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The rapid technological developments enforce us to live in an increasingly electronic world, and the revolutionary usage of conjugated polymers in electronics in the late 1970s accelerated these developments, based on the unique characteristics of conjugated polymers, such as low cost, easy processing, mechanical flexibility, large-area application...
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Herein, a 3D composite electrode supported by g-C3N4 nanowire framework as scaffold and poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT: PSS) as conducting polymer is reported for flexible solid-state electrochemical capacitors. Compared to pure PEDOT: PSS, the composite electrodes have a greatly increased specific surface and sho...
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... P2 presents very weak bonds (C-N and C-O) at 1093 cm −1 and strong bonds (C≡C) at 2057, 2127 and 2157 cm −1 . Finally, P3 shows strong bonds (C≡C) at 2049, 2125, 2153 cm −1 and a broad bond (C-H) at 2815 cm −1[37][38][39][40][41][42]. EDS ...
Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), referred to as light-emitting polymer, was utilized in this study to synthesize thin films for polymer light-emitting applications (PLED). Three thin films named P1, P2 and P3 refer to three different ways of film fabrication. P1 consists of only PFO, P2 consists of brilliant blue FCF blend PFO, while P3 consists of PFO on polyaniline conductive layer; all these thin films were deposited onto ITO-coated glass substrates (20 Ω) using Doctor blade method. Toluene had been used as the solvent of PFO material. P1 exhibits the smoothest surface (6.43 nm), which is consistent with the FESEM result. The surface roughness increases dramatically in the case of P2 (63.00 nm) with the presence of valleys and high peak protuberance. The surface roughness continues to significantly increase (152.00 nm) with deeper valleys for P3. PL intensity of the thin films was found to be dependent on the structural properties, chemical composition and optical features of these films. Film absorption was shown to increase with surface roughness, resulting in increased PL intensity and replacement of chemical bonds. P3 exhibited the highest PL intensity at 439.7 nm, which is attributable to the relatively lower amount of oxygen in the film structure, increasing both surface roughness and absorption of the film, in addition to the substitution of chemical bonds. P2 displayed higher PL intensity than that of P1 as well. Thus, PFO blend and using a polyaniline conductive layer in the PFO film structure enhance the PL intensity, thereby improving the applicability of PFO films-based polymer light-emitting diodes (PLED).
... Through this, all atomic orbitals are saturated, which lead to insulator Fig. 15. The picture depicts the molecular structure and bond electronic structure of Polyethylene and Polyacetylene [141]. ...
... These π-bonds produce an unpaired electron per carbon through the chain, and each carbon connects to three other ones via a covalent bond. The p-orbital are overlapping and unhybridized P z orbitals, allow the delocalization of π electrons [137,138], which is the main reason of charge transport within molecular chains in conducting polymers [139][140][141]. Throughout the synthesis of the polymerization process in conducting polymers a substantial number of topological defects would appear. ...
In the past few years, there have been impressive breakthroughs to enhance the structure of organic solar cells (OSCs) in order to improve the performance. Resulting in increment of the power conversion efficiency (PCE) from 5% to 18% in OSCs and up to 25% in OSCs module. The Developments cause these thin and flexible, eco-friendly, and low-cost photovoltaic devices to be promising technology for wide range of applications such as internet of things (IOT), sensors, architecture, and wearable electronics.
Further, in this article, fundamental characteristics, operation principles, charge carriers transport mechanisms, and electrical model parameters of an OSC is reviewed. Considering polymers as main and most common building blocks of an OSC, charge transport and current models also have been studied. In addition, mobility characteristics, as one of the critical parameters affecting the OSC performance has investigated. Time of flight (TOF), space charge limited current (SCLC), charge extraction by linearly extracting voltage (CELIV), and impedance spectroscopy as the four fundamental methods to measure mobility in OSCs along with discussion about the advantages and drawbacks of each technique have been studied.
... where simple C-H stretching occurs between 3,000 to 2,800 cm −1 and the corresponding simple bending typically occurs between 1,500 to 1,300 cm −1 [39]. The different vibrational modes can be seen in Figure 6.3 [22]. There are slight energy differences between the vibrational modes in each category, for stretching, in plane bending, and out of plane bending. ...
... There are slight energy differences between the vibrational modes in each category, for stretching, in plane bending, and out of plane bending. Minor differences in the molecular structure can affect the Figure 6.3: Possible vibrational modes for molecules [22] location of peaks. In many instances functional groups are associated with a range of wavenumbers, which can be found in lookup charts. ...
Understanding the space environment and contamination concerns of a spacecraft is critical in designing a successful mission. The ability for a spacecraft to meet its science objectives relies on systems functioning as intended. A concern for maintain- ing performance while on orbit is molecular contamination. Silicones have previously been shown to form a silica layer on their surfaces when exposed to atomic oxygen. For silicone contamination, this translates to a silica film on the contaminated surface. Missions such as Long Duration Exposure Facility and Evaluation of Oxygen Interactions with Materials III have indicated that the silica film can trap deposits of carbon contamination to the surface during its formation. This phenomenon was explored in this research using RTV-S 691 silicone and Braycote 601EF for the carbon-based contaminant. The experiment involved contaminating an aluminum substrate in three different configurations; one for each contaminant individually on the substrate, and one with both contaminants. These samples were exposed to atomic oxygen for a period of 24 hours, then analyzed with Fourier transform infrared spectroscopy. The trends in infrared spectra for the different test cases were characterized for comparison. The trend for samples with a carbon-to-silicone contamination ratio of greater than ten to one showed peaks corresponding to those seen on the singularly contaminated samples. When the concentration of silicone was increased, the trend in spectral results showed peaks corresponding to Braycote before atomic oxygen exposure. At certain concentrations of RTV silicone to Braycote, the trends suggest Braycote is partially protected from atomic oxygen by a silica film. This indicates that silicone conversion to silica in atomic oxygen can trap contaminants to a surface.
... The π state represents the highest occupied molecular orbital (HOMO) and π* state represents the lowest unoccupied molecular orbital (LUMO) which corresponds to the valance band level and conduction band level in the inorganic semiconductors, respectively. The energy difference between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) represents energy bandgap E g [23,24]. ...
... The hybridization orbitals for types sp 1 , sp 2 or sp 3[24]. ...
In this work, the preparation and study of perovskites compounds is through
using chemical methods for methylammonium halides MABr, MAI, and
MACl and lead halides PbBr2, PbI2, and PbCl2.
The main objective of the study is to successfully prepare new types of
perovskite using the one-step method by changing both the type of lead
halides or the weight ratio, as well as changing the type of methylammonium
halides with a fixed weight ratio in methylammonium bromide, where the films
were classified P1, P4, P7 were prepared in weight ratios (0.22:0.59,039,079)g
of MABr/PbI2, and films P2, P5, P8 were prepared in weight ratios
(0.22:0.59,039,079)g of MABr/PbBr2 and films P3, P6, P9 were prepared by
weight (0.22:0.59,039,079)g of MABr/PbCl2, and films P10, P11 were prepared
by weight (0.52:052)g of MABr/MAI and MACl, and the effect of this change
was studied.
... More importantly, shift of FTIR peaks within FTIR spectrum of PANi-F-S, especially for peaks around 1112 and 1158 cm −1 , shows higher degree of protonation in PANi-F-S than pristine PANi. Other peaks between ranges 1900-1903 cm −1 and 2091-2093 cm −1 are attributed to the C=C double bond carbon atoms [65] and azide functional groups (i.e., N − ≡ N + = N − ) [66], respectively. Large shoulder in the FTIR spectrum of PANi-F-S of about 3212 cm −1 corresponds to hydroxyl functional groups (i.e., -OH) [67]. ...
Mercury as the 3rd most toxic, non-biodegradable, and carcinogenic pollutant can adversely affect the ecosystem and health
of living species through its bioaccumulation within the nature that can affect the top consumer in the food chain; therefore,
it is vital to sense/remove Hg2+ within/from aqueous media using practical approaches. To address this matter, we modified
the glassy carbon electrode (GCE) with ultra-sensitive, interconnected, sulfurized, and porous nanostructure consisted of
polyaniline-Fe3O4-silver diethyldithiocarbamate (PANi-F-S) to enhance the sensitivity, selectivity, and limit of detection
(LOD) of the sensor. Obtained results showed that at optimum conditions (i.e., pH value of 7, deposition potential of −
0.8 V, and accumulation time of 120 s), for Hg2+ concentration ranging from 0.4 to 60 nM, the modified electrode showing
linear relative coefficient of 0.9983, LOD of 0.051 nM, LOQ of 0.14 nM, and sensitivity of 1618.86 μA μM−1 cm−2
highlights superior sensitivity of the developed platform until picomolar level. Additionally, the modified electrode showed
ideal repeatability, stability, reproducibility, and selectivity (by considering Zn2+, Cd2+ Pb2+, Cu2+, Ni2+, and Co2+ as metal
interferences) and recovered more than 99% of the Hg2+ ions within non-biological (mineral, tap, and industrial waters) and
biological (blood plasma sample) fluids.
... Absorption band of different chemical bonds, readapted from[73].To evaluate the absorption of the evanescent component of the guided mode, 1.8 µmthick S1818 photoresist has been spin coated on the spiral waveguides based on platform A.A schematic waveguide cross-section and the SEM image are presented in Fig.2.4.3. The SEM image of waveguide confirms that the waveguide is fully covered by the photoresist. ...
Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances, as most of the molecules have their vibrational and rotational resonances in the mid-IR wavelength range. Commercially available mid-IR systems are based on bulky and expensive equipment, while lots of efforts are now devoted to the reduction of their size down to chip-scale dimensions. The use of silicon photonics for the demonstration of mid-IR photonic circuits will benefit from reliable and high-volume fabrication to offer high performance, low cost, compact, lightweight and power consumption photonic circuits, which is particularly interesting for mid-IR spectroscopic sensing systems that need to be portable and low cost. Among the different materials available in silicon photonics, Germanium (Ge) and Silicon-Germanium (SiGe) alloys with a high Ge concentration are particularly interesting because of the wide transparency window of Ge up to 15 µm. In this context, the objective of this thesis is to investigate a new Ge-rich graded SiGe platform for mid-IR photonic circuits. Such new plateform was expected to benefit from a wide transparency wavelength range and a high versatility in terms of optical engineering (effective index, dispersion, …). During this thesis, different waveguides platforms based on different graded profiles have been investigated. First it has been shown that waveguides with low optical losses of less than 3 dB/cm can be obtained in a wide wavelength range, from 5.5 to 8.5 µm. A proof of concept of sensing based on the absorption of the evanescent component of the optical mode has then been demonstrated. Finally, elementary building blocs have been investigated. The first Bragg mirror-based Fabry Perot cavities and racetrack resonators have been demonstrated around 8 µm wavelength. A broadband dual-polarization MIR integrated spatial heterodyne Fourier-Transform spectrometer has also been obtained. All these results rely on material and device design, clean-room fabrication and experimental characterization. This work was done in the Framework of EU project INsPIRE in collaboration with Pr. Giovanni Isella from Politecnico Di Milano.
... In 1977, Shirakawa, MacDiarmid and Heeger discovered that the conductivity of conjugated polymers can be multiplied about 5 times of magnitude for some types of semiconductor [14]. Organic semiconductors actually have two types of materials that are mainly composed of carbon C and hydrogen H atoms, and classified into two types of organic semiconductors, molecular organic semiconductors and polymeric organic semiconductors [14,15] The hybridization orbitals for types sp 1 , sp 2 or sp 3 [18]. ...
... The π state represent the highest occupied molecular orbital (HOMO) and π* state represent lowest unoccupied molecular orbital (LUMO) which correspond to the valance band level and conduction band level in the inorganic semiconductors , respectively. The energy difference between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) represent energy bandgap E g , Figure1.9 show the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and energy bandgap E g [13,14,17,18]. Where is density of molecular here, E G is the position of the maximum distribution and is the standard deviation conductivity ...
... The data shows an absorbance edge at 530 nm and energy bandgap of 2.33 eV. These results are consistent with Bansode and Ogale[77].18 The absorbance spectrum of PS2 (MAPbICl 2 )film. ...
The main objective of this work was to study the organic-inorganic perovskite to fabricate a solar cell. As well as to explore the benefit of the perovskites band gap tuning to design a photodetector that can be operated either in a specific or wide range of the wavelengths.
Different types of perovskites have been prepared successfully and classified into PS1, PS2, PS3, PS4, PS5, PS6, PS7, PS8, PS9, PS10, and PS11 using the one-step method. These perovskite types range from nanometric to micrometric dimensions with different energy gaps. The halide types and its concentration have been changed both in methylamine slat (MA) or lead (Pb) to prepare a new type of perovskites and study the effect of the change. It has been displaced in the energy gaps and in the absorbance edges of some perovskites due to change in the type and concentration of halides.
The perovskite photonic device consisted of FTO glasses substrate which was used as a light window and electrode. Electron transport materials (ETM) which allow one or more electrons to pass to the cathode and same time prevent holes from passing through it. TiO2 nanorod was one of the electron transport materials (ETM) which were prepared via hydrothermal method under 160oC for about 7hs. The advantage of prepared TiO2 as nanorod was to increase the area of the surface. Finally, the perovskite can represent the active layer, and metal represents the electrode.
Three types of perovskites which were prepared previously, namely PS3, PS4, and PS7 were chosen to fabricate perovskite solar cells. The parameters of the solar cell were calculated depending on current-voltage I-V characteristic curve under simulated solar light (100 mW.cm-2). The efficiency was recorded 1.23 % for the PS3 sample when open circuit voltage VOC=0.43 V, short circuit current JSC=10.7 mA.cm-2, and the fill factor FF=0.26. However, the other efficiencies reached up to 0.9% for the PS4 and 0.1% for PS1 samples.
The other application of perovskite devices in this study was in the photodetectors. The main goal of the photodetector work was its responsiveness to the wavelength of the light. This responsiveness is dependent on the bandgap of a photodetector. This was carried out by tuning the bandgap of photodetectors and that was conducted by controlling the type or concentration ratio of the halide which can easily be fabricated with low cost.
The photodetectors include four types namely, PS1, PS3, PS4, and PS7. Three wavelengths were used to illumine the photodetectors at 400nm (has intensity = 0.2 mW.cm-2) , 460nm, and 640 nm ( have intensity = 0.9 mW.cm-2) depending on the bandgap of perovskites. The bias voltages Vbias for photodetectors were varied between 0 V as a photovoltaic photodetector and 0.5, 1, and 1.5 V.
The fabricated photodetectors operate in the forward and reverse bias at the same time. The results of photoresponse and photodetectors parameters for the forward and reverse bias were almost equal.
The photoresponse was directly proportional to the bias voltages and the intensity of illumination. The quantum efficiency QE= 411% for Vbias=0V and increased to 1597%, 1845% when Vbias increased to 0.5, 1 V, respectively, and reached to 2303% at Vbias =1.5 V. These values represented the best photodetector findings which recorded for the PS3 at 400nm wavelength. Rise and fall time was constant with the variable frequency of illumination.
