Effect of surface type on structural and optical properties of Ag nanoparticles formed by dewetting (original) (raw)
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Optics Express, 2013
The effects of substrates with technological interest for solar cell industry are examined on the plasmonic properties of Ag nanoparticles fabricated by dewetting technique. Both surface matching (boundary element) and propagator (finite difference time domain) methods are used in numerical simulations to describe plasmonic properties and to interpret experimental data. The uncertainty on the locations of nanoparticles by the substrate in experiment is explained by the simulations of various Ag nanoparticle configurations. The change in plasmon resonance due to the location of nanoparticles with respect to the substrate, interactions among them, their shapes, and sizes as well as dielectric properties of substrate are discussed theoretically and implications of these for the experiment are deliberated.
Applied Physics A, 2020
In this study, the surface plasmon effects of the Ag nanoparticle were investigated depending on the substrate temperature and coating time. Deposition procedure for the Ag coating was the vacuum deposition at low substrate temperature (< 300 K) instead of the commonly used the vacuum deposition at high substrate temperatures. The Ag thin films were deposited on n-type Si, glass and solar cell with safety glass substrates. The structural and optical characteristics of the Ag thin films prepared on Si and glass substrates were investigated. The Ag thin films had a polycrystalline structure with cubic phase. The (111) preferred orientation for 300 K substrate temperature was changed to (200) after 200 K substrate temperature. Homogeneous nano-sized Ag particles on Si were obtained at the 150-200 K temperature range. Optical measurements were performed for the Ag thin films prepared on glass substrates. According to reflectance measurements, plasmon resonance effect of the Ag nanoparticles was observed around 435-540 nm. The Ag nanoparticles prepared on solar cell at low substrate temperature increased the solar cell efficiency for all coating time because the nanoparticle size and shape were not changed significantly with the coating time. However, the Ag thin films prepared at high substrate temperature decreased device efficiency with the increasing coating time.
Journal of Materials Science, 2014
In this work we report on the formation of selforganized and multimodal sized patterned arrays of Au and Ag nanoparticles on SiO 2 surface exploiting the thicknessdependent solid-state dewetting properties of templateconfined deposited nanoscale films. In this approach, the Au and Ag surface pattern order, on the SiO 2 substrate, is established by the template confined deposition on a micrometric scale, while the solid-state dewetting phenomenon is induced by thermal processes (below the Au and Ag melting temperature). The deposited films have not an uniform thickness. They, instead, present a controlled thickness due to shadowing mask effects during depositions. Such an inhomogeneity can be further controlled by changing the deposition angle. After the dewetting process, scanning electron microscopy analyses allowed us to correlate the mean diameter hDi and spacing hsi of the formed nanoparticles by the thickness h of the deposited films. Despite the dewetting process of the Au and Ag films occurs in the solid state, relations describing the evolution of hDi and hsi with hhi typical of the linear hydrodynamic spinodal dewetting process of liquid films, hDi µ h 5/3 and hsi µ h 2 , were verified within a 20 % experimental error. As a consequence we call this process ''pseudo-spinodal dewetting''.
The agglomeration/dewetting process of thin silver films provides a scalable method of obtaining self-assembled nanoparticles (SANPs) for plasmonics based thin-film solar photovoltaic (PV) devices. Here, we show the effect of annealing ambiance on silver SANP average size, particle/cluster finite shape, substrate area coverage/particle distribution and how these physical parameters influence optical properties and surface-enhanced Raman scattering (SERS) responses of SANPs. Statistical analysis performed indicates that generally Ag SANPs processed in the presence of a gas (Argon and Nitrogen) ambiance tend to have smaller average size particles compared to those processed under vacuum. Optical properties are observed to be highly dependent on particle size, separation distance as well as finite shape. The greatest SERS enhancement was observed for the argon processed samples. There is a correlation between simulation and experimental data that indicate argon processed AgNPs have a great potential to enhance light coupling when integrated to thin-film PV. 1 Introduction As-deposited thin metallic films are generally metastable or unstable and readily de-wet from a solid substrate when heated even well below their melting temperature 1-2. The process of agglomeration/de-wetting proceeds in two ways: nucleation and growth of holes, and spinodal dewetting 1, 3-5. This process is a relatively economical means of obtaining both simple and complex nano-structures from thin metal films 5-10 compared to traditional methods such as e-beam lithography. Whilst dewetting during film processing has been reported to have undesirable effects on micro-and nano-systems, agglomeration has become the method of choice for catalyzed growth of nanotubes/nanowires and electronic and photonic devices 3. Dewetting of thin metallic films (both liquid and solid) to obtain mono/multi-dispersed nanoparticles has been demonstrated with a range of metals including: gold (Au), silver (Ag), nickel (Ni), copper (Cu) and alumina (Al), among others 1, 3-4, 10-1. However, Ag film dewetting has been mostly investigated as candidate for plasmonic sensing 12-18 and plasmonics-enhanced solar photovoltaics (PV) devices 19-31 applications. This is because Ag is generally considered to have the most suitable optical properties for solar cell applications. Silver nanoparticles exhibit highly intense and localized surface plasmon resonances (LSPR) and low absorption in the visible and near
Photocurrent enhancements of organic solar cells by altering dewetting of plasmonic Ag nanoparticles
Scientific reports, 2015
Incorporation of metal nanoparticles into active layers of organic solar cells is one of the promising light trapping approaches. The size of metal nanoparticles is one of key factors to strong light trapping, and the size of thermally evaporated metal nanoparticles can be tuned by either post heat treatment or surface modification of substrates. We deposited Ag nanoparticles on ITO by varying nominal thicknesses, and post annealing was carried out to increase their size in radius. PSS was employed onto the ITO substrates as a buffer layer to alter the dewetting behavior of Ag nanoparticles. The size of Ag nanoparticles on PEDOT:PSS were dramatically increased by more than three times compared to those on the ITO substrates. Organic solar cells were fabricated on the ITO and PEDOT:PSS coated ITO substrates with incorporation of those Ag nanoparticles, and their performances were compared. The photocurrents of the cells with the active layers on PEDOT:PSS with an optimal choice of th...
The preparation of thin film silicon solar cells containing Ag nanoparticles is reported in this article. Ag nanoparticles were deposited on fluorine doped tin oxide coated glass substrates by the evaporation and condensation method. a-Si:H solar cells were deposited on these substrates by cluster type plasma enhanced chemical vapor deposition. We discuss the double textured surface effect with respect to both the surface morphology of the substrate and the plasmonic effect of the Ag nanoparticles. Ag nanoparticles of various sizes from 10 to 100 nm were deposited. The haze values of the Ag embedded samples increased with increasing particle size whereas the optical transmittance decreased at the same conditions. The solar cell with the 30 nm size Ag nanoparticles showed a short circuit current density of 12.97 mA/cm 2 , which is 0.53 mA/cm 2 higher than that of the reference solar cell without Ag nanoparticles, and the highest quantum efficiency for wavelengths from 550 to 800 nm. When 30 nm size nanoparticles were employed, the conversion efficiency of the solar cell was increased from 6.195% to 6.696%. This study reports the application of the scattering effect of Ag nanoparticles for the improvement of the conversion efficiency of amorphous silicon solar cells.
Nanomaterials, 2022
Silver nanoparticles (NPs) on glass substrates were obtained by a solid-state thermal dewetting (SSD) process using vacuum-evaporated-silver precursor layers. An exhaustive investigation of the morphological, structural, and surface chemistry properties by systematically controlling the precursor film thickness, annealing temperature, and time was conducted. Thin silver films with thicknesses of 40 and 80 nm were deposited and annealed in air by applying a combined heat-up+constant temperature–time program. Temperatures from 300 to 500 °C and times from 0 to 50 min were assayed. SSD promoted the morphological modification of the films, leading to the Ag NPs having a discrete structure. The size, shape, surface density, and inter-nanoparticle distance of the nanoparticles depended on the initial film thickness, annealing temperature, and time, exhibiting a cubic silver structure with a (111) preferred crystallographic orientation. The prepared NPs were found to be highly enriched in ...
Characterization of Ag Nanocrystals for use in Solar Cell Applications
MRS Proceedings, 2009
Ag nanocrystals made by chemical synthesis have been used in solar cell applications as a part of light trapping. The shape, crystal structure, defects and composition of these nanocrystals have been studied in detail. Samples with different ratios of silver solution (AgNO 3 ) and reductant (NaBH4) were made, and a difference in nanocrystal size was observed. HRTEM and diffraction patterns showed that the samples contained mostly Ag nanocrystals, and some of them contained Ag 2 O nanocrystals as well. Some nanocrystals contained large defects, mostly twinning, which induced facets on the nanocrystal surface.
Journal of Applied Physics, 2018
We present here a study on the modification of morphological and plasmonic properties of Ag thin films deposited on glass substrates upon annealing in air at different temperatures. Initially, Ag films are continuous and exhibit extended surface plasmons with a resonant absorbance that depends on the film thickness. The dewetting process promotes the formation of nanoparticles with different sizes, shapes, and agglomerations states, besides a partial oxidation from Ag to AgO at surface level. The final Ag-AgO nanostructures are dependent on the annealing temperature and initial film thickness. The optical properties evolve from those typical of metallic films with high reflectivity and extended surface plasmon resonance toward localized surface plasmons characteristic of nanoparticles. The optical evolution and the final plasmonic response are evaluated according to the morphological and structural features of nanostructures.