Generation Photovoltaic Cells Research Articles

Honeycomb shaped carbon dopped 1T-2H-MoS2 heterojunction counter electrode with high short current for dye sensitized solar cells

Recent years have witnessed energy crises in various regions and the utilization of new energy is crucial. Dye-sensitized solar cells (DSSCs) are the third generation of photovoltaic cells that are expected to be more cost-effective than other types of solar cells. In this work, we report the synthesis of 1T-2H-MoS2/honeycomb shaped carbon (HSC) heterojunction composite counter electrodes for DSSCs via adding porous carbon in the facile hydrothermal method. The effects of HSC on the morphology, structure, electrochemical and photoelectric conversion properties of the 1T-2H-MoS2/HSC composites were investigated systematically. Both the results of electrochemical and photoelectric measurement suggest the excellent performance of the reduction of I3- and the regeneration of dye. The whole cell assembled with the MoS2/HSC-5.0 counter electrode achieved a short current density 22.24 mA∙cm−2 and a power conversion efficiency (PCE) of 8.42 %, which is significantly higher than that of the pure MoS2 electrode (5.89 %) and Platinum electrode (6.76 %), implying the MoS2/HSC-5.0 composite is a promising candidate for counter electrodes catalyst of DSSCs.

Photovoltaic Cell Generation and Recent Advancements in Its Development

Photovoltaic Cell Generation and Recent Advancements in Its Development

Optoelectric characteristics of PVC/SrxZnO nanocomposite films

Poly(Vinyl)Chloride (PVC) films modified by SrxZnO nanoparticles (NPs) were prepared by a simple casting method utilizing its solution in tetrahydrofuran (THF). The PVC films contained 5 wt% of SrxZnO NPs. SrxZnO particles with 0.00, 0.025, 0.05, 0.075 and 0.1 Sr-doping levels were synthesized by the sol-gel method associated with a hydrothermal process. The PVC/SrxZnO films were characterized by XRD, FTIR, Raman, SEM, UV–Visible and PL spectroscopy. XRD analysis demonstrated that SrxZnO into PVC matric are well crystallized in the hexagonal ZnO structure with wurtzite phase, while PVC is in an amorphous state. The particle sizes of SrxZnO vary in the range of 17–31 nm in agreement with the Sr levels. The ATR and Raman spectroscopy verified the existence of a Zn–O bond related to the wurtzite phase. The SEM cross-section views of the films revealed the bulk nature as well as the thicknesses. Strong emission at 733 nm is observed from the PL analysis, associated with Sr content in the PVC/SrxZnO films. Reflectivity, transmittance, and absorption coefficient confirmed the contribution of the physics developed by SrxZnO NPs into the PVC matrix. Urback energies are Sr-level dependent, as a consequence of defects tailoring. Optical transitions (directly and indirectly allowed) decrease in some cases by close to 1 eV indicating a transition of PVC to a semi-crystalline material. Other optical properties including linear and nonlinear characteristics promoted PVC/SrxZnO as a serious candidate for antireflective coating, and a new generation of photovoltaic cells.

Synergistic effect on silicon surface under low energy he ion irradiation at elevated temperatures

One of the major challenges in nuclear fusion, nanolithography, and various industries is the effect of low energy ion irradiation on the surface morphology of materials. For example, the effect of low energy irradiation on plasma-facing materials' lifetime in fusion reactors, the effect on the optical systems in nanolithography laser produced plasma devices, and the effect on mass production of effective and flexible anti-reflecting coatings in photovoltaic (PV) industry. Silicon and carbides in particular, showed interest in nuclear fusion as potential wall materials, as in mirror designs for nanolithography devices, and as coatings in PV system components. Recently innovative novel Si nanostructures such as nanocones (NCs) demonstrated great feasibility in several areas including the next generation PV cells, batteries, supercapacitors, nano-optoelectronics, photonics, and energy storage devices. Their unique electronic properties and significantly higher absorption over a wide broadband range, offer paramount potential in various fields including microelectronics, optoelectronics, photonics, photovoltaics, biology, sensors, templet for selective growth (on nanostructured substrates), fast electronic devices, and even in high- density data storage. We tailor Si NCs using simultaneous low energy helium (He) ion irradiation on planar Si (111) and (100) and Ta metal masks. In a series of successive experiments, three key parameters, temperature, flux, and presence of Ta metal impurity, were tuned to study the progression of nanostructure development, as well as the effect of these nanostructures on key material properties. Before performing He ion sputtering experiments, 100 eV Ar+ ion irradiations, for 10 min duration, were also performed in-situ in each case for removing any preexisting SiO2 form planer Si substrates. Clear and distinctive progressions of NC development were found during the tuning of each parameter. During the temperature dependent studies, we clearly observed a sequential progression from thicker and less dense cones (773 K) to finer and more densely packed NCs (1073 K). On the other hand, during the case of flux dependent studies, it was found that increasing flux increases the size of the NCs, with low flux resulting in sparsely placed nanodots, and high fluxes resulting in large conglomerates. Finally, the effect of Ta impurity shows an increased propensity for NCs development. In addition, using optical-reflectivity studies we clearly observed a significant reduction (from ∼65 to almost zero) in optical reflectivity.

Intelligent Systems and Photovoltaic Cells Empowered Topologically by Sudoku Networks

A graph invariant is a number that can be easily and uniquely calculated through a graph. Recently, part of mathematical graph invariants has been portrayed and utilized for relationship examination. Nevertheless, no reliable appraisal has been embraced to pick, how much these invariants are associated with a network graph in interconnection networks of various fields of computer science, physics, and chemistry. In this paper, the study talks about sudoku networks will be networks of fractal nature having some applications in computer science like sudoku puzzle game, intelligent systems, Local area network (LAN) development and parallel processors interconnections, music composition creation, physics like power generation interconnections, Photovoltaic (PV) cells and chemistry, synthesis of chemical compounds. These networks are generally utilized in disorder, fractals, recursive groupings, and complex frameworks. Our outcomes are the normal speculations of currently accessible outcomes for specific classes of such kinds of networks of two unmistakable sorts with two invariants K-banhatti sombor (KBSO) invariants, Irregularity sombor (ISO) index, Contraharmonic-quadratic invariants (CQIs) and dharwad invariants with their reduced forms. The study solved the Sudoku network used in mentioned systems to improve the performance and find irregularities present in them. The calculated outcomes can be utilized for the modeling, scalability, introduction of new architectures of sudoku puzzle games, intelligent systems, PV cells, interconnection networks, chemical compounds, and extremely huge scope in very large-scale integrated circuits (VLSI) of processors.

Narrow bandgap ferroelectric [KNbO3](1-x)-[BaCo1/2Nb1/2O3-δ]x solid solution for bulk photovoltaic cell

We report a stable bulk photovoltaic effect in [KNbO3]0.9-[BaCo1/2Nb1/2O3–δ]0.1 (KBCNO-91) solid solution as a result of the light-induced electric field in the orthorhombic phase of KBCNO. Introducing Ba2+ and Co3+ ions in the host lattice of perovskite solid solution, the bandgap can be tuned from 3.2 to 1.59 eV. A photovoltaic cell consists of a 43 nm thin KBCNO-91 perovskite oxide semiconductor sandwiched between the metal electrodes evoke open-circuit voltage (VOC) of >1.9 V, above the bandgap with short-circuit current of ∼1 nA at no external bias (0 V). The fabrication of a two-dimensional ferroelectric solid solution semiconductor with a narrow bandgap of ∼1.59 eV enables the conversion of visible photons into electrical energy in a compact electrode configuration. The device retains its stability for over one year and is expected to be a potential candidate for the next generation of photovoltaic cells.

Photovoltaic Cell Generations and Current Research Directions for Their Development.

The purpose of this paper is to discuss the different generations of photovoltaic cells and current research directions focusing on their development and manufacturing technologies. The introduction describes the importance of photovoltaics in the context of environmental protection, as well as the elimination of fossil sources. It then focuses on presenting the known generations of photovoltaic cells to date, mainly in terms of the achievable solar-to-electric conversion efficiencies, as well as the technology for their manufacture. In particular, the third generation of photovoltaic cells and recent trends in its field, including multi-junction cells and cells with intermediate energy levels in the forbidden band of silicon, are discussed. We also present the latest developments in photovoltaic cell manufacturing technology, using the fourth-generation graphene-based photovoltaic cells as an example. An extensive review of the world literature led us to the conclusion that, despite the appearance of newer types of photovoltaic cells, silicon cells still have the largest market share, and research into ways to improve their efficiency is still relevant.

Silicon-Tin Alloyed Nanocrystals by Femtosecond Laser Plasma

Silicon’s (Si) indirect bandgap limits its absorption and possible applications, and therefore remarkable efforts are put into the possibility of fabricating a material compatible with the existing silicon technology that is also a direct bandgap material. Tin (Sn) alloying with silicon represents an exciting possibility to tune Si properties. In addition, at the quantum confinement size (<10 nm) when the material becomes a quantum dot, it becomes possible to control the electronic structure of a material by varying the size. Although the possibility to tailor the bandgap of elemental Si over a wide range has been demonstrated, it is very challenging to obtain stable alloyed SiSn quantum dots. In particular, alfa Sn has a crystal structure similar to Si with zero band gap: a diamond cubic crystal structure, and importantly affected by the crystal configuration and a possible change to a direct energy gap at sufficiently high Sn concentration. This therefore makes Sn a favorable element to create an alloy with a lower bandgap than Si. Exploiting these features would make alloyed SiSn NCs an important candidate for a broad range of applications such as next generation photovoltaic cells based on carrier multiplication, super high efficient photodetectors, fluorescent tags for biomedical applications etc. In this contribution we will discuss the synthesis paths and optoelectrical properties in the context of silicon, tin, and silicon/tin alloyed nanocrystals at high alloying concentrations. Our results show that plasma-based processes allow the synthesis of alfa tin alloyed SiSn QDs with unprecedented dimensions and alloying concentrations. We will present SiSn-QDs as the world’s highest alloys fabricated by confined plasma from femtosecond (fs) laser in liquid media with a high tin concentration of approximately 17% ever reported in literature to our knowledge. We have demonstrated for the first time the experimental and exact theoretical calculation determination of the thermal stability of the SiSn-NCs at those concentrations. We study their electronic properties by means of an approximate band structure suitable for finite-sized systems (quasi-band structure) derived from first-principles calculations. This work therefore advances the current state of the art, provides opportunities to compare and verify theoretical results and offer important directions for applications.

Methodological Foundations for Modeling the Processes of Combining Organic Fuel Generation Systems and Photovoltaic Cells into a Single Energy Technology Complex

The needs to reduce the imperfection of theoretical and methodological approaches to value and regulate the processes of applying the methods of transactional energy are substantiated. The concept of combining organizational, economic and mathematical models to improve technical, technological and information methods for the effective integration of renewable and traditional energy facilities has been formulated. This determined the goal of forming a digital platform for machine-to-machine automatic processing of transactions. The creation of the platform contributes to solving a number of research tasks including development of schemes for the use of photo and thermoelements for energy generation in distributed energy and control of electrical and thermodynamic parameters of equipment in sensors of its diagnostics and use in electric drives of actuators of the Industrial Internet of Things. The use of big datа and datа science tools is aimed at achieving a number of practical results. Firstly, the differentiation of the composition of capacities and sources in the complex of hybrid energy facilities has been expanded, secondly, possibilities of modeling has been increased. Furthermore, the results of investigation are the model of integration and balancing regulation in the transactional energy platform of the Center for the Coordination of Interest in Complex Objects.

Engineering silicon-carbide quantum dots for third generation photovoltaic cells.

Interested in the recent development of the building up of photovoltaic devices using graphene-like quantum dots as a novel electron acceptor; we study in this work the optoelectronic properties of edge-functionalized SiC quantum dots using the first principles density functional. For an accurate quantitative estimation of key parameters, a many-body perturbation theory within GW approximation is also performmed. We examine the ability to tailor the electronic gap and optical absorption of the new class of QDs through hydroxylation and carboxylation of seam atoms, in order to improve their photovoltaic efficiency. The HOMO-LUMO energy gap was significantly altered in terms of the type, the concentration and the position of functional groups. The spatial charge separation and charge transfer characterizing our systems seem very prominent to use as dye-sensitized solar cells. Furthermore, the optical band gap of all our compounds is in the NIR-visible energy window, and exhibits a magnitude smaller than that calculated in the pristine case, which enhances the photovoltaic efficiency. Likewise, absorption curves, exciton binding energy and singlet-triplet energy splitting have been broadly modified by functionalization confirming the great luminescent yield of SiCQDs. Depending on the size, SiC quantum dots absorb light from the visible to the near-infrared region of the solar spectrum, making them suitable for third generation solar cells.

Synthesis and characterization of novel conjugated copolymers for application in third generation photovoltaic solar cells

An organic photovoltaic cell (OPV) is a subcategory of the third generation of photovoltaic cells. Advantages of OPV include lightness and ease of production in industrial scale. This work proposes the synthesis and characterization of two novel random and block copolymers for OPV containing fluorene (F), thiophene (T) and benzothidiazole (B) as structural units. Polymerizations were performed via the Suzuki-Miyaura mechanism. The yields obtained for both copolymers were around 65% with corresponding molar masses measured by GPC of 3394 and 4598 g/mol. From TGA, the onset degradation temperature was approximately 415 °C, while the maximum degradation temperature was around 440 °C, for both copolymers. FTIR and NMR analyses confirmed the ratio of aliphatic and aromatic carbons in the structure of both copolymers. Difference of chaining between both copolymers was verified by 13CNMR and XRD. The energy values of HOMO were -5.76 eV for random and -5.74 eV for block copolymer. Through UV-Vis spectroscopy, optical bandgaps of 2.39 and 2.34 eV were obtained for random and block polymers, respectively. Finally, LUMO energy levels of -3.37 eV (random) and -3.40 eV (block) were calculated by subtracting the optical band gap from the HOMO energy. Mobility measurements by JV method were performed in pure polymer films, rendering 1.91 × 10−6 and 1.35 × 10-8 cm2 /V.s for random and block copolymers, respectively. Copolymers were applied in conventional and inverted devices, presenting diode behavior. Energy efficiency obtained was higher for the block copolymer, which was consistent with the obtained interplanar distances estimated by XRD.

A Database for Urdu Text Detection and Recognition in Natural Scene Images

Conventional solar cells are not economical and are recently too expensive to the manufacturers for extensive-scale electricity generation. Cost and efficiency is most vital factor in the accomplishment of any solar technology. In order to improve the conversion efficiency, the major research in third generation photovoltaic (PV) cells is directed toward retaining more sunlight using nanotechnology. Advancement in nanotechnology solar cell via quantum dots (QDs) could reduce the cost of PV cell and additionally enhance cell conversion efficiency. Silicon quantum dots (Si-QDs) are semiconductor nano crystals of nanometers dimension whose electron-holes are confined in all three spatial dimensions. Quantum dots have discrete electronic states. Quantum dots have capacity to change band gap with the adjustment in size of quantum dot. As the quantum dots size fluctuates over a wide range that demonstrates the variety of band gap so it will assimilate or discharge light. In this paper, the generic mathematical models of PV cell are adopted and then I-V and P-V characteristic curves are obtained from selected parameters using MATLAB software. The essential parameters are taken from datasheets. I-V and P-V characteristics curves are obtained for selected model. Silicon quantum dots have the tunable band gap that is added to conventional PV cell and obtain the I-V and P-V curves. After simulation, efficiency and power of Conventional PV cell to quantum dots based PV cell is compared. The property of quantum dots is used in extending the band gap of solar cells and increasing the maximum proportion of incident sunlight absorbed, hence improving efficiency.

Third generation photovoltaic cells based on photonic crystals

The structural design, physical mechanism and device performance of third-generation photovoltaic cells based on photonic crystals were reviewed.

STUDY ON OPTICAL PROPERTIES OF GRAPHENE-TIO2 NANOCOMPOSITE AS PHOTOANODES LAYER IN DYE SENSITIZED SOLAR CELL (DSSC)

Dye Sensitized Solar Cell (DSSC) using titanium dioxide (TiO2) has begun to play a significant role in future solar energy since it is known as cost effective and highly efficient. DSSC is the third generation of photovoltaic cells that have been widely investigated as a promising replacement of current commercial solar cell. However, the highest efficiency of DSSC still has not achieved the minimum requirement so that it can be commercialize. Much research has been done to improve DSSC performance by focusing on photoanodes layer. In this study, graphene was employed into TiO2 photoanode to increase the efficiency and to enhance the performance of dye sensitized solar cell. Four different samples of nanocomposites paste were prepared by varying the graphene composition of 0.00, 0.30, 0.50 and 0.70 wt%. The prepared samples were coated on Fluorine-Doped Tin Oxide (FTO) conductive glass substrates by a doctor blade method and annealed at 450oC for 30 minutes. The morphology and structure of the graphene-TiO2 nanocomposites layer were characterized by using Field Emission Scanning Electron Microscope (FESEM). The optical properties were studied by using UV-visible spectroscopy. Based on the result show that addition of graphene into TiO2 have provide larger surface area compared to pure TiO2. The optical properties of Graphene-TiO2 nanocomposites also improved as the fundamental of absorption edge has shifted toward longer wavelength and reduce the optical band gap.

Electronic properties of surface/bulk iodine defects of CsSnBr3 perovskite

Perovskites are one of a few semiconducting materials that have been shaping the progress of the third generation photovoltaic cells. The power conversion efficiency of the perovskite solar cell has been certified as 20.1% in 2015. In this work, CsSnBr3 perovskite has been considered as an alternative material for solar cell applications because of its appropriate band gap. The study has focused on the influence of iodine impurity on the electronic properties of CsSnBr3 perovskite modeled on the (001) surface structures. The crystal structures and the electronic properties have been calculated using density functional theory (DFT) within a plane wave pseudopotential framework. The GW method has been also employed to obtain more accurate band gaps. The results show that the iodine defect improves the efficiency of photo absorbance in perovskite solar cell by lowering its energy gap. In particular, the iodine bulk defect in the SnBr2-terminated surface structure was found to exhibit the narrowest band gap. This result suggests that iodine impurity deep into the structure, e.g. iodine-dopant created from high-energy implantation, plays an important role to improve the efficiency of light absorption in CsSnBr3 perovskite.

Transparent quasi-solid state dye-sensitized solar cells sensitized with naturally derived pigment extracted from red seaweed

Red seaweeds collected at Kefallinia Greek Island are examined for the first time as possible sensitizers in third generation photovoltaic cells. In particular, red seaweeds were collected and different solvents were used to extract their pigment through a simple procedure, in order to be used as a natural sensitizer for dye-sensitized solar cells. The dye solution with enhanced absorption in the visible spectrum was submitted to further absorption tests, where different pH and dye solution's temperature were tested to determine whether it affects the amount of the adsorbed dye on nanocrystalline TiO2 films. Solutions made with natural dye extracted from red algae in different solvents were used for the sensitization of TiO2 photoanodes and fabrication of quasi-solid state dye-sensitized solar cells some of which exhibited very satisfactory results compared with the published values so far of other seaweed dyes. The solar cells were examined in terms of J–V characteristic curves under simulated solar illumination and the best performing ones were also tested under dark conditions, while electrochemical impedance spectroscopy was used to evaluate electrodes and electrolyte interfaces. The optimal results were obtained for an acidic dye solution (pH = 3) and for pigment's solution temperature of 35 °C where cells showed a short circuit current density of 1.26 mA/cm2 and an open-circuit voltage of 0.66 V.

Nanoporous TiO2 electrode grown by laser ablation of titanium in air at atmospheric pressure and room temperature

Recently, fabrication of the nanoporous TiO2 photoelectrode on metal foils by means of sputtering of the Ti film on preheated metal substrate followed by the TiO2 deposition (doctor blade technique) and sintering represents the frequently applied technique. This is despite the relatively complicated procedure and number of parameters to be controlled in order to fabricate films of required properties. In this work an approach is applied and discussed in which the nanoporous TiO2 electrode is fabricated under conditions similar to pulsed laser deposition but with the deposit formed directly on the ablated target at atmospheric pressure and room temperature. The titanium dioxide thin film is grown by ablation of the Ti foil with the nanosecond UV laser (266nm) at fluence up to 1.5J/cm2. The rutile–anatase phase transformation takes place during this one-step process and no thermal pre-and post-treatment of the deposit is needed. In samples produced in air, the presence of mixed phases of the non-stoichiometric anatase (>70%), rutile and negligible amount of TiN is consistently confirmed by the X-ray diffraction, energy-dispersive X-ray and Raman spectra. For applications of the reported films as electrode material in the third generation photovoltaic cells, the use of industrial lasers could significantly improve the process efficiency.

Cluster Preface: In Memory of Professor Manfred Schlosser

Alessandro Mordini was born in Florence, Italy. He graduated in chemistry at the University of Florence in 1983 (Prof. Alfredo Ricci) and obtained his PhD degree at the same University in 1987 with the same supervisor. He held post-doctoral positions at Lausanne University, Switzerland (Prof. Manfred Schlosser) in 1986, 1989, and 1992. In 1987, he was appointed Researcher at CNR in Florence. Since 1999 he is Senior Researcher at the Institute of Organometallic Compounds (CNR-ICCOM) Sesto Fiorentino, Italy. In 2001, he was visiting professor at the University of Kyoto, Japan. His research interest is in synthetic organic chemistry, especially in the field of carbanionic species (polar organometallics, metal-mediated rearrangements). More recent activities focus on the design and synthesis of new organic sensitizers for third generation photovoltaic cells. Victor Snieckus was born in Lithuania and fled with his parents to Germany during World War II. He obtained the B.Sc. at the University of Alberta, graduate degrees at University of California, Berkeley (D. S. Noyce) and University of Oregon (V. Boekelheide), and carried out postdoctoral studies at NRC Ottawa (O. E. Edwards). He taught at the University of Waterloo until 1998, then moved to Queen’s University, Kingston as the inaugural Bader Chair of Organic Chemistry. He continues fundamental research as Bader Chair Emeritus as well as Director of Snieckus Innovations, an institute for the synthesis of small molecules for the pharmaceutical and agrochemical industries. He is a recipient of the ACS Cope Scholar Award, Arfvedson-Schlenk-Prize of the GDCh, CSC Bernard Belleau Award, and is a Lithuanian Academy of Sciences Laureate. He infrequently plays hockey and wishes he had not given up the clarinet.

Improving Energy Conversion Efficiency of Dye-Sensitized Solar Cells by Modifying TiO2 Photoanodes with Nitrogen-Reduced Graphene Oxide

As potential third generation photovoltaic cells, dye-sensitized solar cells (DSSCs) have attracted extensive research interests and have become one of the hot topics in current research. In this work, a series of DSSCs based on TiO2 photoanodes modified by graphene oxide (GO) and nitrogen-reduced graphene oxide (N-rGO) were fabricated. Results indicate that N-rGO is a better TiO2 photoanode modifier of DSSCs compared to GO. With an increase in the amount of N-rGO, the open circuit voltage increases, while both the short circuit current and power conversion efficiency (PCE) of the DSSCs exhibit a maximum at the content of 0.2 wt % N-rGO. In particular, the maximum PCE of the DSSCs reaches 7.19% in this work, which gains a 13.23% enhancement compared to the PCE of 6.42% of conventional TiO2 DSSCs. The enhancement of the PCE of the DSSCs with N-rGO was mainly attributed to the reduction in electron recombination and the increase in electron transfer efficiency after incorporating N-rGO into TiO2 photoanodes.

DFT study of electronic and structural properties of Sm:GaN

First principle calculations of Sm:GaN carried out using GGA-PBE, mBJ and GGA+U are presented to demonstrate the structural, electronic and magnetic properties of the system. The effects of Hubbard correction (i.e. U) on band structure and location of Sm 4f levels are discussed in detail. The application of U indicated a considerable splitting of occupied and unoccupied 4f band unlike that of GGA and mBJ. The introduction of Sm related gap states caused narrowing of band gap which is expected to facilitate the tuning of optical transitions. The results also indicated the production of intermediate bands in the band gap of host material which points to possible use of this material in photovoltaic cell generation. The observed spin polarization of 4f and 5d and 6s states of Sm shows possibility of ferromagnetic exchange interactions in the material for spintronic devices.