CORONENE ORGANIC FILMS: OPTICAL AND SPECTRAL CHARACTERISTICS UNDER ANNEALING TEMPERATURE INFLUENCES

2021 ◽  
pp. 2150081
Author(s):  
ERMAN ERDOGAN
Keyword(s):  
Refractive Index ◽  
Annealing Temperature ◽  
Film Growth ◽  
Low Cost ◽  
Spectral Characteristics ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Optical Bandgap ◽  
Dielectric Constants ◽  
Optical Parameters

In this study, spin coating, which is a chemical film layer thin film deposition method, was used for coronene films that were grown on Si substrates annealed at 325, 350 and 375[Formula: see text]K to examine the impacts on the optical properties of films. This method allows for easy control of the deposition parameters such as concentration, temperature and time as well as enables the film growth at low cost. Optical (UV–Vis) spectral measurements in the wavelength range from 200[Formula: see text]nm to 800[Formula: see text]nm were used to extract the bandgap information and to calculate various optical parameters of the spin-coated coronene films. The electronic transitions on the absorption of photons of suitable energy are of indirect allowed type. The corresponding optical bandgap ([Formula: see text]) was determined. Complex dielectric constants, dissipation factor, optical and electrical conductances and refractive index of coronene films were analyzed as a function of temperature. As the film annealing temperature was increased, the dielectric constants and the refractive index values increased, whereas the optical bandgap and electrical and optical conductivity values decreased.

scholarly journals A FRACTAL MODEL FOR THE FIRST STAGES OF THIN FILM GROWTH

Fractals ◽  
1996 ◽  
Vol 04 (03) ◽  
pp. 321-329 ◽  
Author(s):  
PABLO JENSEN ◽  
ALBERT-LÁSZLÓ BARABÁSI ◽  
HERNÁN LARRALDE ◽  
SHLOMO HAVLIN ◽  
H. EUGENE STANLEY
Keyword(s):  
Thin Film ◽  
Film Growth ◽  
Dynamical Evolution ◽  
Thin Film Deposition ◽  
Fractal Model ◽  
Film Deposition ◽  
Thin Film Growth ◽  
Small Cluster ◽  
Diffusion Controlled ◽  
Cluster Diffusion

In this paper, we briefly review a model that describes the diffusion-controlled aggregation exhibited by particles as they are deposited on a surface. This model allows us to understand many experiments of thin film deposition. In the Sec. 1, we describe the model, which incorporates deposition, particle and cluster diffusion, and aggregation. In Sec. 2, we study the dynamical evolution of the model. Finally, we analyze the effects of small cluster mobility and show that the introduction of cluster diffusion dramatically affects the dynamics of film growth. Some of these effects can be tested experimentally.

scholarly journals Bias Stress in Organic Thin-Film Transistors Towards Low-Cost Flexible Gas Sensors

2021 ◽  
Vol 16 (2) ◽  
pp. 1-11
Author(s):  
José Enrique Eirez Izquierdo ◽  
José Diogo da Silva Oliveira ◽  
Vinicius Augusto Machado Nogueira ◽  
Dennis Cabrera García ◽  
Marco Roberto Cavallari ◽  
...  
Keyword(s):  
Thin Film ◽  
Flexible Electronics ◽  
Thin Film Transistors ◽  
Low Cost ◽  
Thin Film Deposition ◽  
Dielectric Surface ◽  
Organic Thin Film Transistors ◽  
Film Deposition ◽  
Organic Thin Film ◽  
Bias Stress

This work is focused on the bias stress (BS) effects in Organic Thin-Film Transistors (OTFTs) from poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14) on both highly-doped Si and glass substrates. While the former had a thermally-grown SiO2 dielectric, the latter demanded an alternative dielectric that should be capable to withstand bottom contact lithography, as well as semiconducting thin-film deposition. In addition, it should represent one more step towards flexible electronics. In order to do that, poly(4-vinylphenol) (PVP) was blended to poly(melamine-co-formaldehyde) methylated (PMF). OTFTs on glass with a cross-linked polymer dielectric had a charge carrier mobility (μ) of 4.0x10-4 cm2/Vs, threshold voltage (VT) of 18 V, current modulation (ION/OFF) higher than 1x102, and subthreshold slope (SS) of -7.7 V/dec. A negative BS shifted VT towards negative values and produced an increase in ION/OFF. A positive BS, on the other hand, produced the opposite effect only for OTFTs on Si. This is believed to be due to a higher trapping at the PVP:PMF interface with PBTTT-C14. Modeling the device current along time by a stretched exponential provided shorter time constants of ca. 105 s and higher exponents of 0.7–0.9 for devices on glass. Due to the presence of increased BS effects, the application of organic TFTs based on PVP:PMF as flexible sensors will require compensating circuits, lower voltages or less measurements in time. Alternatively, BS effects could be reduced by a dielectric surface treatment.

Thin Film Deposition and Growth Processes by Ionized Cluster Beams

1990 ◽  
Vol 206 ◽  
Author(s):  
I. Yamada ◽  
G.H. Takaoka ◽  
H. Usui ◽  
S.K. Koh
Keyword(s):  
Thin Film ◽  
Cluster Size ◽  
Molecular Beam ◽  
Film Growth ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Atomic Scale ◽  
Cluster Beam ◽  
Film Nucleation ◽  
Cluster Beams

ABSTRACTAtomic scale imaging by STM and TEM of the initial stages of film growth of Ag and Au on graphite substrates indicate that the film nucleation processes are markedly different for ionized cluster beam (ICB) and molecular beam (MBE) deposition. Recent results on measurements of cluster size and formation of epitaxial metal-semiconductor layers by ICB are also discussed.

Sol-Gel Pzt Films for Optical Waveguides

1991 ◽  
Vol 243 ◽  
Author(s):  
S.L. Swartz ◽  
S.D. Ramamurthi ◽  
J. R. Busch ◽  
V.E. Wood
Keyword(s):  
Refractive Index ◽  
Optical Waveguides ◽  
Sol Gel ◽  
Optical Loss ◽  
Ferroelectric Thin Film ◽  
Thin Film Deposition ◽  
Optical Quality ◽  
Film Deposition ◽  
Pzt Films ◽  
Degree Of Orientation

AbstractSol-gel processing is a candidate ferroelectric thin-film deposition method for electronic and electro-optic applications. At Battelle, sol-gel PbTiO3 and Pb(Zr,Ti)O3 films have been prepared on sapphire and single-crystal SrTiO3 substrates. Films deposited and annealed on sapphire substrates are crystalline with the perovksite structure and minimal crystallographic orientation, whereas films deposited on isostructural and lattice-matched SrTiO3 substrates exhibit a high degree of orientation. Guided-mode refractive index measurements were made using a single-prism method and film indices were computed. Refractive index values measured for PbTiO3 films (n = 2.58) and PZT films (n = 2.50) were slightly lower than values expected on the basis of bulk measurements. In double-prism experiments, optical wavcguiding was achieved over distances up to 10 mm in oriented PZT films on [100] SrTiO3substrates. Optical loss of 19 dB/cm was measured on one of these film samples. Such films, given requisite improvement in optical quality, may be suitable for useful optical waveguide devices. An approach is presented for the integration of ferroelectric waveguides onto silicon and/or GaAs substrates.

Effect of Annealing Temperature on the Optical Parameters of CdS Thin Films Prepared by Thermal Evaporation Method

2013 ◽  
Vol 747 ◽  
pp. 329-332
Author(s):  
Thitinai Gaewdang ◽  
Ngamnit Wongcharoen ◽  
Tiparatana Wongcharoen
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Annealing Temperature ◽  
Thermal Evaporation ◽  
Optical Parameters ◽  
Spectral Transmission ◽  
Dispersion Energy ◽  
Thermal Evaporation Method ◽  
Transmission Data ◽  
Cds Thin Films

CdS thin films were prepared by thermal evaporation onto glass substrate in vacuum better than 5.5x10-5 mbar. The obtained films were subsequently annealed in a pure nitrogen atmosphere at temperature between 100 to 500°C for 30 min. The crystal structure and surface morphology of the as-deposited and annealed films were investigated by XRD and SEM, respectively. Optical band gap and Urbach tail values of the films, determined from spectral transmission data, were found to be slightly varied in the range 2.36-2.40 eV and 110-160 meV, respectively, due to annealing temperature. The refractive index of the films was also evaluated from the spectral transmission data. The dependence of the refractive index on the wavelength obeys the single oscillator model, from which the important parameters such as refractive index, extinction coefficient, oscillator energy (E0) and dispersion energy (Ed) of the films with different annealing temperatures were determined. From the experimental results, the optical parameters of the films are obviously influenced by annealing temperature.

scholarly journals Methylammonium Lead Tri-Iodide Perovskite Solar Cells with Varying Equimolar Concentrations of Perovskite Precursors

2021 ◽  
Vol 11 (24) ◽  
pp. 11689
Author(s):  
Mritunjaya Parashar ◽  
Anupama B. Kaul
Keyword(s):  
Solar Cells ◽  
Low Cost ◽  
Perovskite Solar Cells ◽  
Thin Film Deposition ◽  
Solvent Mixture ◽  
Film Deposition ◽  
Solution Processing ◽  
Lead Iodide ◽  
Deposition Processes ◽  
Power Point

During recent years, power conversion efficiencies (PCEs) of organic-inorganic halide perovskite solar cells (PSCs) have shown remarkable progress. The emergence of various thin film deposition processes to produce perovskite films, notably using solution processing techniques, can be credited in part for this achievement. The engineering of chemical precursors using solution processing routes is a powerful approach for enabling low-cost and scalable solar fabrication processes. In the present study, we have conducted a systematic study to tune the equimolar precursor ratio of the organic halide (methylammonium iodide; MAI) and metal halide (lead iodide; PbI2) in a fixed solvent mixture of N,N-dimethylformamide (DMF):dimethylsulfoxide (DMSO). The surface morphology, optical characteristics, and crystallinity of the films produced with these four distinct solutions were investigated, and our analysis shows that the MAI:PbI2 (1.5:1.5) film is optimal under the current conditions. The PSCs fabricated from the (1.5:1.5) formulation were then integrated into the n-i-p solar cell architecture on fluorine-doped tin oxide (FTO) substrates, which exhibited a PCE of ~14.56%. Stability testing on this PSC device without encapsulation at 29 °C (ambient temperature) and 60% relative humidity (RH) under one-sun illumination while keeping the device at its maximum power point showed the device retained ~60% of initial PCE value after 10 h of continuous operation. Moreover, the recombination analysis between all four formulations showed that the bimolecular recombination and trap-assisted recombination appeared to be suppressed in the more optimal (1.5:1.5) PSC device when compared to the other formulations used in the n-i-p PSC architecture.

scholarly journals Role of Terminal Groups in Aromatic Molecules on the Growth of Al2O3-Based Hybrid Materials

2021 ◽  
Author(s):  
Arbresha Muriqi ◽  
Maarit Karppinen ◽  
Michael Nolan
Keyword(s):  
Hybrid Materials ◽  
Film Growth ◽  
Molecular Layer ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Hybrid Films ◽  
Molecular Layer Deposition ◽  
Aromatic Molecules ◽  
Inorganic Thin Films ◽  
Aromatic Components

Hybrid materials composed of organic and inorganic components offer the opportunity to develop interesting materials with well-controlled properties. Molecular Layer Deposition (MLD) is a suitable thin film deposition technique for the controlled growth of thin, conformal hybrid films. Despite the great interest in these materials, a detailed understanding of the atomistic mechanism of MLD film growth is still lacking. This paper presents a first principles investigation of the detailed mechanism of the growth of hybrid organic-inorganic thin films of aluminium oxide and aromatic molecules with different terminal groups deposited by MLD. We investigate the chemistry of the MLD process between the post-TMA pulse methyl-terminated Al2O3 surface and the homo- or hetero- bifunctional aromatic compounds with hydroxy (OH) and/or amino (NH2) terminal groups: hydroquinone (HQ), p-phenylenediamine (PD) and 4-aminophenol (AP). Double reactions of aromatic molecules with the alumina surface are also explored. We show that all aromatic precursor molecules bind favourably to the methyl terminated Al2O3, via formation of Al-O and Al-N bonds and CH4 elimination. While reaction energetics suggest a higher reactivity of the OH group with TMA in comparison to the NH2 group, which could enable the double reaction phenomenon for HQ we propose that the upright configuration will be present so that the organic molecules are self-assembled in an upright configuration, which leads to thicker hybrid films. Interactions between the methyl-terminated Al2O3 with substituted phenyls are investigated to examine the influence of phenyl functionalisation on the chemistry of the terminal groups. Reaction energetics show that phenyl functionalization actually promotes an upright configuration of the molecule, which leads to thicker and more flexible films, as well as tuning the properties of the aromatic components of the hybrid films. We also investigate the interactions between methyl-terminated Al2O3 with new possible MLD organic precursors, hydroquinone bis(2-hydroxyethyl)ether and 1,1'-biphenyl-4,4'-diamine. DFT shows that both aromatic molecules react favourably with TMA and are worthy of further experimental investigation.

scholarly journals Optical Parameters of As-Deposited and Annealed (Ga0.3In0.7)2Se3 Thin Films

2021 ◽  
Vol 66 (10) ◽  
pp. 885
Author(s):  
M. Pop ◽  
M. Kranjčec ◽  
I. Studenyak
Keyword(s):  
Refractive Index ◽  
Optical Absorption ◽  
Absorption Edge ◽  
Annealing Temperature ◽  
Wavelength Region ◽  
Inert Atmosphere ◽  
Optical Parameters ◽  
Short Wavelength Region ◽  
Spectral Ellipsometry ◽  
Evaporation Technique

The (Ga0.3In0.7)2Se3 films deposited by the thermal evaporation technique are annealed in the inert atmosphere (argon) for 1 h at temperatures of 50, 100, and 150 ∘C. The spectral ellipsometry is applied for measuring the spectral dependences of the refractive and extinction coefficients of as-deposited and annealed (Ga0.3In0.7)2Se3 films. The optical transmission spectra, as well as the optical absorption spectra of (Ga0.3In0.7)2Se3 films, are studied depending on the annealing temperature. The optical absorption edge for annealed (Ga0.3In0.7)2Se3 films is shifted to the short-wavelength region and broadens, as the annealing temperature increases. Parameters of the Urbach absorption edge are determined for as-deposited and annealed (Ga0.3In0.7)2Se3 films. The spectral dependences of the refractive index are analyzed in the framework of the Wemple–DiDomenico model. The nonlinear increase of the energy pseudogap, Urbach energy, and refractive index with the annealing temperature are revealed.

scholarly journals A review on Spray pyrolysis deposited CZTS thin films for solar cell applications

2021 ◽  
Vol 23 (09) ◽  
pp. 1196-1206
Author(s):  
C.S.A. Raj ◽  
◽  
S. Sebastian ◽  
Susai Rajendran ◽  
◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cell ◽  
Spray Pyrolysis ◽  
Low Cost ◽  
Thin Film Deposition ◽  
Research Area ◽  
Film Deposition ◽  
Deposition Technique ◽  
Czts Thin Films

Cu2ZnSnS4 generally abridged as CZTS is a potential material for economical thin film solar cells, due to its appropriate band gap energy of around 1.5 eV and great absorption coefficient of above 104 cm-1. All the constituents of this material are plentiful in the earth’s crust, and they are non-hazardous making it an elegant alternative. Subsequent to the early achievement of the CZTS based solar cell with its light to electrical conversion efficiency of 0.6%, significant advancement in this research area has been attained, particularly in the last seven years. Currently, the conversion effectiveness of the CZTS thin film solar cell has enhanced to 24%. More than 500 papers on CZTS have been available and the greater part of these converses the preparation of CZTS thin films by diverse methods. Until now, many physical and chemical methods have been engaged for preparing CZTS thin films. Amongst them, spray pyrolysis is a flexible deposition technique. Spray pyrolysis is a simple deposition technique that finds use in widespread areas of thin film deposition research. This method is appropriate for depositing good quality films with low cost, clean deposition, and simplicity and flexibility in the manufacturing design. This script, reviews the synthesis of CZTS semiconductor thin films deposited by spray pyrolysis. This analysis initiates with a portrayal of the spray pyrolysis system, and then establish the CZTS and preparation of the CZTS precursor for coating. A review of spray pyrolysis of CZTS thin films are discussed in detail. To conclude, we present perspectives for advancements in spray pyrolysis for a CZTS based solar cell absorber layer.

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