Decrease In Optical Transmittance Research Articles

Investigation of structural, optical, electrical, thermoelectric and optoelectronic properties of undoped ZnO, Sb-doped ZnO and Sb–B co-doped ZnO thin films

Pure ZnO (Zinc oxide), 1 % Sb (antimony) doped ZnO (Zn0.99Sb0.01O), and 1 % Sb–1% B (boron) co-doped ZnO (Zn0.98Sb0.01B0.01O) solutions were prepared using the sol-gel method. These solutions were deposited as thin films on glass and Si (silicon) substrates via dip coating and spraying methods. In this study, doping ZnO with low amounts of Sb and B provided the conversion of the n-type semiconductor ZnO into a p-type semiconductor. The produced thin films were pure and had wurtzite ZnO polycrystalline structure. The nanodot morphology of ZnO turned into a mixture of nanodot and nanorod structures with only Sb doping. Moreover, the band gap energy of ZnO decreased from 3.26 eV to 3.24 eV with Sb doping and to 3.23 eV with Sb and B co-doping, accompanied by a decrease in optical transmittance depending on film thickness. All samples exhibited diode characteristics. According to the created Au/ZnO–Zn0.99Sb0.01O – Zn0.98Sb0.01B0.01O/Si diodes, it was understood that the ideality factor, barrier height, and serial resistance of ZnO material decreased with doping. Especially, the ideality factor, barrier height, and serial resistance of the ZnO sample decreased from 4.95, 6.80 eV, and 1.42 × 105Ω to 4.35, 6.25 eV, and 2.60 × 103Ω, respectively, with Sb and B co-doping. The photovoltaic performance of 1 % Sb-doped thin film increased 100 times compared to pure ZnO, reaching the efficiency from 0.006 to 0.600. However, the most suitable material for use as a photodiode was found to be the 1 % Sb–1% B co-doped sample. While the leakage current of this sample is around −8.0 × 10−5 A at −3 V under 100 mW/cm2 light, it is 9.5 × 10−8 A at −3 V in the dark. Furthermore, the 1 % Sb-doped thin film exhibited the best performance as a thermoelectric material at 600 K, achieving a figure of merit (ZT) of 0.00052. Overall, co-doping with Sb and B enhanced the optical, electrical, and structural (more homogeneous and less surface roughness) properties of ZnO, while improving its optoelectronic functionality such as photodiode. On the other hand, thermoelectric and solar cell properties of ZnO were enhanced with only 1 % Sb doping. A hybrid energy system containing thermoelectric and solar cells was produced cheaply and simply for wide application areas with this study. Moreover, with such a low doping amount, p-type material production was achieved, and important physical properties of the ZnO material were improved.

Enhancing charge transport and photoluminescence characteristics via transition metals doping in ITO thin films

Abstract This study presents the synthesis and characterization of pristine and transition metal (Co, Fe, and Zr)-doped indium tin oxide (ITO) thin films fabricated via RF magnetron sputtering. The effect of transition metal doping on ITO thin films properties was comprehensively examined using numerous spectroscopic and microscopic methods such as XRD, FTIR, and SEM coupled with EDX, UV–visible and PL spectroscopy, and four-probe and J–V measurements. The cubic crystal structure of the materials was confirmed through XRD spectroscopy, while FTIR results validated the existence of chemical bonds, signified by sharp peaks at 608 cm−1 and 667 cm−1 in the fingerprint region. SEM imaging revealed a granular-like agglomerated structure, with EDX confirming the elemental composition of the samples. The incorporation of Co, Fe, and Zr ions into ITO is aimed at improving photoconductivity and the optical bandgap, with the ultimate objective of enhancing performance in photovoltaic applications. Our findings showed a significant decrease in optical transmission in the visible spectrum. The bandgap also experienced a minor decrease from 3.67 eV to 3.53 eV. Analysis of the photoluminescence spectra exhibited the majority of emission peaks in the UV region, ascribed to electronic transitions occurring via band-to-band and band-to-impurity interactions within the ITO. Electrical measurements indicated lower resistance, higher current flow, and increased carrier concentration in transition metals–doped ITO compared to the undoped ITO, with Zr-doped ITO exhibiting the highest conductivity and optimal charge flow among all dopants. These promising findings in terms of optical, structural, and electrical attributes signal the potential of these materials for photovoltaic system applications.

Research on Flexible Transparent Conductive Electrodes Based on Ultra-Thin Ag in the Form of Grain Boundary with IZO Layer

In this paper, we investigated a transparent conductive electrode (TCE) that satisfies electrical, optical, and mechanical properties, formed by depositing ultra-thin Ag metal in the form of a random grain boundary with an indium zinc oxide (IZO) layer on a PET substrate. Commonly used ITO electrodes are brittle and difficult to apply to flexible devices. In contrast, IZO-based electrodes are mechanically flexible and can be used as flexible TCE, and have high electrical and optical properties. A 90 nm thick IZO electrode has a transmittance of 90.2% at a wavelength of 460 nm and a sheet resistance of 29.5 ohm/sq. In particular, Ag metal was deposited in the form of an atypical metal island using an RF magnetron sputtering system. At 3 nm there were few metal clusters in the form of islands, and many void channels were formed, resulting in high sheet resistance as well as a decrease in optical transmittance. However, about 5 nm thickness, the number of void channels decreased and the optical path changed, improving the electrical and optical properties. Results showed that the sheet resistance was reduced to 19.8 ohm/sq, and the transmittance was also increased to 91.1%. The mechanical properties were also found to be the same for conventional IZO and Ag/IZO TCE.

Hyperspectral analysis of amyloid beta (Aβ) evolutional changes in preclinical to late‐stage Alzheimer’s disease using matched brain and retinal tissue

AbstractBackgroundAlzheimer’s disease (AD) is a progressive, degenerative brain disorder that leads to cognitive impairment and eventually death. It is marked by buildup of abnormal amyloid aggregates (Aβ) in the brain. This study aimed to elucidate the neuropathologic sequence and corresponding [RetiSpec] hyperspectral signals of Aβ evolutional changes in preclinical to late‐stage AD using retinal and brain samples.MethodWe used brain‐ and retina‐matched human tissue samples from the NIH Brain Bank at Johns Hopkins. Study groups included: No AD neuropathologic change with negative AD neuropathology (n = 15); Low‐level AD neuropathologic change with positive AD neuropathology (n = 15); High level AD neuropathologic change with positive AD neuropathology (n = 15). To validate retinal hyperspectral imaging (rHSI) detection of Aβ in these retinal samples, we quantified Aβ oligomers (AβOs) in human retinal tissue. Immunohistochemistry was performed. We used humanized, affinity‐matured, IgG2 mAβ selective biotinylated antibody (ACU‐193) to detect soluble AβOs in retinal and brain tissues followed by objective quantification of ACU193 retinal staining by performing annotations and data extraction using QuPath software. One‐way ANOVA and t‐tests were performed to compare between controls and AD stages.ResultWhen assessing ACU193 staining present from retinal tissue samples, we observed 29‐53% retinal tissue area positivity in controls and 15‐72% retinal tissue area positivity in the AD group. Level of AD pathology demonstrated an effect on the rHSI spectra (450‐600nm) in regions near the optic disc and the ventral periphery: intermediate AD pathology showed the strongest rHSI signature (decrease in optical transmittance) followed by high, then low AD pathology samples. Correlation of the Braak neurofibrillary tangle stage and ΔOD offered a Pearson r score of 0.79 (p = 0.004).ConclusionThis study was the first to assess and quantify AβOs in clinically, neuropathologically, and hyperspectrally characterized postmortem matched brain and retinal tissues. Progression of well‐established neuropathologically classified AD stages (e.g Braak) may correlate with retinal AβO levels measured using rHSI. Certain retina regions that share nervous tissue with the brain (optic disc, periphery) are likely more sensitive to rHSI‐mediated detection of AD pathology. Larger samples are needed to comprehensively assess and quantify retinal AβOs.

Optical and Surface Structure Modification of Gallium Arsenide

The surface morphology modification and optical property modification of semi-insulating gallium arsenide sample implanted with 100 keV silicon ions with the fluences ranging between 5 × 10[Formula: see text] and 4 × 10[Formula: see text] ion cm[Formula: see text] were analyzed using scanning electron microscopy and UV–Vis–NIR spectroscopy study. Scanning electron microscopy study revealed pore-like structure formation on the surface of gallium arsenide samples after silicon ion implantation. The size of these pore-like structures was found to increase with increasing ion fluence. Energy dispersive X-ray analysis showed an increase in silicon concentration in the gallium arsenide sample after silicon ion implantation with increasing ion fluence. The UV–Vis–NIR spectroscopy study revealed a decrease in optical transmission for silicon ion implanted gallium arsenide sample with increasing ion fluence. An additional absorption band was observed for the gallium arsenide sample implanted with the highest fluence (4 × 10[Formula: see text] ion cm[Formula: see text]. Urbach tail energy was found to increase with respect to ion fluence.

Photocurrent performance and enhancement of opto-electronic properties of spray pyrolysis deposited ZnO thin films via V-doping

This study reports on the deposition of highly transparent conducting n-type zinc oxide (ZnO) thin films on FTO substrates, via an optimized doping process. Our work is focused on doping zinc oxide with vanadium (V) using spray pyrolysis technique and ensure the synthesis of nanoparticles-shaped ZnO, with an improved optical, microstructural and electrical properties for solar cells applications, as optical window material. Undoped and V-doped ZnO thin films, with careful optimized amounts (2, 4, 6 and 8 at.%), were grown at maintained 550∘C pre-heated substrate during the deposition process, which enables us to obtain nano-sized ZnO particles. We proved that 4 at.% is the optimum V content that enhances the crystallinity of the grown thin film noticeably. With an average transmittance of 80%, the deposited thin films revealed high transparency in the visible domain with a slight decrease in optical transmission which might result from additional scattering. UV-Visible analysis showed that increasing V amounts, a resulting decrease in the energy bandgap ([Formula: see text]) is obtained from 3.26[Formula: see text]eV to 3.17[Formula: see text]eV for 4 at.% of V content. Moreover, deep level defects in zinc oxide can be reduced with vanadium doping and consequently strengthen the UV emission. The UV emission peak intensity rises with increasing V-doping amount then decreases slightly at 8% of V content. The electrical properties measurements showed a decrease in resistivity from 2.8 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm to 0.9 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm when doping with 4 at.% of V. The crucial effect of the V-doping of ZnO was also demonstrated via the enhancement of carrier mobility that attains 38.5[Formula: see text]cm2/V[Formula: see text]⋅[Formula: see text]s at the optimum vanadium content. The photocurrent analysis revealed much higher visible light absorption in the V-doped zinc oxide thin films than that of undoped film. The photocatalytic activity enhancements are attributed to the lower recombination rate of the photogenerated electron-hole pairs, the narrowed bandgap, yielding a higher photocatalytic performance.

Ladder Polyphenylsilsesquioxanes and Their Niobium-Siloxane Composite as Coating Materials: Spectroscopy and Atomic Oxygen Resistance Study.

In order to expand the range of materials that can be used in outer space and in development of small spacecraft, ladder polyphenylsilsesquioxanes with different molar weights and the Nb-siloxane composites based on them were studied. The properties of the polymer films were studied, including tests in an oxygen plasma flow. Both initial and filled ladder polymers feature extremely low erosion coefficients in the region of 10-26 cm3/atom O at a high fluence of atomic oxygen of 1.0 × 1021 atom O/cm2. Ladder polyphenylsilsesquioxane films irradiated with atomic oxygen (AO) retain their integrity, do not crack, and exhibit good optical properties, in particular, a high transmittance. The latter slightly decreases during AO exposure. The Nb-siloxane filling retains the AO resistance and slight decrease in optical transmission due to diffuse scattering on the formed Nb-[(SiO)x] nanoparticles. Ladder polyphenylsilsesquioxanes demonstrate their suitability for creating protective, optically transparent coatings for small spacecraft that are resistant to the erosive effects of incoming oxygen plasma.

Effect of precursor concentration on stoichiometry and optical properties of spray pyrolyzed nanostructured NiO thin films

In this study, spray pyrolysis was used to produce nanostructured NiO thin films from high purity nickel acetate (Ni(CH3COO)2.3H2O) precursors on pre-heated ultrasonically cleaned soda-lime glass substrates. The metallic constituent concentrations in the films were varied, and the precursors were produced in distilled water at various molarities ranging from 0.1 to 0.4 M. In the study, the field-emission scanning electron microscope (FESEM) results strongly confirmed adherence of the films to the glass substrate at 350 °C. The presence of Ni and O in the samples was confirmed using Rutherford backscattering spectroscopy (RBS), X-ray diffractometry (XRD) and energy dispersive X-ray spectroscopy (EDX). For the 0.1 M NiO thin films, the thickness was approximately 43 nm, and for the 0.2 M, 0.3 M, and 0.4 M films, the thickness was 46 nm, 47 nm, and 49 nm, respectively. The XRD findings were supported by the increased Raman intensity peaks with increased precursor concentration, which confirmed the films' improved crystallinity. For the same number of passes of films deposition, as the molar concentration increases, the films thickness increases. The amount of nickel in NiO thin films increases as the molarity increases, but the amount of oxygen in NiO thin films decreases as the molarity increases. It was discovered that as molarity increases, the optical transmittance decreases and the optical band gap narrows. The qualities of NiO discovered in this study suggest the films’ potentials for usage as window layer and buffer material in thin film solar cells.

Improvement in optical absorption and emission characteristics of polymethyl methacrylate in solution cast polymethyl methacrylate/polyvinyl carbazole polyblends

Polymer blends have got considerable attention for their potential optoelectronic and photonic applications due to several advantages such as easy processing, low cost, flexibility, and good mechanical properties. This work reports the structure and optical properties of solution cast binary blends of poly (methyl methacrylate) (PMMA) and poly (vinyl carbazole) (PVK). Here, the position and/or intensity of characteristic FTIR peaks reveal the changes of the structure of PMMA on PVK content while the surface morphology changes from highly smooth for pure PMMA to flaky structured (PVK 5%) and then to agglomerated morphologies for these blends. A red shift in optical absorption edge and decrease in optical transmission with PVK content in PMMA based blends. The emission spectra exhibit intensity escalation by 340 times with respect to PMMA for PVK-15 blends and then decreases with further addition of PVK in these blends. These results are very important for the advent of new optoelectronic functionalities for these polymer blends.

Induced phase transition in monocrystalline solids solutions PbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--29PbTiO-=SUB=-3-=/SUB=- and PbZn-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--9PbTiO-=SUB=-3-=/SUB=-: similarity and difference

The kinetics of the induced phase transition in single-crystal relaxor solid solutions PbMg1/3Nb2/3O3-29PbTiO3 and PbZn1/3Nb2/3O3-9PbTiO3 is studied when an electric field is applied along the [001] direction. At temperatures below the temperature of the morphotropic phase transition, the changes in the dielectric constant and optical transmission in electric fields are studied. It is shown that the decrease in optical transmission with time is associated only with a change in the sizes of nanoregions during the phase transition. It was found that the induced phase transition proceeds differently in these crystals. In PMN-29PT crystals, the formation of ferroelectric phases and the rapid establishment of macroscopic polarization are preceded by a certain delay time, while in PZN-9PT crystals, the ferroelectric phase is induced immediately after the application of the field without a delay time. The results obtained are explained by the different structures of the low-temperature phases in these compounds. Keywords: ferroelectricity, relaxors, induced phase transition.

Activation ability of Gd dopant in the ZnSe single crystals

Rare-earth elements are widely used as doping materials as they considerably change the semiconductor optical, electrical, magnetic and radiative properties. This work explores the influence of Gadolinium (Gd) as a dopant on the radiative, optical and magnetic properties of the Zinc Selenide (ZnSe). ZnSe single crystals were grown by the physical transport method and doped during the growth process using a GdSe source. A wide range of characterization equipment was employed to analyze the obtained ZnSe:Gd single crystals. Intracenter radiative transition of the Gd has not been detected. Gd ions activate the background impurities, causing radiative transitions from the conduction band to the Cu2+ level and intracenter transitions within V3+, V2+ and Cr2+ ions. At the same time, the edge band intensity is dependent on the dopant concentration. Optical transmittance decreases, but the position of the fundamental absorption band is unchanged. Single crystals have a zinc blende crystal structure, and Gd ions do not form complexes with native defects or background impurities.

Photostable transparent wood composite functionalized with an UV-absorber

Transparent wood composite (TWC) is an emerging material which combines good optical and mechanical properties with potential applications in smart windows, energy efficient building elements and solar energy concentrators etc. UV resistance of TWC is important for its suitability to be used in outdoor applications as a building material. In this study, functional TWC was prepared by lignin modification bleaching of poplar wood veneers followed by infiltration with epoxy resin doped with an UV absorber (2-(2H-Benzotriazol-2-yl)-4, 6-di-tert-pentylphenol) (conc. 1.0 and 1.75% w/v). Highly stable TWC (thickness 2 mm) with high optical transmittance was fabricated. The photostability of TWC was evaluated by exposing TWC sheets to a UVA340 fluorescent lamp in an accelerated weathering tester. For a comparison, wood, bleached wood, and epoxy samples were also subjected to UV light irradiation and the extent of degradation was evaluated by measuring colour change (yellowness index measured using spectrocolorimeter), chemical changes (monitored using FTIR spectroscopy) and optical transmittance. TWC was highly sensitive to UV light exposure and exhibited rapid photo-discolouration, chemical degradation and a decrease in optical transmittance. Incorporation of UV absorber in epoxy resin considerably reduced discolouration and photo-degradation of TWC. Moisture absorption behaviour (water uptake) of TWC was also evaluated by immersing it in water. The results indicated that TWC undergoes significant photo-degradation and needs application of UV stabilizer for its outdoor applications.

Индуцированный фазовый переход в монокристаллических твердых растворах PbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--29PbTiO-=SUB=-3-=/SUB=- и PbZn-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--9PbTiO-=SUB=-3-=/SUB=-: сходство и различие

The kinetics of the induced phase transition in single-crystal relaxor solid solutions PbMg1 / 3Nb2 / 3O3-29PbTiO3 and PbZn1 / 3Nb2 / 3O3-9PbTiO3 is studied when an electric field is applied along the [001] direction. At temperatures below the temperature of the morphotropic phase transition, the changes in the dielectric constant and optical transmission in electric fields are studied. It is shown that the decrease in optical transmission with time is associated only with a change in the sizes of nanoregions during the phase transition. It was found that the induced phase transition proceeds differently in these crystals. In PMN-29PT crystals, the formation of ferroelectric phases and the rapid establishment of macroscopic polarization are preceded by a certain delay time, while in PZN-9PT crystals, the ferroelectric phase is induced immediately after the application of the field without a delay time. The results obtained are explained by the different structures of the low-temperature phases in these compounds. Key words: ferroelectricity, relaxors, induced phase transition.

Enhanced electrical conductivity of PEDOT-encapsulated silver nanowire film pretreated with surfactants

Flexible, transparent and conductive films (TCFs) were prepared with silver nanowires (AgNWs) and the conductivity was enhanced via tuning junction resistance between nanowires treated by different surfactants and encapsulated by poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). The results showed that the conductivity of AgNW TCFs was obviously enhanced after being immersed into surfactant solutions because the AgNWs would approach each other directly after dislocating away from polyvinyl pyrrolidone (PVP) and the junction resistance sharply decreased. Moreover, the transmittance of AgNW TCFs immersed into different surfactant solutions just decreased little because the halogen ions induced the formation of silver nanoparticles on the surface of AgNWs. Besides, the conductivity of AgNW TCFs encapsulated by PEDOT:PSS was also enhanced because the charges can transfer between PEDOT chains and AgNWs with the little decrease of optical transmittance. Graphical abstract

ITO/Au/ITO multilayer thin films on transparent polycarbonate with enhanced EMI shielding properties

ITO/Au/ITO multilayer thin films were deposited onto polycarbonate substrate via magnetron sputtering technique without intentional heating. The deposition times of both ITO and Au layers were studied to optimize the overall transparency and conductivity. As-prepared thin films were characterized using X-ray diffraction analysis, secondary ion mass spectroscopy, scanning and transmission electron microscopy, atomic force microscopy and physical property measurement system. The optical measurement results revealed that the transmittance of the films were enhanced by increasing the gold deposition time up to 15 s. Beyond this point, further increasing the duration caused a decrease in optical transmittance. Upon optimization of the Au deposition time, the deposition duration of ITO layers was also studied to increase electromagnetic interference (EMI) shielding effectiveness (SE). Maximum EMI SE in this work was measured as 26.8 dB, yielding 99.8% power attenuation, which was verified by simulation results.

Structural and Optical Properties of Gamma Irradiated CuGaO2 Thin Film deposited by Radio Frequency (RF) Sputtering

In space, semiconductor devices are vulnerable to various effect of high energy level of radiation causing single event upsets (SEU), damaging or altering the lattice structure. In this work, p-CuGaO2was selected due to its relatively wide bandgap and a visibility transmittance up to 80% as a potential semiconductor material capable of withstanding harsh radiation environment. p-CuGaO2thin films were deposited by RF powered sputtering on indium tin Oxide (ITO) substrates at 250°C deposition temperature and annealed at 300 °C. Structural morphology and optical properties of CuGaO2 thin film were investigated before and after irradiation. The samples were irradiated using Cobalt-60, gamma-ray with a dose ranging from 10 kGy-200 kGy. The structural properties reveal that the CuGaO2 films shows a diffraction peak at 20=38.051° (012) before irradiation. The optical properties of deposited CuGaO2 thin film, exhibits approximately 75% optical transmittance in the invisible region at pre-irradiation and post-irradiation results shows a decrease of optical transmittance of 55%. At a dose of 200 kGy, the band gap of CuGaO2 is 3.62 eV which indicates that it is still within the acceptable range of a semiconductor properties. Early results of CuGaO2 shows good mitigation towards irradiation thus indicating that CuGaO2 thin film is capable of withstanding harsh radiation environment while retaining its semiconductor properties.

Wrinkled titanium nitride nanocomposite for robust bendable electrodes

Electrical contacts and interconnections are critical components for all electronic devices. Bendable electrodes with enhanced electro-mechanical properties are highly desirable to develop innovative wearable electronic devices. Herein we report on a fabrication method for robust bendable coatings based on titanium nitride (TiN) thin films and silver nanowires (Ag NWs). TiN and TiN-AgNWs nanocomposites were deposited on polyethylene terephthalate (PET) substrates using a plasma enhanced pulsed laser deposition (PLD) technique. The resulting TiN coatings exhibit excellent adhesion to PET and their sheet resistance can be tuned using a dual frequency PLD process and further decreased by incorporating Ag NWs into the TiN layers. Sample sheet resistance was decreased down to values as low as corresponding to the formation of TiN-AgNWs nanocomposites. The electro-mechanical robustness of TiN based coatings were evaluated by four-probe resistance measurements in situ under cyclic bending tests. We show that the TiNAgNWs nanocomposites surpass both ITO and Ag NWs coatings in terms of mechanical robustness and electrical conductivity respectively. These nanocomposites withstand high strain fatigue loading up to ϵ = 2.6%, keeping RS below 5 Ω/□. The data demonstrates that the incorporation of Ag NWs in TiN coatings improve the mechanical robustness, limiting the crack growth and propagation, with low optical transmittance decrease (≈11%). These results indicate that Ag NWs based nanocomposites are attractive materials for flexible electronic devices.

Investigation on the impact of xylenol orange dye on the growth and properties of unidirectional grown KDP crystals for photonic applications

Unidirectional (1 0 1) bulk size xylenol orange dye-doped potassium dihydrogen phosphate single crystals were grown by Vacuum Assisted Sankaranarayanan-Ramasamy method so as to improve the properties of the crystal. The objective is to study the impact of organic dyes on properties of the crystal and understand how it could be used for relevant applications. Optical transmission decreases and thermal properties remain the same for the dye-doped crystals whereas the addition of dye improves mechanical, dielectric and photoconduction properties. On comparison, a stronger absorption is identified at 480 nm for the dye-doped crystal. Laser damage threshold confirms that 0.01 M dye-doped crystal has the value 12.40 GW/cm2 as compared to 8.59 GW/cm2 for pure crystal, whilst, second harmonic efficiency as observed by Kurtz test decreases on increasing dye concentration such that crystals of pure, 0.001 M and 0.01 M dye-doped have the respective values of 26.4 mV, 18.1 mV and 17.6 mV.

Enhancing the photovoltaic characteristics of organic solar cells by introducing highly conductive graphene as a conductive platform for a PEDOT:PSS anode interfacial layer

We propose a remarkably conductive polymer composite that results from highly conductive pristine graphene (PG) being doped with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). With the addition of PG to a PEDOT:PSS (B-PE) dispersion acting as a conductive platform, the sheet resistance can be lowered from 368.54 Ω/sq to 114.67 Ω/sq for the graphene-PEDOT:PSS (G-PE) over a bare glass substrate. Importantly, this only causes a minor decrease in optical transmittance of approximately 4.16% at 550 nm, and generates a noticeable decrease in the surface roughness profile of ~ 11.42 nm. XRD, Raman spectroscopy, and XPS analyses were used to verify that various types of chemical bonds are formed between the PG sheets and B-PE molecules. Due to these chemical interactions, a huge number of electrons are transferred from the PG sheets to the PEDOT, creating a net positive charge among the carbon atoms in the PG sheets. This results in an increase in the conductivity of the G-PE composite and, consequently, improves the power-conversion efficiency (PCE; 4.52%) of organic solar cells utilizing G-PE composite hole transport layers (HTLs). This enhancement in the PCE of G-PE HTL-based devices is compared with devices fabricated from either B-PE or PG HTLs alone, these devices achieved a PCE of only 4.18% and 3.87%, respectively.

Aerosol assisted chemical vapor deposition (AACVD) synthesis of nanostructured cauliflower patterning in MWCNT doped tungsten oxide

We report nanostructured tungsten oxide (WO) cauliflowers for the first time that are fabricated onto silica glass substrate at 400 °C by aerosol assisted chemical vapor deposition using tungsten hexacarbonyl and multiwalled CNTs in toluene. The deposited films are characterized by Scanning electron microscopy, Energy dispersive x-ray spectroscopy, X-ray diffractometry, Fourier transform infrared and UV–VIS spectroscopy and four-point probe for microstructural, optical and electrical properties. Surface morphology exhibits the growth of nanocauliflowers followed by the aggregation of spherical nanoparticles with high angle grain boundaries. Structural information reveals the transformation of triclinic to tetragonal phase with preferential switching from (0 2 0) to (0 0 1) plane having signatures of W-O-W symmetric vibration between (700cm-1 and 900 cm−1, somewhat perturbed by the addition of doping. In additions, films show inconsistent variation in electrical resistivity (15–109) Ω-cm due to agglomeration of MWCNTs at grain boundaries and appearance of “nanocracks” due to ionic radii mismatch of tungsten and CNTs at higher doping ratios. Black color films present decrease in optical transmittance for range of 300–400 nm attributed to trapping sites and defects generated due to incorporation of multiwalled CNTs. The splitting of Fermi level as a result of incorporation of MWCNTs caused the increase of band gap energy in range of 3.18 eV, useful in tungsten oxide based new material system which can act as the light harvesting material and energy storage simultaneously.