Top PDF Wire array solar cells : fabrication and photoelectrochemical studies

Wire array solar cells : fabrication and photoelectrochemical studies

Wire array solar cells : fabrication and photoelectrochemical studies

Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge- carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells.
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ZnO nanosheet arrays constructed on weaved titanium wire for CdS sensitized solar cells

ZnO nanosheet arrays constructed on weaved titanium wire for CdS sensitized solar cells

present work, the power conversion efficiency of our solar cells was still not high enough for the practical applica- tions. The rather poor fill factor is considered to be the main factor limiting the energy conversion efficiency. This low fill factor may be caused by the lower hole recovery rate of the polysulfide electrolyte, which leads to a higher probability for charge recombination [21]. To further im- prove the efficiency of these nanosheet array solar cells, some new hole transport medium must be developed, one with suitable redox potential and low electron recom- bination at the semiconductor and electrolyte inter- face. Counter electrodes have also been reported to be another important factor influencing the energy conver- sion efficiency. Recently, a number of novel materials have been examined and tested as counter electrode materials; these studies prove the influence of various counter elec- trode materials on the fill factors of solar devices [22,23]. Also, the open-circuit voltage can be further improved by using more efficient combination of semiconductor nanoparticles.
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Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al doped ZnO seed layer

Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al doped ZnO seed layer

Figure 1 shows the SEM images of the SiMW arrays formed by electrochemical etching. The etching method used in this work to produce ordered arrays of the SiMW is based on the formation of porous silicon using anodic oxidation [24]. By etching a bulk Si substrate in HF elec- trolyte with electric field, Si can be etched to produce long, straight-walled, uniform pores having micrometer- sized dimensions. The pore formation in p-type Si is believed to occur through a hole-limited silicon dissolu- tion process [24]. As the applied current density increased, the macropores are gradually grown and became intercon- nected. Finally, a well-ordered array of vertical SiMWs with diamond shape appeared at the corners between the four nearest pores (Figure 1a). Full fabrication process of ordered macropores in p-type Si using HF-based solution is definitely described elsewhere [25,26]. The pore dia- meter and spacing can be controlled by the current density of the etching, the applied voltage, and the doping of the sample, while the pore length can be controlled indepen- dently by adjusting the etching time. The cross section SEM image reveals that the size of the SiMW is 1.5 μ m in diameter and 16 μm in length as shown in Figure 1b.
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Si Microwire-Array Solar Cells

Si Microwire-Array Solar Cells

In this chapter we will discuss the development of a process for the fabrication of large-area arrays of vertically aligned, nominally identical, Si microwires. There are three major reasons that a homogeneous medium of Si microwires was felt to be important for the characterization and fabrication of Si microwire arrays as a potential photovoltaic material. First, control of the wire height and diameter allows for the fabrication of wires with diameters and heights that are optimized for photovoltaic performance based upon the measured photovoltaic properties of the wires. Second, fabrication steps, such as the definition of a p-n junction, the growth of a surface passivation layer, and the deposition of a transparent top contact, are much more straightforward (as will be seen in Chapter 6) for a uniform array of wires. Third, a large distribution of wire heights and diameters will lead to a distribution in each wire’s voltage at its maximum power point.[16] As the wires will be connected in parallel in a wire-array solar cell and as the wire-array solar cell must operate at a single voltage, a distribution in the wire height and diameter will result in a fraction of wires that operate away from their maximum power point. Thus, a wire-array solar cell with a large variation in wire heights and diameters will be inherently inefficient. The fabrication of nominally identical, vertically aligned, Si microwires was ac- complished through the use of the vapor-liquid-solid (VLS) growth mechanism. Pho- tolithography was used to pattern an array of VLS-catalysts (Au, Cu or Ni) onto a Si(111) wafer. VLS-growth using SiCl 4 as a Si precursor at 1000 ◦ C was then used
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Optical simulations of P3HT/Si nanowire array hybrid solar cells

Optical simulations of P3HT/Si nanowire array hybrid solar cells

30 scientific publications in journals and conference proceedings related to micro and nano systems. LW got his Ph.D. degree in Condensed Matter Physics in Solid State Physics in 2013 at Hefei Institute of Physical Science, Chinese Academy of Sciences. At present, he has a post-doctoral position at the Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences. He is involved in semiconductor device design and characterization of nanowires and nanoparticles of both polymeric and inorganic materials for photovoltaic applications. YZ obtained his bachelors degree in Applied Physics from China University of Petroleum in 2011. Now, he studies Solid State Physics at Hefei Institute of Physical Science, Chinese Academy of Sciences for his master's degree. What he majors in are synthesis and characterization of III-V compound semiconductor nanowires and photovoltaic applications. HD received her bachelors degree in Applied Physics in 2012 at Changchun University of Science and Technology, China. At present, she is working on fabrication and characterization of semiconductor nanostructure-based applications at Solid State Physics at Hefei Institute of Physical Science, Chinese Academy of Sciences for a master's degree. BZ obtained his master's degree in The Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, in 2013. At present, he studies at the Solid State Physics Department at Hefei Institute of Physical Science, Chinese Academy of Sciences for a Ph.D. degree. He majors in the synthesis and characterization of semiconductor materials and semiconductor devices. TS received his Ph.D. degree at the Department of Physics of the University of Science and Technology of China in 2007. And now, he is a research associate at the Institute of Solid State Physics, Chinese Academy of Sciences. He has a background in X-ray absorption spectrum, polymer solar cells, and thin films coatings. XZ obtained his bachelors degree in Materials Science and Engineering in 2009 at Nanjing University, China. Now, he stays at Solid State Physics Department at Hefei Institute of Physical Science, China Academy of Sciences for a Ph.D. degree. He is working on fabrication and characterization of polymer semiconductor nanostructure. NL received his bachelors degree in Applied Physics in 2011 at Anhui University, China. At present, he is working on fabrication and characterization of polymer semiconductor at Solid State Physics Department at Hefei Institute of Physical Science, Chinese Academy of Sciences for his master's degree. YW obtained his Ph.D. degree from Columbia University in 1993. Now, he is a professor in Solid State Physics at Hefei Institute of Physical Science, Chinese Academy of Sciences. His research interests are wide-gap semiconductor materials, novel semiconductor devices, and semiconductor quantum structures.
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Theoretical analysis of GaAs/AlGaAs quantum dots in quantum wire array for intermediate band solar cell

Theoretical analysis of GaAs/AlGaAs quantum dots in quantum wire array for intermediate band solar cell

great number of material combinations have been employed to fabricate IBSCs. Among them, self-assembled InAs quantum dot (QD) arrays fabricated by molecular beam epitaxy (MBE) have been widely studied as a building block to create the IB in the GaAs host material. However, the band gap combination and the location of IB in InAs/GaAs QD based IBSCs is not favourable and the upper limit efficiency is around 20% (1 sun) and 34% (1000 suns). 3–7 In order to improve the IBSC efficiency, host materials with much wider band gap such as AlGaAs or GaP are required. Recently, we have succeeded in the fabrication of GaAs QD arrays embedded in AlGaAs quantum-wire (QWR) host material by using a combination of neutral beam etching and atomic hydrogen-assisted MBE regrowth. 8 This top-down lithography and etching method is a strain-free approach, with the advantages of being able to precisely control the size, spacing, and arrangement of the QD during growth, which is difficult to achieve by self-assembling growth. In this study, we performed theoretical simulation of GaAs/AlGaAs QD arrays using a combined multi band k p and drift-diffusion transport method. The electronic structure, IB band dispersion, and optical transitions, including absorp- tion and spontaneous emission among the VB, IB, and CB, were calculated. Based on these pa- rameters, the theoretical conversion efficiency limit of GaAs/AlGaAs QD array based IBSC devices were calculated by a drift-diffusion model adapted to IBSC. 9–11
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A. Solar PV Array

A. Solar PV Array

PV systems are most widely used renewable energy sources (RES) now a days which possess numerous advantages. These advantages includes locally available generation, high efficiency, less maintenance and minimal environmental impact. Grid integration of SPV power generation systems at the grid side enhance the generation and also create adverse effects such as voltage limit violation, frequency fluctuation, grid instability etc. [1-3]. Grid connected SPV array must follow the codes and regulations of grid defined by the IEEE 1547, IEC 61727 and VDE-AR-N4105. Inverter control in a grid integrated mode of SPV power generation system plays very important role to synchronizing it with grid. Numerous control approaches for grid synchronization and integration of SPV power generation system are widely available in literature [4-7].
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SYSTEMATIC DESIGN, FABRICATION AND EXPERIMENTAL STUDIES ON SOLAR THERMAL WATER PUMP

SYSTEMATIC DESIGN, FABRICATION AND EXPERIMENTAL STUDIES ON SOLAR THERMAL WATER PUMP

The solar thermal pump is a good option where electrical power is not available and solar energy is in plenty. The design of the solar pump which entailed detailed calculations to obtain the optimal volumes of vessels and experimentation on the fabricated set up are presented in this paper. The pump employs ethyl ether as the working substance which is an organic fluid with a low boiling point. The flat plate solar collector of area 1 m 2 generates vapour and its pressure is adequate to pump water from a well. The inclusion of storage tank for vapour and a separate condenser facilitates greater freedom in the pump’s operation and thereby improved performance. The performance of solar water pump has been analyzed for three different discharge heads 3, 4 and 5 m with a maximum efficiency of 0.14 x10 -2 .
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Fabrication of cadmium sulfide and cadmium telluride solar cells and their characterisations

Fabrication of cadmium sulfide and cadmium telluride solar cells and their characterisations

About 66% of the world electrical power provide by fossil fuels, and world's total energy demands about 95%. As worldwide requirement of energy is more than supply, due to this reason the total cost of suppling electricity becomes expensive. Due to use these fossil such as, coal, gas and oil the global warming and climate have been changed. Also using of fossil fuels to produce electricity and transportation vehicles products carbon dioxide, sulphur and nitrogen oxide leads to acide rain. Hence, it is necessary to look for clean, efficient and sustainable form energy source. The solar energy is one of the most important significant renewable source of energy, which is abundant. The sun is continual source of light and heat. About 5,000,000 tons of energy per second emits from the sun in gama ray. All these rays move to the ground's surface, some of them is absorbed and some of them re- emitted towards universe. The total energy radiate from the sun toward the earth about 98% within 0.25μm to 3μm wavelength (Bapanapalli, 2005).
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Deposition and characterization of bi2s3 for photoelectrochemical solar cell application

Deposition and characterization of bi2s3 for photoelectrochemical solar cell application

demonstrated by Ahire and Sharma (2006) and Mane et al., (1999). The heating of the PEC cells by the tungsten lamp was prevented by interposing a water filter between them. The intensity of the illumination was measured by Lux meter and found to be at 80mW/cm 2 . The spectral response of the cell was recorded using monochromator in the wavelength range of 350nm-1050nm. Transient photo response and Capacitance- Voltage (C-V) characteristics of the cell were used to calculate other photo electrochemical properties of the cell.

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Plasmon Enhanced Light Absorption in GaAs Nanowire Array Solar Cells

Plasmon Enhanced Light Absorption in GaAs Nanowire Array Solar Cells

electrode effectively. The wavelength-dependent com- plex refractive index used to describe the material dis- persion properties of GaAs can be obtained from the study of Levinshtein et al. [19]. By applying periodic boundary conditions in the x and y directions, the simu- lations are carried out within this unit cell to model the periodic NWA structure. The simulation domain is closed at the top and bottom with a perfectly matched layer, allowing reflected light and transmission light to escape the simulation volume. The incident light from the top is set in parallel to the NW axis as indicated in Fig. 1a, and we use a plane wave defined with power intensity and wavelength values from a discretized AM 1.5G solar spectrum with a wavelength ranging from 290 to 900 nm (typical absorption region of GaAs) to model the sunlight. The reflection monitor is located at above the top surface of the NWA, and the transmission monitor is located at the bottom surface of substrate to calculate the light absorbed. The amount of power trans- mitted through the power monitors is normalized to the source power at each wavelength. The reflectance R (λ) and transmission T (λ) are calculated by the equation
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Photoelectrochemical studies of nonstoichiometric nanostructured PbOx

Photoelectrochemical studies of nonstoichiometric nanostructured PbOx

Taking all these in to consideration, here in this study we have explored the possibilities of a potential pulse anodization of Pb metal. To start with the optimization the potential pulse anodization with different combinations of step potentials in the range of anodic peaks were applied for different time at 80 C. The potential pulse position, pulse width, interval time and duty cycle, were optimized and it was found that the electrode anodized from a potential pulse between 0.6 to 0.1 V (pulse structure as shown in Figure-2) for 800 s gives the best photoresponse. Hence the subsequence studies were carried out for the best photo electrode.
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Fabrication of one dimensional photonic crystals by photoelectrochemical etching of silicon

Fabrication of one dimensional photonic crystals by photoelectrochemical etching of silicon

Abstract—The conditions of formation of deep periodic trenches by photoelectrochemical etching of nSi (100) with linear seeds on the surface are analyzed. Criteria for the proper choice of the period of seed grooves and the etching current density in relation to the doping level of the substrate are formulated. Corrugation of walls is a characteristic feature of the obtained structures; this corrugation is caused by traces of merged macropores. Atomicforce microscopy is used to study roughness of the sidewalls in relation to the etching conditions; the current density at which one can obtain the smoothest sidewalls is determined. The rough ness of the side walls in structures with periods of 7 and 9 μ m on Si with the resistivity of 15 Ω cm amounts to ~40 nm. It is shown that additional treatment of the structures in alkaline solutions can decrease the sidewall roughness by approximately a factor of 2.
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Controlled fabrication of Sn/TiO2 nanorods for photoelectrochemical water splitting

Controlled fabrication of Sn/TiO2 nanorods for photoelectrochemical water splitting

To measure the performance of photoelectrochemical (PEC) water splitting, the exposed FTO was covered with a layer of silver paste and connected to Cu wires with solder. The silver paste, solder, edge and some part of the film were sealed with polydimethylsiloxane (PDMS) or epoxy, in which only a well-defined area about 1 cm 2 of the white film was exposed to the elec- trolyte. A glass vessel filled with 400 mL 1 M KOH was used as the PEC cell, and a class AAA solar simulator (Oriel 94043A, Newport Corporation, Irvine, CA, USA) with the light intensity of 100 mW/cm 2 was used as light source. The photocurrent and electrochemical imped- ance spectra were collected by electrochemical station (AUTOLAB PGSTAT302N, Metrohm Autolab, Utrecht, The Netherlands). Line sweep voltammograms were ob- tained at the scan rate of 20 mV/S. A Pt slice acting as the counter electrode and a standard Ag/AgCl reference electrode (containing saturated KCl solution) were used for the PEC measurements. The water splitting process in PEC cell was schematically illustrated in (Additional file 1: Figure S1).
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Silicon Concentrator Solar Cells: Fabrication, Characterization and Development of Innovative Designs

Silicon Concentrator Solar Cells: Fabrication, Characterization and Development of Innovative Designs

Carrier lifetime instabilities in boron-doped silicon solar cells under illumination have been extensively investigated in the past and several distinct phenomena have been reported. One of the effects most frequently investigated is the degradation of the carrier lifetime as a consequence of illumination in boron-doped Cz silicon [70]. This effect was explained with presence under light exposition of boron-oxygen defects: lifetime reducing recombination centers, made up of one interstitial boron and one interstitial oxygen atom, are created under illumination. The effect was observed only in Cz silicon and never in FZ silicon, because large concentrations of oxygen are practically unavoidable in Cz silicon due to the partial dissolution of the silica crucible during the growth process. In fact, the experiments showed that gallium-doped and phosphorus-doped Cz silicon as well as oxygen-free FZ silicon samples did not present any lifetime degradation effect, which is thus ex- clusively linked to the simultaneous presence of boron and oxygen in the material [71]. Many experiments show that the light-induced lifetime degradation effect due to the boron-oxygen defects is fully reversible only by means of thermal annealing above 200 ◦ C [70][72][73].
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Photoelectrochemical Studies at CdS/PTTh Nanoparticles Interfaces

Photoelectrochemical Studies at CdS/PTTh Nanoparticles Interfaces

All electrochemical experiments were carried out using a conventional three electrode cell consisting of Pt wire as a counter electrode, a Ag/AgCl as a reference electrode, and Pt Gauze as an electron collector. A BAS 100 W electrochemical analyzer (Bioanalytical Co.) was used to perform the electrochemical studies. Steady state reflec- tance spectra were performed using Shimadzu UV-2101 PC. Irradiation was performed with a solar simulator 300 watt xenon lamp (Newport) with an IR filter.

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Fabrication and characterisation of high efficiency inverted P3HT:PCBM polymer solar cells

Fabrication and characterisation of high efficiency inverted P3HT:PCBM polymer solar cells

Among many photovoltaic (PV) technologies polymer-fullerene based inverted bulk heterojunction (BHJ) solar cells have drawn lot attention in recent years due to low cost fabrication over a large area by using simple solution-processed methods. This thesis presents a study o f inverted organic solar cells (OSCs) on indium tin oxide (ITO) coated glasses and metal substrates using spin coating technique. Zinc oxide (ZnO) and poly(3,4- ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) were used as the electron transport layer (ETL) and hole transport layer (HTL) respectively. Poly(3- hexylthiophene):[ 6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM ) was used as an active layer. The ZnO layers deposited using nanoparticles (NPs) and sol-gel route at a temperature o f 150 °C. The poor wettability o f aqueous PEDOT:PSS on the hydrophobic P3HT:PCBM layer was improved with the addition o f surfactant Triton X-100. The P3HT:PCBM photoactive layer was optimised in terms o f solvents, concentrations and layer thickness. However, the thickness o f the active layer in BHJ devices need to be very thin (~ 200 nm) which causes poor light absorption and low carrier mobilities. Therefore, it is important to introduce new approaches to enhance the photon absorption efficiency o f the active layer under the film thickness limitation. Among all the approaches plasmonic nanostructures have recently emerged as an expanding area to enhance light absorption in organic photovoltaic (OPV) devices.
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Fabrication and investigation of the optoelectrical properties of MoS2/CdS heterojunction solar cells

Fabrication and investigation of the optoelectrical properties of MoS2/CdS heterojunction solar cells

measured the electrical properties of the solar cells, and wrote the manuscript. FY, CW, YZ, and MS investigated the surface morphologies, structures, and electrical and optical properties of the samples and participated in the analysis of the results of the solar cells. XM designed the structure of the solar cell and analyzed the results. All authors read and approved the final manuscript.

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Efficiency improvement of silicon solar cells enabled by ZnO nanowhisker array coating

Efficiency improvement of silicon solar cells enabled by ZnO nanowhisker array coating

laser deposition [21], chemical vapor deposition [22], vapor–liquid-solid growth [23], hydrothermal method [24], and electrochemical deposition technique [25]. Among them, a seeding and growth two-step process in zinc salt and amide mixed solutions seems quite accept- able for photovoltaics due to its low cost and good po- tential for scale-up [26,27]. Experiments have shown that ZnO nanorod arrays can exhibit better antireflec- tive properties than other oxide compounds [28]. A weighted global reflectance of 6.6% has been achieved in the broadband range from 400 to 1,200 nm [29]. How- ever, most work on ZnO nanorod arrays as antireflective layers is performed on the naked silicon wafer by now [29,30]. The application of ZnO nanostructures in the practical silicon solar cells is seldom reported.
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Fabrication of High-Efficiency Silicon Solar Cells by Ion Implant Process

Fabrication of High-Efficiency Silicon Solar Cells by Ion Implant Process

This study investigated a novel production method of ion-implanted emitter formation for high- efficiency silicon photovoltaic cells. This innovation increased absolute cell efficiency by 0.5% on solar CZ grade wafer, and enabled a simplified process flow by eliminating the need for the PSG strip and junction isolation stages. Due to precise dopant control by the ion implant tool, the Rsheet uniformity of the implant process is greater than that of thermal POCl 3 diffusion. After annealing, the

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