Modified TiO2 (black TiO2) nanoparticles (NPs) produced by different methods showed enhanced visible light absorption than ordinary white TiO2 NPs. Pulsed laser ablation in liquid (PLAL) is a ...promising technique for synthesizing nanostructures due to its simplicity, less usage of toxic reagents and absence of costly vacuum systems. In the present study, black TiO2 NPs synthesized by pulsed laser irradiation is examined for their structure, morphology and optical properties. Nanoparticles of modified TiO2 were prepared by pulsed laser ablation in liquid technique by irradiating white TiO2 powder in water using an Nd:YAG laser (532 nm, 10 ns, 10 Hz). Characterization of morphology of the nanoparticles by scanning electron microscopy (SEM) showed a change in morphology by laser irradiation for TiO2 nanoparticles. Crystalline structure was determined by X-ray diffraction (XRD) in which the major anatase phase in white TiO2 was changed to rutile during irradiation and for longer irradiation, rutile became the major phase. Most of the vibrational peaks for TiO2 were identified in Raman spectra. Ti 2p and O 1s binding energy analysis by X-ray photoelectron spectroscopy (XPS) for black TiO2 (90 min) showed changes of 0.5 eV and 0.7 eV respectively compared to the white TiO2 due to their change in chemical states. Optical absorption and band gap evaluation were done using the diffuse reflectance spectra measurements that showed enhanced absorption in the visible range for all the laser irradiated nanoparticles and a decrease in the bandgap from 2.98 eV of white TiO2 to 1.84 eV for black TiO2. Synthesis of black TiO2 at normal atmospheric conditions by irradiation of TiO2 in liquid using 532 nm laser output which is a very common Nd:YAG wavelength is reported for the first time.
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•Black TiO2 NPs were prepared by 532 nm laser irradiation of TiO2 for first time.•Laser irradiation caused a change from anatase to rutile for the black TiO2 NPs.•Black TiO2 NPs showed enhanced visible light absorption.•XRD and Raman confirmed the phases present in white as well as black TiO2.•XPS analysis confirmed the composition and chemical states of black TiO2.
Herein, we report a promising solution-processing method for the controlled incorporation of germanium (Ge) into Cu2ZnSnS4 (CZTS) films using a nontoxic molecular ink. The effect of Ge concentration ...on structural, optical, electrical and electronic properties of the films were systematically investigated. The successful Ge alloying in CZTS was confirmed by XRD analysis and exploring the sensitivity of Raman scattering. The as-synthesized Cu2ZnSn1-xGexS4 (CZTGS; x = 0, 0.1, 0.15, 0.2 and 0.25) films exhibit strong absorption in the visible region with the gradual increment in the band gap energy from 1.46 to 1.61 eV by increasing x from 0 to 0.25. A decrease in Urbach energy at higher Ge/Sn + Ge ratio supports the reduction of overall disorder into the system. The information about the correct oxidation states of the constituent elements and optimal chemical composition of the CZTGS films was obtained from X-ray photoelectron spectroscopy (XPS). The decrease in SnII/SnIV signal ratio with the increase in Ge further supports the suppression of deep-trap SnZn antisite defects. The XPS valence band spectra reveal that the position of valence band maximum ascended from 0.09 to 0.15 eV with increasing Ge content in the films. Several relevant optical constants were determined of the CZTGS films which are important for applications in solar cell devices as well as for simulation purpose.
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•Highly stable Cu2ZnSn1−xGexS4 (0 ≤ x ≤ 0.25) thin films were obtained by molecular ink approach.•Ge incorporation in kesterite lattice reduces the Urbach energy.•Dielectric loss in kesterite films is decreased by increasing Ge/Sn ratio.•XPS valence band spectra reveals the ascendance of valence band maximum with Ge.
The increasing energy demand and the limitations of the existing technologies due to the scarcity, cost and toxicity of the materials urge the researchers to hunt for efficient thin film solar cells ...based on earth-abundant, inexpensive and less toxic materials. For a decade, binary and ternary antimony based sulfides have gained attention due to their possible applications in solar cells. This interest is the basis of this review. In this review article, we describe basic properties of copper antimony sulfide (CuSbS
2
) thin films to investigate their photovoltaic applications. A detailed description of the preparation methods, studies on morphologies and optoelectronic properties based on published work, including our experience are presented. A systematic review is done to demonstrate emerging interest in the photovoltaic performance of this compound. This review gives an in depth discussion on the structure, morphology, optical and electrical properties of copper antimony sulfide thin films.
To develop and evaluate the effectiveness of a home based intervention in reducing caregiver burden, promoting caregiver mental health and reducing behavioural problems in elderly persons with ...dementia.
This was a randomised controlled trial in which the person with dementia-caregiver dyad was randomly allocated either to receive the intervention immediately or to a waiting list group which received the intervention after 6 months. It was carried out in communities based in two talukas (administrative blocks) in Goa, India. Mild to moderate cases with dementia (diagnosed using the DSM IV criteria and graded using the Clinical Dementia Rating scale) and their caregivers were included in the trial. Community based intervention provided by a team consisting of Home Care Advisors who were supervised by a counselor and a psychiatrist, focusing on supporting the caregiver through information on dementia, guidance on behaviour management, a single psychiatric assessment and psychotropic medication if needed. We measured caregiver mental health (General Health Questionnaire), caregiver burden (Zarit Burden Score), distress due to behavioural disturbances (NPI-D), behavioural problems in the subject (NPI-S) and activities of daily living in the elder with dementia (EASI). Outcome evaluations were masked to the allocation status. We analysed each outcome with a mixed effects model. 81 families enrolled in the trial; 41 were randomly allocated to the intervention. 59 completed the trial and 18 died during the trial. The intervention led to a significant reduction of GHQ (-1.12, 95% CI -2.07 to -0.17) and NPI-D scores (-1.96, 95%CI -3.51 to -0.41) and non-significant reductions in the ZBS, EASI and NPI-S scores. We also observed a non-significant reduction in the total number of deaths in people with dementia in the intervention arm (OR 0.34, 95% CI 0.01 to 1.03).
Home based support for caregivers of persons with dementia, which emphasizes the use of locally available, low-cost human resources, is feasible, acceptable and leads to significant improvements in caregiver mental health and burden of caring. ClinicalTrials.gov NCT00479271.
•Graphene incorporated indium sulphide thin films by combination of two methods.•Structure, morphology and composition analysis are done.•Resistance decreases due to graphene incorporation from ohmic ...characterestics.•Better thermal stability is achieved due to graphene incorporation.•Lower optical bandgap with enhanced absorption due to the introduction of graphene.
Indium sulphide (In2S3) is a versatile material having applications in optoelectronics and photovoltaics, whose properties could be tailored by incorporation or doping. We report incorporation of graphene in indium sulphide (In2S3-Gr) thin films by two step process. The pure samples are synthesized by chemical bath deposition. Incorporation of graphene in these thin films is done by spin coating followed by annealing. Structural analyses of pure and In2S3-Gr thin films are carried out by using Grazing Incidence X-Ray Diffraction, Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman spectroscopy. In this work, investigations on electrical, thermal and optical properties of In2S3-Gr thin films are also conducted. The systematic characterisations revealed that In2S3-Gr nanocomposite thin films are synthesized by this process. Also, the samples showed significant modifications in its structural and optoelectronic properties by incorporation of graphene. In2S3-Gr thin films prepared could be useful in various optoelectronic devices including photovoltaics and as a photocatalyst.
In this work, nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by pulsed laser ablation in liquid using Nd:YAG laser (532 nm). Graphite target was ablated in dimethylformamide, as ...solvent and nitrogen source, and the microstructure as well as optical properties of N-GQDs were studied. The N-GQDs structure consists of a graphitic core with oxygen and nitrogen functionalities and particle size about 3 nm, as demonstrated by X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The as-prepared N-GQDs structure was modified by solvothermal treatment at 65, 90 and 120 °C reducing the oxygen functional groups, adding nitrogen and restoring the π-conjugated structure of N-GQD. The N-GQDs exhibit UV–Vis absorption spectrum with the characteristic π-π* and n – π* electronic transitions of the GQDs with a large amount of oxygen and nitrogen functionalities. These N-GQDs exhibited a visible light photoluminescence centered at 486 nm upon an excitation of 410 nm and the photoluminescence intensity enhanced up to 4.05% of quantum yield after solvothermal treatment. The N-GQDs dispersion was used for selective detection of ascorbic acid, through a signal-off and signal-on system. The results show the use of N-GQDs as a competent photoluminescence sensor for metal ions and ascorbic acid.
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In our present study we focus on characterizing copper oxide (CuO) thin films synthesized at various substrate temperatures and to assess the electrochemical performance of the optimized sample. The ...spray pyrolysis method was used to fabricate CuO thin film samples, with the substrate temperatures ranging from 250 to 400 °C. The coatings underwent characterization through different analytical techniques, including X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Raman spectroscopy, and Hall effect measurements. All the thin film samples were confirmed to have a monoclinic phase. The presence of Cu=O was confirmed by Raman spectroscopy. All the samples exhibited P type conductivity except the one synthesized at 400 °C. Galvanostatic charge–discharge studies revealed a pseudocapacitive nature for the optimized sample synthesized at 350 °C. The symmetrical charging and discharging curves imply excellent material reversibility, indicating long-term cyclic stability. The Nyquist plot exhibited a semicircle at high frequencies, representing the material’s intrinsic resistance and a linear behavior at low frequencies, depicting the ion transfer resistance. The electrode demonstrated favorable electrochemical properties and potential use of the material in supercapacitor applications.
Ternary chalcostibite copper antimony sulfide (CuSbS
) is an emerging semiconductor material having applications in photovoltaics, energy storage and optoelectronics due to its high absorption ...coefficient, suitable bandgap, and it consists of non-toxic and earth abundant elements. CuSbS
thin films are prepared by combining chemical bath deposition (antimony sulfide (Sb
S
)) and thermal evaporation (copper (Cu)) followed by a heat treatment and their application as visible to near infrared photodetectors is reported. Crystalline structure, elemental composition, chemical state, morphology and optoelectronic properties of the films were characterized by various techniques. The effect of three different Cu thicknesses (CAS 20, CAS 30 and CAS 40 nm) on the photodetection properties are evaluated under illumination using light emitting diodes (LEDs) and a laser. The photodetectors fabricated are successfully tested under different wavelengths, power densities and applied voltage and their photoresponse cyclic stability for each wavelength of illumination was recorded. From the sensitivity calculations, the sample with 20 nm Cu thickness (CAS 20) showed higher detection sensitivity for visible to near infrared wavelengths. Better responsivity results were obtained for CAS 40 because of its improved crystallinity and phase purity. Photodetector properties such as sensitivity and responsivity are evaluated for all the samples. These results are beneficial for cost effective and environment friendly photodetectors and optoelectronic devices based on CuSbS
thin films.
Cobalt oxide (Co
3
O
4
), a transition metal oxide known for its favourable capacitive properties and surface characteristics, is a promising candidate for electrode materials in supercapacitive ...energy storage applications. This study presents a comprehensive analysis of cobalt oxide nanoparticles synthesized through the hydrothermal method at varying synthesis temperatures, focusing on their structural, optical, electrochemical, and surface properties. X-ray diffraction analysis confirmed the cubic spinel structure of Co
3
O
4
, while Raman spectroscopy verified the phase composition of the nanoparticles. X-ray photoelectron spectroscopy offered insights into the near-surface chemistry of the synthesized material. The study determined two direct bandgaps of Co
3
O
4
through absorption spectra and Tauc plots. To assess surface morphology and particle size distribution, field-emitting scanning electron microscopy and transmission electron microscopy were employed. Electrochemical investigations involved cyclic voltammetry and Nyquist plots, while galvanostatic charge–discharge tests demonstrated a specific capacitance (
C
sp
) of 450 Fg
−1
at 1 Ag
−1
. Impedance analysis indicated favourable capacitive behaviour with low charge transfer resistance. Furthermore, the study observed cyclic stability with a capacitive retention rate exceeding 88% at a current density of 20 Ag
−1
over 10,000 cycles. The paper also discusses the capacitive and diffusion-controlled charge storage mechanisms at lower scan rates, emphasizing the potential of Co
3
O
4
nanoparticles as the electrode material in the development of supercapacitor devices.
Copper antimony sulfide (CuSbS2) thin films were prepared by annealing and rapid thermal processing (RTP) of Sb2S3–Cu precursor layers at different conditions. Sb2S3 thin films (200nm) were deposited ...by chemical bath deposition from a solution containing SbCl3 and Na₂S₂O₃. Copper layers were thermally evaporated onto the Sb2S3 thin films. A systematic study was done by varying Cu layer thickness as well as the heating conditions. Cu thickness was varied from low (<10nm) to 100nm and the heating conditions were annealing at 380°C, RTP at 500/600°C and annealing at 380°C followed by RTP. The thin films formed at different conditions were analyzed using different techniques to determine their crystalline structure, morphology, elemental composition, chemical state and physical properties. For the given Sb2S3 thickness, Cu 50nm was identified as the effective Cu thickness for the formation of CuSbS2. The CuSbS2 thin films formed at different conditions were incorporated in photovoltaic structures of superstrate configuration: Glass/ITO/CdS/CuSbS2. The best photovoltaic parameters obtained were Voc=665mV, Jsc=1.35mA/cm2, FF=0.62 and η=0.6% measured under illumination using AM1.5 radiation from a solar simulator. Voc and FF are the highest values ever reported for the CuSbS2 based solar cells. The present work strengthens the research activities to improve CuSbS2 based photovoltaic performance, and thus PV technologies using earth abundant and non-toxic materials.
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•CuSbS2 thin films by annealing and rapid thermal processing of Sb2S3-Cu.•The films exhibit direct bandgap 1.5–1.6eV and p-type conductivity.•Glass/ITO/CdS/CuSbS2 PV structure performance of Voc=665mV and FF=0.62.
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