Nanoparticles In Solar Cells Research Articles

A comparative study of Cu2ZnSn(SxSe1−x)4 nanoparticles for solar cells: From chemical synthesis to devices

Thin-film solar cells using quaternary compounds Cu2ZnSn(SxSe1−x)4 (0 ≤ x ≤ 1; CZTSe, CZTSSe, or CZTS) as absorber materials have attracted a lot of attention from the photovoltaic research community. Traditionally, vacuum-based techniques have been used for the synthesis of Cu2ZnSn(SxSe1−x)4 absorbers. In this work, an easy, less toxic, non-vacuum, single-reaction chemical route is used for the synthesis of Cu2ZnSn(SxSe1−x)4 (x = 0.0,0.4,1.0) nanoparticles. Using structural characterization techniques, the presence of kesterite phase in the as-synthesised nanoparticles is confirmed. The surface micrographs revealed increase in nanoparticle grain size with the selenium doping and nearly stoichiometric composition with compact morphology of nanoparticles. Further, the optical characterization of as-synthesised nanoparticles exhibited bandgaps in the range 1.52 – 1.02 eV which are optimal for thin film solar cell applications. The fabricated solar cells using synthesised compounds exhibited promising photo response capabilities with a highest efficiency of 0.752% for Cu2ZnSn(S0.4Se0.6)4 absorber-based device under AM1.5 illumination without any buffer layer. Results presented in this work indicate the suitability of the kesterite compounds synthesized through the chemical route as absorber materials for cheap solar cells.

Design and analysis of multi-layer silicon nanoparticle solar cells

We investigate the concept of nanoparticle-based solar cells composed of a silicon nanoparticle stack as a light trapping absorber for ultrathin photovoltaics. We study the potential of using these inherently nanotextured structures in enhancing the light absorption. For this, a detailed optical analysis is performed on dependency of the cell response to parameters such as the number of particle layers, lattice structure and angle of incidence; Optical response of these cells are then compared with the results in conventional silicon solar cells. Moreover, we propose various configurations to apply these submicron particles as a p–n junction solar cell. We also compute the electrical performance of selected configurations. In doing so, key issues including the effect of contact points between nanoparticles and impact of loss are addressed. In the end, we show how mathrm{SiO}_2 nanoparticles on top of the cell structure can enhance the photocurrent. The appropriate range of mathrm{SiO}_2 particle size is also obtained for the typical cell structures.

Using the Electrode Potential to Orient Single Molecules in Nanoscale Electrical Junctions and Determine Charge Transport Mechanism

Charge transport through and between molecules is central to important processes in nature. Studying the conductivity of single molecules can contribute to a better understanding of charge transport, and also help to develop building blocks of molecular electronics, light harvesting devices, etc. We measure the conductivity of molecules using the Scanning Tunneling Microscope break-junction (STM-BJ) method that utilizes repeatedly formed circuits where one or a few molecules are trapped between two electrodes, at least one of which has nanoscale dimensions. The statistical analysis of thousands of measurements yields the conductance of single molecules.One particular interest is the role of the molecule-electrode contact and orientation in charge transport. In the simplest analysis this contact can present a substantial barrier to charge injection, which can have important consequences in devices such as dye sensitized semiconductor nanoparticle solar cells. Our most recent developments include controlling the orientation of the molecule in the junction using the electrode potential so that we can measure conductance along different molecular axes, accessing elements of the anisotropy of the molecular conductance tensor. Specifically, when the molecule is oriented flat, with the molecular plane parallel to the electrode surface, charge transport is measured perpendicular to the molecular plane. Furthermore, the electrode dependence of the molecular conductivity provides insight into the transport mechanism. This approach can be applied to molecules that do not have suitable molecular anchoring groups for traditional STM-BJ measurements, and allows us to determine the importance of anchoring groups in charge transport in molecular junctions.

Hierarchical carrier transport simulator for defected nanoparticle solids

The efficiency of nanoparticle (NP) solar cells has grown impressively in recent years, exceeding 16%. However, the carrier mobility in NP solar cells, and in other optoelectronic applications remains low, thus critically limiting their performance. Therefore, carrier transport in NP solids needs to be better understood to further improve the overall efficiency of NP solar cell technology. However, it is technically challenging to simulate experimental scale samples, as physical processes from atomic to mesoscopic scales all crucially impact transport. To rise to this challenge, here we report the development of TRIDENS: the Transport in Defected Nanoparticle Solids Simulator, that adds three more hierarchical layers to our previously developed HINTS code for nanoparticle solar cells. In TRIDENS, we first introduced planar defects, such as twin planes and grain boundaries into individual NP SLs superlattices (SLs) that comprised the order of 103 NPs. Then we used HINTS to simulate the transport across tens of thousands of defected NP SLs, and constructed the distribution of the NP SL mobilities with planar defects. Second, the defected NP SLs were assembled into a resistor network with more than 104 NP SLs, thus representing about 107 individual NPs. Finally, the TRIDENS results were analyzed by finite size scaling to explore whether the percolation transition, separating the phase where the low mobility defected NP SLs percolate, from the phase where the high mobility undefected NP SLs percolate drives a low-mobility-to-highmobility transport crossover that can be extrapolated to genuinely macroscopic length scales. For the theoretical description, we adapted the Efros-Shklovskii bimodal mobility distribution percolation model. We demonstrated that the ES bimodal theory’s two-variable scaling function is an effective tool to quantitatively characterize this low-mobility-to-high-mobility transport crossover.

Investigation of the Use of Titanium Dioxide Nanoparticles in Solar Cells

Today, nanoparticles have attracted the attention of many researchers due to their special properties as well as their many technological applications. Among these, titanium dioxide nanoparticles have many important applications in various industries due to their excellent optical, electrical and catalytic properties. These applications include use in industrial pigments, as photocatalysts in environmental cleansing, in sunscreens to protect the skin, in photovoltaic applications for solar cells, sensors, in electronic device components, and many more. Two important properties of this material that make it very efficient and useful in life are its photocatalytic and superhydrophobic properties. These two properties are used to purify water and wastewater, eliminate air pollution and buildings, accelerate photochemical reactions such as hydrogen production, fabricate surfaces and layers and self-cleaning glass. The properties of titanium dioxide nanoparticles are strongly dependent on the size of the doped particles, elements or compounds and the surface modifications made on them, which in turn are influenced by the nanoparticle synthesis method. For this reason, methods for the synthesis of titanium dioxide nanoparticles have received much attention today. As the size of the material gets smaller and smaller and reaches the nanoscale, new physical and chemical properties show up. Among the unique properties of nanomaterials, the motion of electrons and holes in semiconductor nanomaterials is dominated by quantum constraint, and the transfer properties of phonons and photons are strongly influenced by the size and geometry of the material. The effective surface area and surface to volume ratio increase with decreasing the material size. High effective levels are achieved by small particles, which will be useful in many 2TiO-based types of equipment in which the interaction of the common surface of the material is important.

Investigation of The Use of Titanium Dioxide Nanoparticles in Solar Cells

Today, nanoparticles have attracted the attention of many researchers due to their special properties as well as their many technological applications. Among these, titanium dioxide nanoparticles have many important applications in various industries due to their excellent optical, electrical and catalytic properties. These applications include use in industrial pigments, as photocatalysts in environmental cleansing, in sunscreens to protect the skin, in photovoltaic applications for solar cells, sensors, in electronic device components, and many more. Two important properties of this material that make it very efficient and useful in life are its photocatalytic and superhydrophobic properties. These two properties are used to purify water and wastewater, eliminate air pollution and buildings, accelerate photochemical reactions such as hydrogen production, fabricate surfaces and layers and self-cleaning glass. The properties of titanium dioxide nanoparticles are strongly dependent on the size of the doped particles, elements or compounds and the surface modifications made on them, which in turn are influenced by the nanoparticle synthesis method. For this reason, methods for the synthesis of titanium dioxide nanoparticles have received much attention today. As the size of the material gets smaller and smaller and reaches the nanoscale, new physical and chemical properties show up. Among the unique properties of nanomaterials, the motion of electrons and holes in semiconductor nanomaterials is dominated by quantum constraint, and the transfer properties of phonons and photons are strongly influenced by the size and geometry of the material. The effective surface area and surface to volume ratio increase with decreasing the material size. High effective levels are achieved by small particles, which will be useful in many 2TiO-based types of equipment in which the interaction of the common surface of the material is important.

Impact of Ag doping on structural, optical, morphological, optical and photoluminescent properties of ZnO nanoparticles

An investigation of room-temperature sol–gel synthesis Ag doped ZnO nano-particles are reported here. The effect of silver concentration (2, 4, 6, 8 and 10 at. wt.%) on the morphology, structural and optical properties of the Ag doped ZnO nanoparticles are studied. XRD analysis displays the hexagonal wurtzite structure. The crystallite size was found to decrease in the range 36.95–28.11 nm with the increase in Ag dopant percentage. With enhancement in the Ag contents, the crystallite size decreases and specific surface area increases which suggest their use in biological science and photocatalysis. Surface morphology shows that grains are irregular, cuboid, linear and spherical shaped nanoparticles with slightly varying sizes. The Ag doped ZnO nanoparticles show interesting properties, which are modified by the change of the grain size with increase in Ag dopant percentage. The band gap of the nanoparticles decreases with increase in Ag doping where 10 at. wt.% Ag dopant nanoparticles have a notably lower band gap than that of undoped ZnO (3.37 eV). Photoluminescence spectra has shown the violet shift emission bands. The optical properties predict the use of Ag doped ZnO nanoparticles in solar cells, optoelectronics, spintronics and wastewater treatment.

Using the Electrode Potential to Orient Single Molecules in Nanoscale Electrical Junctions

Charge transport through and between molecules is central to important processes in nature. Studying the conductivity of single molecules can contribute to a better understanding of charge transport, and also help to develop building blocks of molecular electronics, light harvesting devices, etc. We measure the conductivity of molecules using the Scanning Tunneling Microscope break-junction (STM-BJ) method that utilizes repeatedly formed circuits where one or a few molecules are trapped between two electrodes, at least one of which has nanoscale dimensions. The statistical analysis of thousands of measurements yields the conductance of single molecules.One particular interest is the role of the molecule-electrode contact and orientation in charge transport. In the simplest analysis this contact can present a substantial barrier to charge injection, which can have important consequences in devices such as dye sensitized semiconductor nanoparticle solar cells. Our most recent developments include controlling the orientation of the molecule in the junction using the electrode potential so that we can measure conductance along different molecular axes, accessing elements of the anisotropy of the molecular conductance tensor. Specifically, when the molecule is oriented flat, with the molecular plane parallel to the electrode surface, charge transport is measured perpendicular to the molecular plane. This approach can be applied to molecules that do not have suitable molecular anchoring groups for traditional STM-BJ measurements, and allows us to determine the importance of anchoring groups in charge transport in molecular junctions.

Bacterial Synthesis of Ternary CdSAg Quantum Dots through Cation Exchange: Tuning the Composition and Properties of Biological Nanoparticles for Bioimaging and Photovoltaic Applications.

In this study, we introduce a biological method for the production of ternary Quantum Dots (QDs): complex nanostructures with tunable optical and structural properties that utilizes post-synthesis modifications through cation exchange. This versatile in-situ cation exchange method being reported for the first time shows great potential for extending the scope of microbial synthesis. By using this bacterial-based method, we easily synthesize and purify CdS, CdSAg, and Ag2S nanocrystals of a size below 15 nm and with variable morphologies that exhibit fluorescence emissions covering a broad spectral range (from 400 to 800 nm). Energy-dispersive X-ray spectroscopy (EDS) results indicate the partial replacement of Cd2+ by Ag+ when AgNO3 concentration is increased. This replacement produces CdSAg ternary QDs hetero-structures with high stability, fluorescence in the NIR-I (700 - 800 nm), and 36.13% quantum yield. Furthermore, this reaction can be extended for the production of soluble Ag2S nanoparticles (NPs) without any traces of Cd. QDs biosynthesized through this cation exchange process display very low toxicity when tested in bacterial or human cell lines. Biosynthesized ternary hetero-structures were used as red fluorescent dyes to label HeLa cells in confocal microscopy studies, which validates its use in bioimaging applications in the near infrared region. In addition, the application of biologically-produced cadmium NPs in solar cells is reported for the first time. The three biosynthesized QDs were successfully used as photosensitizers, where the CdSAg QDs show the best photovoltaic parameters. Altogether, obtained results validate the use of bacterial cells for the controlled production of nanomaterials with properties that allow their application in diverse technologies. We developed a simple biological process for obtaining tunable Quantum Dots (QDs) with different metal compositions through a cation exchange process. Nanoparticles (NPs) are produced in the extracellular space of bacterial cells exposed to cysteine and CdCl2 in a reaction that depends on S2− generation mediated by cysteine desulfhydrase enzymes and uses cellular biomolecules to stabilize the nanoparticle. Using this extracellular approach, water-soluble fluorescent CdS, CdSAg, and Ag2S Quantum Dots with a tunable emission ranging from 400 to 800 nm were generated. This is the first study reporting the use of microorganisms to produce tunable ternary QDs and the first time that a cation exchange process mediated by cells is described. Obtained results validate the use of biological synthesis to produce NPs with new characteristics and opens a completely new research field related to the use of microorganisms to synthesize complex NPs that are difficult to obtain with regular chemical methods.

Study of functional coatings based on polyvinyl butyral and silver nanoparticles for solar cells

Study of functional coatings based on polyvinyl butyral and silver nanoparticles for solar cells

Synthesis of binary Cu-Se and In-Se nanoparticle inks using cherry blossom gum for CuInSe2 thin film solar cell applications

Selenium (Se)-rich binary Cu-Se and In-Se nanoparticles (NPs) were synthesized by a modified heat-up method at low temperature (110 °C) using the gum exudates from a cherry blossom tree. Coating of CISe absorber layer was carried out using Se-rich binary Cu-Se and In-Se NPs ink without the use of any external binder. Our results indicated that the gum used in the synthesis played beneficial roles such as reducing and capping agent. In addition, the gum also served as a natural binder in the coating of CISe absorber layer. The CISe absorber layer was integrated into the solar cell, which showed a power conversion efficiency (PCE) of 0.37%. The possible reasons for low PCE of the present solar cells and the steps needed for further improvement of PCE were discussed. Although the obtained PCE is low, the present strategy opens a new path for the fabrication of eco-friendly CISe NPs solar cell by a relatively chief non-vacuum method.

High performance hybrid silicon micropillar solar cell based on light trapping characteristics of Cu nanoparticles

High performance silicon combined structure (micropillar with Cu nanoparticles) solar cell has been synthesized from N-type silicon substrates based on the micropillar array. The combined structure solar cell exhibited higher short circuit current rather than the silicon miropillar solar cell, which the parameters of micropillar array are the same. Due to the Cu nanoparticles were decorated on the surface of silicon micropillar array, the photovoltaic properties of cells have been improved. In addition, the optimal efficiency of 11.5% was measured for the combined structure solar cell, which is better than the silicon micropillar cell.

Potential for improved transport in core–shell CuInS2 nanoparticle solar cells from an Ag surface termination

Improvements in charge carrier transport and equivalent photoluminescence were obtained for CuInS2 nanoparticles with Ag-surface termination in photovoltaic devices.

Functionalization of MWCNT by plasma treatment and use as additives for non-vacuum CuIn(S, Se) 2 nanoparticle deposition solar cells

Abstract The effects of MWCNT incorporation into non-vacuum chalcopyrite nanoparticle deposition solar cells were investigated in this study. To improve MWCNT dispersion within CuIn(S, Se) 2 nanoparticle ink, MWCNT were grafted with maleic anhydride (MA) via plasma treatment. The functional groups on the surface of MWCNT were characterized by X-ray photoelectron spectroscopy. The grafting level of MA on MWCNT was 18.6 wt%. A series of CuIn(S, Se) 2 nanoparticle solar cells with various weight ratios (wt%) of MWCNT-MA were fabricated. The structure of grounded CuIn(S, Se) 2 nanoparticles was verified by transmission electron microscopy and X-ray diffraction analysis. The band gap energy of CuIn(S, Se) 2 nanoparticles was obtained by UV–vis-NIR spectrophotometer. Scanning electronic microscopy showed that MWCNT–MA at ≤0.5 wt% dispersed well within CuIn(S, Se) 2 nanoparticles. At 0.33 wt%, MWCNT-MA facilitated 15% increase in conversion efficiency of solution-based CuIn(S, Se) 2 nanoparticle solar cells by increasing carrier transfer efficiency, and thus, increasing current density J sc .

Eco-friendly fabrication of PBDTTPD:PC71BM solar cells reaching a PCE of 3.8% using water-based nanoparticle dispersions

In this work we report on the eco-friendly processing of PBDTTPD:PC71BM organic solar cells using water-based nanoparticle (NP) dispersions. The polymer:fullerene NPs are prepared using the miniemulsion-solvent evaporation method, despite employing high-boiling solvents. Polymer solar cells are fabricated from these blend NPs and the device characteristics are studied in function of annealing time and temperature. The photoactive layer formation is carefully analyzed using atomic force microscopy (AFM). Annealing for longer times significantly increases the power conversion efficiency (PCE), up to 3.8%, the highest value reported for surfactant based NP solar cells. Our work shows that the low bandgap polymer PBDTTPD has the ability to afford reasonable efficiencies in NP solar cells in combination with PC71BM and paves the way to a truly eco-friendly processing of organic photovoltaics (OPVs).

Tuning of PCDTBT:PC71BM blend nanoparticles for eco-friendly processing of polymer solar cells

We report the controlled preparation of water processable nanoparticles (NPs) employing the push-pull polymer PCDTBT and the fullerene acceptor PC71BM in order to enable solar cell processing using eco-friendly solvent (i.e. water). The presented method provides the possibility to separate the formation of the active layer blend and the deposition of the active layer into two different processes. For the first time, the benefits of aqueous processability for the high-potential class of push-pull polymers, generally requiring high boiling solvents, are made accessible. With our method we demonstrate excellent control over the blend stoichiometry and efficient mixing. Furthermore, we provide visualization of the nanomorphology of the different NPs to obtain structural information down to ~2nm resolution using advanced analytical electron microscopy. The imaging directly reveals very small compositional demixing in the PCDTBT:PC71BM blend NPs, in the size range of about <5nm, indicating fine mixing at the molecular level. The suitability of the proposed methodology and materials towards the aspects of eco-friendly processing of organic solar cells is demonstrated through a processing of lab scale NPs solar cell prototypes reaching a power conversion efficiency of 1.9%.

Design and analysis of multilayer waveguides containing nanoparticles for solar cells

A novel waveguide structure containing nanoparticles with various substrate media has been proposed to find out the transmission and reflections of the incident light on the proposed structure. The Transfer matrix method has been applied to study the transverse electric TE and the transverse magnetic TM waves at an Antireflection (AR) coating structure for silicon solar cells with a nanoparticles-dielectric layer. The transmission and reflection coefficients have been derived at different incident angles of light and for various substrate’s materials in wavelength region between 300nm and 1200nm. The numerical results, obtained by MAPLE software, highlight an enhancement of the transmission coefficient and reduction of the reflections for different substrate media.

Synthesis of ligand-free CZTS nanoparticles via a facile hot injection route

Single-phase, ligand-free Cu2ZnSnS4 (CZTS) nanoparticles that can be dispersed in polar solvents are desirable for thin film solar cell fabrication, since water can be used as the solvent for the nanoparticle ink. In this work, ligand-free nanoparticles were synthesized using a simple hot injection method and the precursor concentration in the reaction medium was tuned to control the final product. The as-synthesized nanoparticles were characterized using various techniques, and were found to have a near-stoichiometric composition and a phase-pure kesterite crystal structure. No secondary phases were detected with Raman spectroscopy or scanning transmission electron microscopy energy dispersive x-ray spectroscopy. Furthermore, high resolution transmission electron microscopy showed large-sized nanoparticles with an average diameter of 23 nm ± 11 nm. This approach avoids all organic materials and toxic solvents that otherwise could hinder grain growth and limit the deposition techniques. In addition the synthesis route presented here results in nanoparticles of a large size compared to other ligand-free CZTS nanoparticles, due to the high boiling point of the solvents selected. Large particle size in CZTS nanoparticle solar cells may lead to a promising device performance. The results obtained demonstrate the suitability of the synthesized nanoparticles for application in low cost thin film solar cells.

Design principle for absorption enhancement with nanoparticles in thin-film silicon solar cells

The use of nanoparticles in solar cells has created many controversies. In this paper, different mechanisms of nanoparticles with different materials with diameters varying from 50 to 200 nm, surface coverage at 5, 20, and 60 %, and different locations are analyzed systematically for efficient light trapping in a thin-film c-Si solar cell. Mie theory and the finite difference time domain method are used for analysis to give a design principle with nanoparticles for the solar cell application. Metals exhibit plasmonic resonances and angular scattering, while dielectrics show anti-reflection and scattering in the incident direction. A table is given to summarize the advantages and disadvantages in different conditions. The silicon absorption enhancement with nanoparticles on top is mainly in the shorter wavelengths below 700 nm, and both Al and SiO2 nanoparticles with diameter around 100 nm show the most significant enhancement. The silicon absorption enhancement with embedded nanoparticles takes place in the longer wavelengths over 700 nm, and Ag and SiO2 nanoparticles with larger diameter around 200 nm perform better. However, the light absorbed by Ag nanoparticles will be converted to heat and will lead to decrease in cell efficiency; hence, the choice of metallic nanoparticles in applications to solar cells should be carefully considered. The design principle proposed in this work gives a guideline by choosing reasonable parameters for the different requirements in the application of thin-film solar cells.

Synthesis of Anatase and Rutile TiO&lt;sub&gt;2&lt;/sub&gt; Crystals for High-Performance Dye-Sensitized Solar Cells

TiO2 nanosize particles have attracted significant interest of materials scientists and physicists due to their special properties and have attained a great importance in several technological applications such as photocatalysis, sensors, solar cells and memory devices. TiO2 nanoparticles can be produced by a variety of techniques ranging from simple chemical to mechanical to vacuum methods, including many variants of physical and chemical vapour deposition techniques. In the present research work we report the synthesis of TiO2 nanoparticles by Sol-Gel technique. The characterization of particles was carried out by XRD and SEM techniques. The importance and applications of these nanoparticles for solar cells are also discussed in this work. Recently, the importance of tailored particles has been recognized in a number of applications such as solar cells and photonic crystals. Among the many metal oxides and their inorganic-organic hybrid materials used for the above applications, one of the most important and complex in this regard is titanium dioxide (titania). In this study, the processing parameters in an alkoxide free sol-gel synthesis of anatase titania nanoparticles were investigated. Factors affecting the sol-gel process include the reactivity of inorganic titanium salt, calcinations temperature, the influence of varying stirrer speeds on the formation of anatase particles, and the nature of hydrolytic solvent and peptisation reagent. By varying these processing parameters, materials with different microstructure and surface chemistry can be obtained.