored in the system (energy capacity).The purpose of the current study is, based on collected data and theoretical approximations, analyze the SoC and the required electrolyte volume for several applications. To estimate the SoC for the different VRFB, a Nernst-modified equation is used. In this case, the number of cells was a key part of achieving the desired results. A correction factor (λ) was introduced to visualize the trend of the generated curve family in a better manner. On the other hand, to calculate the volume of electrolyte, an equation derived from the definition of electric charge is implemented. Similarly, due to the power applications range covering the study, a correction factor (γ) was also introduced. Considering the obtained results, as the correction factor increases the load state in the system will tend to present higher values of open circuit voltage and nevertheless constant values of load state. Based on the energy capacity calculations, and considering common vanadium concentrations among the electrolytes, it was found that the higher the vanadium concentration the required electrolyte volume will tend to be minor. In addition, on a large scale, there is a greater convergence of the required electrolyte volume to values greater than 10 000 m3. Figure 1. Trend of the open circuit voltage (OCV) when the state of charge (SoC) is increasing. Due to the wide range of output power analyzed in the current study, all the OCV presented values have been determined by using a correction factor (λ). Figure 1

Design, synthesis, and performance evaluation of TiO2-dye sensitized solar cells using 2,2′-bithiophene-based co-sensitizers

We report on the synthesis and characterization of six novel 2,2′-bithiophene-based organic compounds (3a–c and 5a–c) that are designed to serve as co-sensitizers for dye-sensitized solar cells (DSSCs) based on TiO2. The compounds are linked to various donor and acceptor groups, and we confirm their chemical structures through spectral analyses. Our focus is on enhancing the performance of metal based N3, and the compounds were designed to operate at the nanoscale. We performed absorption and fluorescence emission measurements in dimethylformamide (DMF), where one of our compounds 5a exhibited the longest maximum absorption and maximum emission wavelengths, indicating the significant impact of the para methoxy group as a strong electron-donating group. Our dyes 5a + N3 (η = 7.42%) and 5c + N3 (η = 6.57%) outperformed N3 (η = 6.16%) alone, where the values of short current density (JSC) and open circuit voltage (VOC) for these two systems also improved. We also investigated the charge transfer resistance at the TiO2/dye/electrolyte interface using electrochemical impedance spectroscopy (EIS), which is important in the context of nanotechnology. According to the Nyquist plot, the 5a + N3 cocktail exhibited the lowest recombination rate, resulting in the highest VOC. Our theoretical calculations based on density functional theory (DFT) are also in agreement with the experimental process. These findings suggest that our compounds have great potential as efficient DSSC co-sensitizers. This study provides valuable insights into the design and synthesis of new organic compounds for use as co-sensitizers in DSSCs based on TiO2 and highlights the potential of these compounds for use in efficient solar energy conversion.

Formation and Characterization of Stable TiO2/CuxO-Based Solar Cells.

According to increasing demand for energy, PV cells seem to be one of the best answers for human needs. Considering features such as availability, low production costs, high stability, etc., metal oxide semiconductors (MOS) are a focus of attention for many scientists. Amongst MOS, TiO2 and CuxO seem to be promising materials for obtaining an effective photoconversion effect. In this paper, specific investigation, aimed at the manufacturing of the complete photovoltaic structure based on this concept is described in detail. A set of samples manufactured by DC magnetron sputtering, with various process parameters, is characterized by morphology comparison, layer structure and material composition investigation, and finally by the obtained photovoltaic parameters. Based on SEM studies, it was established that the films are deposited uniformly and complete their formation; without clearly defined faces, the conglomerates of the film grow individually. These are areas with a uniform structure and orientation of atoms. The sizes of conglomerates are in a normal direction range from 20 to 530 nm and increase with film thickness. The film thickness was in the range from 318 to 1654 nm, respectively. The I-V study confirms the photovoltaic behavior of thin film solar cells. The open-circuit voltage (Voc) and short-circuit current density (Jsc) values of the photovoltaic devices ranged from 1.5 to 300 mV and from 0.45 to 7.26 µA/cm3, respectively, which corresponds to the maximum efficiency at the level of 0.01%. Specific analysis of the junction operation on the basis of characteristics flow, Rs, and Rsh values is delivered.

Harvesting Bioelectricity from Microbial Fuel Cells (MFCs) Powered by Electroactive Microbes

The application of microbial fuel cells is still facing some challenges due to its low power output and high internal resistance. It is desirable to obtain a stable and consistent power output from an MFC to support practical real-world applications. Five electroactive bacteria (isolate LGf1, LGf11, LGf15, LGf20, and LGf22) isolated from the sediment of Waduk Saguling were exploited as the potential anodic biocatalyst for MFC, and the performance of these MFCs were studied in terms of voltage generation (open and close circuit), power density and the losses (polarization technique), and efficiencies (coulombic and energy). MFC biocatalyst by isolate LGf11 performed the best electrochemical performances, including highest OCV (open circuit voltage) value (804 mV) and power output (0.043 W/m2), lowest ohmic resistance (475 Ω), and highest coulombic efficiency (75.79%) and energy efficiency (88.36%) among all anodic biocatalysts. Nevertheless, all the five isolates were potential to be exploited as active biocatalyst for MFC due to their high OCV values and the stability of voltage generations, both in open circuit and close circuit mode. The development of system configuration and the use of more suitable substrate for different electroactive microbes in order to harvest more power output was recommended for further study. Utilization of these potential microbes for other applications in MFC (such as wastewater treatment etc.) was also suggested for further research. Keywords: Bio-electrochemical system, Biofuel, Efficiency, Electro-microbiology, Power output

A passivation by H2O2-TiO2 interlayer for efficient and stable Carbon-based perovskite solar cells

A major challenge of carbon-based perovskite solar cells (C-PSCs) is boosting photovoltaic performance and stability. However, their performance can be limited by undesirable increases in trap states densities and nonradiative recombination caused by defects at the interface between the perovskite and the electron transporting layer (ETL) and in the bulk perovskite. Herein, a novel passivation using H2O2-TiO2 interlayer provides an effective approach to improve the interfacial bridging between TiO2 and perovskite in C-PSCs. Additionally, the surface morphology of the HT interlayer was elaborated by varying spin coating speeds of deposition. A suitable spin coating speed was found to be 3000 rpm, called TiO2/HT-3000 ETL. This allows lower oxygen vacancy within an interfacial layer and promotes high-quality growth of perovskite film with fewer grain boundaries. TiO2/HT-3000 ETL-based C-PSCs in a homemade air-filled dry glove box achieved a PCE of 16.23%, which improved the open-circuit voltage and fill factor values. These results can be attributed to effectively reduced trap state densities and nonradiative recombination losses in the device. In addition, the newly constructed TiO2/HT-3000 ETL can notably enhance the long-term stability in ambient air without encapsulation. This simple interface passivation strategy proposes a new path toward the commercialization of perovskite solar cells.

Arsenic-Doped CdSeTe Solar Cells Achieve World Record 22.3% Efficiency

For more than three decades, Cu has been critical to dope CdSeTe solar cells, form effective contacts, and maximize efficiency. At the same time, Cu defect chemistry has limited stability, carrier concentration, and further efficiency improvements. In this article, 22.3% world record efficiency is demonstrated without Cu by implementing As doping, which also improves stability, temperature coefficient, and energy yield. The efficiency crossing point of Group V technology relative to Cu has been driven by steady improvements in the open-circuit voltage. Here, the certified record cell reaches open-circuit voltage of 899 mV while retaining high photocurrent values of 31.4 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ; the fill factor is relatively low at 78.9%. Coupling 80% fill factor with top open-circuit voltage values of 917 mV reported here offers a near-term path to 23% efficiency. Characterization indicates reducing recombination and improving activation provide viable paths to 25% efficiency.

Dye-sensitized solar cells with aluminum-doped zinc oxide nanoparticles-loaded electrolyte: A breakthrough solution for recombination and hysteresis suppression

Dye-sensitized solar cells (DSCs) suffer from reduced power conversion efficiency due to electron recombination with triiodide (I3−) ions at the photoanode/electrolyte interface. Organic additives are conventionally used in electrolyte to reduce recombination and improve the efficiency of the device. These additives react covalently with iodine (I2) in the electrolyte, leading to a reduction in the concentration of I3− ions. Other inorganic oxides, such as silica (SiO2), titania (TiO2), and magnesia (MgO), have been shown to improve the efficiency of the solar cell. These oxides can adsorb heavy ions to some extent. In this study, we investigated aluminum-doped zinc oxide nanoparticles (AZO NPs) as an inorganic additive with ionic adsorption properties towards I− and I3− anions in the electrolyte. We confirmed the ionic adsorption of AZO NPs through zeta potential and electrochemical impedance measurements. We observed a significant decrease in recombination between photogenerated electrons and electrolyte ions after adding AZO NPs, which resulted in an increase in open circuit voltage (VOC) and fill factor (FF) values. Furthermore, the incorporation of AZO NPs reduced the compelled hysteresis caused by the mismatch in current density-voltage curves for the forward and reverse scan direction. Mott-Schottky analysis confirmed the increase in VOC due to the negative shift in the Fermi level of the TiO2 photoanode. Additionally, open circuit voltage decay measurements indicated a longer electron lifetime at the TiO2/electrolyte interface in AZO NPs loaded electrolyte. Our findings suggest that AZO NPs have potential as an effective inorganic additive for improving the performance of DSCs.

Effects of Silicon Wafer’s Resistivity on Passivation and Devices Performances of Solar Cell

In the manufacture of solar cells, the resistivity of silicon wafers has a crucial impact on their performance. This study investigated the effects of different resistivities on p-TOPCon solar cells. The results indicate that lower resistivity wafers have a higher implied open-circuit voltage (iVoc) value, but higher carrier mobility due to the low resistivity leads to an increase in saturation current density (J0). Conversely, solar cells made on higher resistivity silicon wafers have a lower carrier mobility, leading to slower electron-hole recombination and lower bulk recombination, resulting in the advantage of lower saturation current density and higher minority carrier lifetime. At the same time, simulation shows that as the resistivity increases, the Voc and efficiency increase. However, cost considerations need to be taken into account as higher resistivity silicon wafers are more expensive. Therefore, resistivity between 2 - 3 Ω·cm2 is considered the preferred substrate for solar cells as it offers a better balance between cost and achieving high cell efficiency.