Light Absorption Characteristics Research Articles

Light absorption properties of elemental carbon (EC) and water-soluble brown carbon (WS–BrC) in the Kathmandu Valley, Nepal: A 5-year study

This study presents a comprehensive analysis of organic carbon (OC), elemental carbon (EC), and particularly the light absorption characteristics of EC and water-soluble brown carbon (WS–BrC) in total suspended particles in the Kathmandu Valley from April 2013 to January 2018. The mean OC, EC, and water-soluble organic carbon (WSOC) concentrations were 34.8 ± 27.1, 9.9 ± 5.8, and 17.4 ± 12.5 μg m−3, respectively. A clear seasonal variation was observed for all carbonaceous components with higher concentrations occurring during colder months and lower concentrations in the monsoon season. The relatively low OC/EC ratio (3.6 ± 2.0) indicates fossil fuel combustion as the primary source of carbonaceous components. The optical attenuation (ATN) at 632 nm was significantly connected with EC loading (ECS) below 15 μg cm−2 but ceased as ECS increased, reflecting the increased influence of the shadowing effect. The derived average mass absorption cross-section of EC (MACEC) (7.0 ± 4.2 m2 g−1) is comparable to that of freshly emitted EC particles, further attesting that EC was mainly produced from local sources with minimal atmospheric aging processes. Relatively intensive coating with organic aerosols and/or salts (e.g., sulfate, nitrate) was probably the reason for the slightly higher MACEC during the monsoon season, whereas increased biomass burning was a major factor leading to lower MACEC in other seasons. The average MACWS-BrC at 365 nm was 1.4 ± 0.3 m2 g−1 with minimal seasonal variations. In contrast to MACEC, biomass burning was the main reason for a higher MACWS-BrC in the non-monsoon season. The relative light absorption contribution of WS-BrC to EC was 9.9% over the 300–700 nm wavelength range, with a slightly higher ratio (13.6%) in the pre-monsoon season. Therefore, both EC and WS-BrC should be considered in the study of optical properties and radiative forcing of carbonaceous aerosols in this region.

Underwater persistent bubble-assisted femtosecond laser ablation for hierarchical micro/nanostructuring

In this study, we demonstrate a technique termed underwater persistent bubble assisted femtosecond laser ablation in liquids (UPB-fs-LAL) that can greatly expand the boundaries of surface micro/nanostructuring through laser ablation because of its capability to create concentric circular macrostructures with millimeter-scale tails on silicon substrates. Long-tailed macrostructures are composed of layered fan-shaped (central angles of 45°–141°) hierarchical micro/nanostructures, which are produced by fan-shaped beams refracted at the mobile bubble interface (≥50° light tilt, referred to as the vertical incident direction) during UPB-fs-LAL line-by-line scanning. Marangoni flow generated during UPB-fs-LAL induces bubble movements. Fast scanning (e.g. 1 mm s−1) allows a long bubble movement (as long as 2 mm), while slow scanning (e.g. 0.1 mm s−1) prevents bubble movements. When persistent bubbles grow considerably (e.g. hundreds of microns in diameter) due to incubation effects, they become sticky and can cause both gas-phase and liquid-phase laser ablation in the central and peripheral regions of the persistent bubbles. This generates low/high/ultrahigh spatial frequency laser-induced periodic surface structures (LSFLs/HSFLs/UHSFLs) with periods of 550–900, 100–200, 40–100 nm, which produce complex hierarchical surface structures. A period of 40 nm, less than 1/25th of the laser wavelength (1030 nm), is the finest laser-induced periodic surface structures (LIPSS) ever created on silicon. The NIR-MIR reflectance/transmittance of fan-shaped hierarchical structures obtained by UPB-fs-LAL at a small line interval (5 μm versus 10 μm) is extremely low, due to both their extremely high light trapping capacity and absorbance characteristics, which are results of the structures’ additional layers and much finer HSFLs. In the absence of persistent bubbles, only grooves covered with HSFLs with periods larger than 100 nm are produced, illustrating the unique attenuation abilities of laser properties (e.g. repetition rate, energy, incident angle, etc) by persistent bubbles with different curvatures. This research represents a straightforward and cost-effective approach to diversifying the achievable hierarchical micro/nanostructures for a multitude of applications.

DNA biodots based targeted theranostic nanomedicine for the imaging and treatment of non-small cell lung cancer

The light absorption and emission characteristics of DNA biodots (DNA-BD), along with biocompatibility, give them a high potential for use in various medical applications, particularly in diagnostic purpose. DNA, under high pressure and temperature, condenses to form luminescent biodots. The objective of this research is to develop DNA-biodots (BD) loaded and cetuximab conjugated targeted theranostic liposomes of etoposide for lung cancer imaging and therapy. Theranostic liposomes were prepared by using the solvent injection method and characterized for their particle size, polydispersity, zeta potential, encapsulation efficiency, and pH-dependent in-vitro release, SEM, TEM AFM, EDX, and XRD. The t50% (time at which 50% of the drug releases from the preparation) of the formulations was pH-dependent, with a significant increase in the release at lower pH (5.5). To kill A549 adenocarcinoma cells, the etoposide (control) required significantly (p < 0.05) higher drug concentrations in comparison to non-targeted and; the non-targeted formulation required more concentrations in comparison to targeted liposomes. The in-vivo results demonstrated that CTX-TPGS decorated theranostic liposomes could be a promising carrier for lung theranostics due to their nano-size and selectivity towards EGFR overexpressed cells which provided an improved NSCLC targeted delivery of ETP in comparison to the non-targeted and control formulations.

Effect of Arbuscular Mycorrhizal Fungi (AMF) and Plant Growth-Promoting Bacteria (PGPR) Inoculations on Elaeagnus angustifolia L. in Saline Soil

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are considered highly-efficient agents for conferring salt tolerance in host plants and improving soil fertility in rhizosphere. However, information about the inoculation of beneficial microbes on halophytes in arid and semi-arid regions remains inadequate. The objective of this study was to evaluate the influence of AMF (Glomus mosseae) inoculation, alone or in combination with PGPR (Bacillus amyloliquefaciens), on biomass accumulation, morphological characteristics, photosynthetic capacity, and rhizospheric soil enzyme activities of Elaeagnus angustifolia L., a typical halophyte in the northwest of China. The results indicate that, for one-year-old seedlings of Elaeagnus angustifolia L., AMF significantly promoted biomass accumulation in aboveground organs, increased the numbers of leaves and branches, and improved the leaf areas, stem diameters and plant height. AMF-mediated morphological characteristics of aboveground organs favored light interception and absorption and maximized the capacities for photosynthesis, transpiration, carbon dioxide assimilation and gas exchange of Elaeagnus angustifolia L. seedlings in saline soil. AMF also promoted root growth, modified root architecture, and enhanced soil enzyme activities. Elaeagnus angustifolia L. was more responsive to specific inoculation by AMF than by a combination of AMF and PGPR or by solely PGPR in saline soils. Therefore, we suggest that G. mosseae can be used in saline soil to enhance Elaeagnus angustifolia L. seedlings growth and improve soil nutrient uptake. This represents a biological technique to aid in restoration of saline-degraded areas.

Engineering the excited state of graphitic carbon nitride nanostructures by covalently bonding with graphene quantum dots

Graphitic carbon nitride (CN) materials have drawn remarkable research attention due to their extraordinary optical properties, which are especially promising for metal-free photocatalysis and photoluminescence. Herein we theoretically study the light absorption, electronic, and excitonic characteristics of covalently hybrid structures of CN quantum dots (CNQDs) and graphene quantum dots (GQDs). Density functional theory (DFT) and time-dependent DFT (TD-DFT) reveal that the relative size of CNQDs and GQDs and chemical modification to GQDs or CNQDs surface are critical determining the absorption and photocatalytic/photoluminescent performances of the as-studied structures. Importantly, the distribution position of the photoexcited electron–hole pair is found to depend on the relative size of CNQDs and GQDs, and chemical groups such as epoxy group may lead to distinct exciton distributions in the CNQD–GQD hybrid structures after attaching them to GQD or CNQD surface as compared to the case of pristine GQD and CNQD, indicating a non-negligible influence of unintended chemical reactions to CNQDs and/or GQDs under working conditions on the efficiencies of the materials for photocatalytic and photoluminescent applications.

Features of light absorption by spherical microcapsules with metal nanoinclusions

Features of light absorption by spherical microcapsules with metal nanoinclusions

Efficient Direct Absorption Solar Collector Using Nanomaterial Suspended Heat Transfer Fluid

Abstract Effective absorption and utilization of incident solar thermal energy in present basic solar collector is primary concern for energy efficient and optimum design due to heat absorption on surface and indirect transfer of heat to fluid medium. Poor absorption ability and transport properties of generally used conventional heat transfer fluid such as water, also limit the heat absorption and transfer efficiency of solar collector. Recently, Stable suspension of nanoparticles into conventional base-fluids has been used that improves the light absorption and thermo physical characteristics of the base-fluid which also results into an upside in the effectiveness of the solar collector. This novel fluid can be utilized for efficient absorption and heat transfer in solar collector. The present paper introduces the idea and design of Direct Absorption Solar Collector (DASC) and use of nano fluid as heat carrying fluid in order to experimentally analyse the developed DASC. The paper also discusses the experimental performance study on this new type of direct absorption solar collector for evaluating the effects of different Alumina nanoparticles concentration in Al2O3-water nanofluid used as a heat carrying fluid. Experimental instantaneous efficiency was calculated for three varying concentrations of Alumina nanoparticles, 10 ppm, 50 ppm and 100 ppm in actual outdoor condition. The results indicated the enhanced efficiency of DASC with Al2O3 nanofluid in comparison to base fluid water. The efficiency enhancement was 22.1%, 39.6% and 24.6% for 10 ppm, 50 ppm and 100 ppm concentration respectively. The promising results will provide potential development of nanofluid based DASC for efficient utilization of solar energy than a conventional solar collector

Fabrication and ultraviolet-visible-near infrared absorption properties of silver nano arrays based on aluminum

In this paper, the highly ordered periodic silver nanosphere arrays are fabricated by vacuum evaporation based on anodic aluminum oxide (AAO) template. The diameter and spacing of silver nanosphere in the arrays are adjusted just by controlling the thickness of evaporation. Furthermore, this can effectively modulate the absorption peaks and bandwidths in ultraviolet-visible-near-infrared regions. The measurement results of absorption spectra show that the nano-arrays have obvious electromagnetic wave absorption characteristics in the ultraviolet, visible and near-infrared bands. The finite-difference time-domain theoretical simulation combined with experiments is used to analyze the physical mechanism of light absorption characteristics in different wavebands. The ultraviolet strong absorption is due to the Fano resonance induced by asymmetric dielectric environment of silver and aluminum; the visible absorption originates from local surface plasmon resonance of silver nanoparticles; the near-infrared strong absorption is attributed to the surface lattice resonance of silver nanosphere arrays.

A Novel nanodiamond/Zinc nanocomposite as potential counter electrode for flexible dye sensitized solar cell

In this study, a novel nanodiamoands (NDs)/zinc (Zn) nanocomposite have been investigated as counter electrode (CE) in flexible dye sensitized solar cell (DSSC) device as potential replacement for platinum (Pt). Simple drop casting method has been employed to fabricate CE on indium tin oxide (ITO) coated Polyethylene terephthalate (PET) substrate. Various concentrations of Zn in optimized NDs layer have been investigated. Scanning electron microscopy (SEM) and X-Ray diffraction (XRD) methods have been utilized to study surface morphology and structural composition. Uv–vis has been employed to study light absorption characteristics. Fourier Transform Infrared (FTIR) has been used to identify redox active functionalities. Electron Impedance Spectroscopy (EIS) and Cyclic Voltametery (CV) have been employed to study electron transfer and catalytic activity and finally I-V testing has been conducted using sun simulator. The optimized layer of NDs displayed 78.52% equivalent performance compared to Pt based CE at optimum layer thickness. The introduction of Zn nanoparticles further improved the catalytic activity comparable or even exceeds the performance of Pt based reference CE. A 6.23% increase in performance has been observed at 8% Zn concentration compared to Pt based reference device. Further increment in concentration leads to reduction in performance due to charge trapping sites and agglomeration of nanoparticles.

Emission characteristics of size distribution, chemical composition and light absorption of particles from field-scale crop residue burning in Northeast China

Crop residue burning in China increased significantly in the last decade, especially it took up a majority in Northeast China, which plays an important role of severe haze pollution. Hence, two main types of crop residues (corn and rice straw) were chosen to characterize the particle number concentration, chemical components of fine particulate matter and optical properties of carbonaceous aerosols by a suite of fast-response online portable instruments, together with offline sampling and analysis, during the field-based combustion experiments in Northeast China. For the range of 250 and 2500 nm, more particles were emitted from rice straw burning than those from corn straw burning, and the time-averaged number concentration of particles during the flaming process was approximately 2 times higher than that during the smoldering process for these two straws. Organic carbon (OC), elemental carbon (EC) and water-soluble ions were the most abundant components and accounted for 42.5 ± 7.5%, 7.7 ± 1.7% and 18.0 ± 3.4% of the PM2.5, respectively. Furthermore, rice straw burning emitted higher OC and lower Cl− and K+ than those from corn straw burning. The average absorption Ångström exponent (AAE) of carbonaceous aerosols was 2.1 ± 0.3, while the AAE of brown carbon (BrC) was 4.7 ± 0.4 during the whole burning process. On average, BrC contributed to 63% and 20% of the total light absorption at 375 nm and 625 nm, respectively. Parameterization of BrC absorption revealed that the fraction of absorption from BrC has a reasonably good correlation with EC/OC (−0.84) and AAE (0.94) at 375 nm. Generally, combustion conditions can affect the optical properties of carbonaceous aerosols, and a negative correlation (−0.77) was observed between the AAE and modified combustion efficiency; in addition, the percentage of absorption due to BrC were lower at the flaming phase.

Two-dimensional photocatalyst design: A critical review of recent experimental and computational advances

In recent years, two-dimensional (2D) semiconductor photocatalysts have been widely applied in water splitting, CO 2 reduction, N 2 fixation, as well as many other important photoreactions. Photocatalysts in the form of 2D nanosheet possess many inherent advantages over traditional 3D nanopowder photocatalysts, including improved light absorption characteristics, shorter electron and hole migration paths to the photocatalysts’ surface (thus minimizing undesirable electron-hole pair recombination), and abundant surface defects which allow band gap modulation and facilitate charge transfer from the semiconductor to adsorbates. When synergistically exploited and optimized, these advantages can impart 2D photocatalysts with remarkable activities relative to their 3D counterparts. Accordingly, a wide range of experimental approaches is now being explored for the synthesis of 2D photocatalysts, with computational methods increasingly being used for identification of promising new 2D photocatalytic materials. Herein, we critically review recent literatures related to 2D photocatalyst development and design. Particular emphasis is placed on 2D photocatalyst synthesis and the importance of computational studies for the fundamental understanding of 2D photocatalyst electronic structure, band gap structure, charge carrier mobility and reaction pathways. We also explore the practical challenges of using 2D photocatalysts, such as their difficulty to synthesize in large quantity and also their characterization. The overarching aim of this review is to provide a snapshot of recent work targeting high-performance 2D photocatalysts for efficient solar energy conversion, thus laying a firm base for future advancements in this rapidly expanding area of photocatalysis research.

Characterizing DOC sources in China’s Haihe River basin using spectroscopy and stable carbon isotopes

The Haihe River Basin is a polluted area affected by the developing industry and intensive agricultural activities in China. Dissolved organic matter (DOC) and light-absorbing characteristics of chromophoric dissolved organic matter (CDOM) were monitored in different tributaries of China within the Haihe River basin during spring and autumn. The concentration of DOC during spring was higher than during autumn (p < 0.01), and the evaporation was an important factor affecting the concentration of DOC in the basin. By contrast, the proportion of inputs due to terrigenous plants during autumn was higher than during spring. Carbon stable isotope analysis δ13C and C: N ratio of DOC, evidenced the inputs of DOC in the Haihe River basin from different sources including sewage, terrestrial plants, soil, and plankton. Isotopic analysis of δ13C and excitation-emission matrix (EEM) with fluorescence regional integration (FRI) analysis supported the hypothesis that allochthonous inputs contributed substantially to the inputs of DOC in the Haihe River basin, coming largely from sewage (9.8%–81.2%) and terrestrial plants (13.3%–65.8%). Depending on the source of DOC and contribution, four types with different EEM spectra were set. Type I, river water from sewage (81.2%); Type II, river water with input from terrestrial plants (65.8%); Type III, river water with plankton (36.4%), and Type IV, river water with soil-derived DOC (33.9%). The results demonstrated that the combined methodology using 13C stable isotope and EEM-FRI can be used to characterize the components of DOC in river waters. This approach was important for tracking the concentration and composition of DOC in river waters from different input sources and for better understanding concerning the local regulation of the terrestrial carbon cycle.

High performance phototransistors with organic/quantum dot composite materials channels

Abstract Nanomaterials, especially quantum dots, have become one of the most great potential channel transport layer materials in the field of photo detection mainly due to their particular light absorption characteristics. However, there are still many disadvantages such as low carrier transport capability possibly attributable to the discontinuity nature of materials. Therefore, particular phototransistors with pentacene/CdSe@ZnS QDs composite materials channels have been prepared by simply blending and spin-coating 6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and QDs solution in weight ratio of 3:1. The particular device architecture with organic/quantum dot composite materials channels effectively combined the high carrier mobility advantage of organic semiconductors with the strong absorption characteristic of quantum dots in specific optical band regions and further overcame the low conductivity shortcomings of pure quantum dot materials. The device with particular pentacene/CdSe@ZnS QDs composite channel exhibited excellent electrical and optical properties with current switch ratio Ion/off of 104, carriers mobility of ~0.161 cm2/V, photosensitivity P of 105, responsivity R of 0.33 mA/W and detectivity D of 1.48 × 1011 Jones at drain voltage of −35 V and light intensity of 1.6 mW/cm2, respectively, indicating that this composite, as one of the most promising channel transport layer material candidates for photodetector, provides one chance to improve the characteristic of photodetector transistors just by using hybrid channel technology.

Mesoporous monolith designs of mixed phased titania codoped Sm3+/Er3+ composites: A super responsive visible light photocatalysts for organic pollutant clean-up

In this work, we report on the synthesis of a new class photocatalyst material of Sm3+/Er3+ codoped TiO2 mesoporous monolithic network using a surfactant mediated microemulsion micro-phased sol-gel technique. The crack-free monoliths were characterized using, XRD, SEM-EDX, TEM-SAED, XPS, UV–Vis-DRS, PLS, TG-DTA, FT-IR, Raman, and BET analysis. The study revealed that the stoichiometric mixed dopant composite of Sm3+ and Er3+ with TiO2 exhibited excellent visible light photocatalytic activity. The XRD data showed that the Sm3+/Er3+ codoped TiO2 monolith exhibited a mixed phase ((75%) anatase - (25%) rutile) crystallinity, with well-defined mesopores. The TEM and SEM images confirmed the existence of a uniform pattern of highly ordered worm-like structure of mesoporous design, which corroborates with the absorption-desorption isotherm pattern. The XPS spectra confirmed the trivalent state of the Sm-Er composite, and their surface dispersion onto the Ti-O-Ti lattice. The UV–Vis-DRS analysis showed an energy band gap value of 3.26, 3.02, and 2.80 eV, for undoped, (3.0 mol%) Sm3+ doped, and (0.6 mol%) Er3+/(3.0 mol%) Sm3+ codoped TiO2 monoliths, respectively, which reflected on the visible light absorption characteristics of the Sm3+/Er3+ doped TiO2 composite. The photo-luminescence emission spectra showed that the (0.6 mol%) Er3+/(3.0 mol%) Sm3+ composite as the best performing visible light photocatalyst. The efficacy of the proposed class of photocatalytic materials was investigated for textile dye degradation using Acid Blue 113, as the model organic dye pollutant, which was dissipated within 30 min of visible light irradiation. For the superior performance of the photocatalyst, the operational parameters such as, solution pH, dopant/co-dopant stoichiometry, photocatalyst quantity, dye concentration, light intensity, photooxidizers, degradation kinetics, reusability, etc., were studied and optimized. The dye degradation was monitored using UV–Visible spectrophotometry, and the extent of dye mineralization was confirmed by TOC analysis.

Using Polymers and Pigments to Produce Laser Interference Rings

When a laser of sufficient intensity is shined into a pigmented transparent medium, the partially absorbed laser light can heat and change the refractive index of the medium in the path of the beam. This altered medium will in turn cause the transmitted laser light to thermally defocus into a series of concentric rings. Some solvents such as 2-propanol and a variety of polymers such as polystyrene, polyethylene terephthalate, and polydimethylsiloxane can be pigmented with a variety of colors. Samples of various colors can be used to spectacularly demonstrate characteristics of light absorption. For example, a 2-propanol solution containing methyl red in red acidic form will absorb a green laser and produce interference rings, but a solution of methyl red in yellow basic form will not. As another example, a red laser beam will pass unaffected through a red pigmented film, but the beam will heat a green film (e.g., from a green pigmented polyethylene terephthalate soda bottle) to produce interference rings. Additionally, since the pattern produced is based on the interference of light waves, these demonstrations reinforce concepts associated with the wave nature of light.

Spectroscopic Ellipsometry of Asphalt Binder: A Study of Optical Constants

Spectroscopic ellipsometry is a powerful technique for determining optical properties of any thin surface. A method for characterizing optical properties of warm asphalt binder using spectroscopic ellipsometry along with associated results has been presented in this paper. Thin films of warm asphalt binders were produced using LEADCAP and Sasobit and characterized using a variable angle spectroscopic ellipsometry. Refractive index and extinction coefficient of each of the samples (original and aged) were extracted from model fitted spectra. Clear variation in refractive index and extinction coefficient was observed among the samples before and after aging. The samples were found to be highly reflective with refractive index ‘n’ in the range 1.55–1.62 and extinction coefficient ‘k’ in the range of 0.01–0.06, both before and after aging. Reflectivity of PG 64-22 with LEADCAP exhibited the highest refractive index and the lowest extinction coefficient in visible wavelength of light among the samples. The results indicated that the highest reflection of visible light can be observed from LEADCAP-modified binder. Cracking properties and absorption coefficient of the binders are observed to have a correlation. The method reported here can be applied to any type of asphalt binder to determine its light absorption and reflection characteristics for a wide range of wavelength.

In situ synthesis of multi-functional gelatin/resorcinol/silver nanoparticles composite films

Abstract Silver nanoparticles (AgNP) were synthesized in situ by reducing AgNO3 using resorcinol and gelatin to prepare functional gelatin/resorcinol/AgNP nanocomposite films (Gel/Res/AgNP). The nanocomposite film exhibited a characteristic light absorption peak of AgNP at 420 nm and improved UV-light barrier property. X-ray diffraction (XRD) results also showed a characteristic reflection peak of crystalline AgNP around 2θ = 38° corresponding to the (111) diffraction plane of AgNP. The water vapor permeability (WVP), water contact angle (WCA), surface morphology and thermal stability of the composite films were not affected, but the tensile strength (TS) of the composite film decreased and the elongation at break (E) increased by the formation of AgNP. The Gel/Res/AgNP nanocomposite film showed a strong antioxidant property with high DPPH and ABTS free radical scavenging activity. Also, the Gel/Res/AgNP nanocomposite films exhibited strong antimicrobial activity against foodborne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. The developed Gel/Res/AgNP composite films with potent antimicrobial and antioxidant activities have a high potential to be used in food packaging to increase the shelf life of packaged food.

Hybrid graphene metasurface for near-infrared absorbers.

We experimentally demonstrated an amorphous graphene-based metasurface yielding near-infrared super absorber characteristic. The structure is obtained by alternatively combining magnetron-sputtering deposition and graphene transfer coating fabrication techniques. The thickness constraint of the physical vapor-deposited amorphous metallic layer is unlocked and as a result, the as-fabricated graphene-based metasurface absorber achieves near-perfect absorption in the near-infrared region with an ultra-broad spectral bandwidth of 3.0 µm. Our experimental characterization and theoretical analysis further point out that the strong light-matter interaction observed is caused by localized surface plasmon resonance of the metal film's particle-like surface morphology. In addition to the enhanced light absorption characteristics, such an amorphous metasurface can be used for surface-enhanced Raman scattering applications. Meanwhile, the proposed graphene-based metasurface relies solely on CMOS-compatible, low cost and large-area processing, which can be flexibly scaled up for mass production.

Optical sensor based on dye-sensitized solar cell with tobacco chlorophyll

Modified optical sensor based on dye-sensittized solar cell has been successfully fabricated to measure the number of light energy. The electric parameters as the sensor output were achieved from the light illuminance as the sensor input. The measured parameter from optical sensor according to the voltage and current output have been characterized to obtain the sensor performance. In this research, the modified sensor is customized from dye-sensitized solar cell with extracted tobacco chlorophyll dye as the photo-catalysator, photo-electrode of titanium dioxide and Iodine solution for redox reaction. The thick layer deposition with selected material is conducted using spin coating method of 1000 rpm. Based on the absorbance measurement, it shows that tobacco dye has the characteristics of visible light absorption in the wavelength of visible light spectra. The analytical result shows that the sensor has the wide linear characteristic in certain light illuminance and the increasing light intensity produces higher electrical parameter output both current and voltage. This sensor has potential prospect to be used as a light sensor and to be competitive fabrication cost.

Chemical and physical characteristics of hydroxyl group-modified multi-walled carbon nanotube-combined DNA layers

In order to enhance the applicability and functionality of DNA-based complexes, we introduced hydroxyl (–OH) group-modified multi-walled carbon nanotubes (MWCNT–OH), which can aid the dispersion and adsorption in the DNA template. Herein, we fabricated MWCNT–OH-combined DNA and cetyltrimethyl-ammonium chloride-modified DNA (DNA-CTMA) layers using the solution-processed method. The distinct chemical and physical characteristics of the MWCNT–OH-combined DNA and DNA-CTMA layers were examined through various characterisation techniques. For instance, the elemental and surface characteristics were analysed by energy-dispersive x-ray spectroscopy, field emission scanning electron microscopy, and atomic force microscopy. The charge transfer was examined by x-ray photoelectron spectroscopy. In the x-ray photoelectron spectra, a negative peak shift was observed, indirectly indicating that the charge transfer from MWCNT‒OH to DNA occurred. The vibrational and rotational modes were analysed by Raman spectroscopy, and the characteristic functional group and molecular interaction were examined using Fourier transform infrared spectroscopy. As expected, we observed four major characteristic Raman bands of MWCNT–OH in the DNA and DNA-CTMA layers which corresponded to the D-, G-, and G′-bands as well as the strain-induced band. Finally, the light absorption, photoluminescence, and electrical characteristics were examined using UV–vis–NIR spectroscopy, a photoluminescence mapper, and a probe station, respectively. The absorption in the full spectral range, photoluminescence quenching, and current enhancement of DNA and DNA-CTMA layers combined with MWCNT–OH were influenced by the electrostatic and van der Waals interactions between MWCNT–OH and DNA (DNA-CTMA). Our results will provide a simple protocol for constructing composite layers made of organic and inorganic materials which show novel characteristics with easy controllability.