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Si-doping effect on solution-processed In-O thin-film transistors
摘要： In this work, silicon-doped indium oxide thin-film transistors (TFTs) have been fabricated for the first time by a solution processing method. By varying the Si concentration in the In2O3-SiO2 binary oxide structure up to 15 at.%, the thicknesses, densities, and crystallinity of the resulting In-Si-O (ISO) thin films were investigated by X-ray reflectivity (XRR) and X-ray diffraction techniques, while the produced TFTs were characterized by a conventional three-probe method. The results of XRR analysis revealed that the increase in the content of Si dopant increased the thickness of the produced film and reduced its density, and that all the Si-doped ISO thin films contained only a single amorphous phase even after annealing at temperatures as high as 800 °C. The manufactured ISO TFTs exhibited a reduction in the absolute value of threshold voltage VT close to 0 V and low current in the off-state, as compared to those of the non-doped indium oxide films, due to the reduced number of oxygen defects, which was consistent with the behavior of ISO TFTs fabricated by a sputtering method. The ISO TFT with a Si content of 3 at.% annealed at 400 °C demonstrated the smallest subthreshold swing of 0.5 V/dec, VT of ?5 V, mobility of 0.21 cm2/Vs, and on/off current ratio of about 2×107.
关键词： silicon-doped indium oxide,solution processing,amorphous oxide semiconductor,thin-film transistor,spin coating
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [Author(s) 3RD INTERNATIONAL SCIENCES, TECHNOLOGY & ENGINEERING CONFERENCE (ISTEC) 2018 - MATERIAL CHEMISTRY - Penang, Malaysia (17–18 April 2018)] - Synthesis of gold nanoparticles (AuNPs) onto anodized titania nanotubes (TNTs) by spin coating technique
摘要： Gold nanoparticles (AuNPs) have received copious interests due to their unique properties such as small in size, reactive, high surface area and can be potentially applied in myriad fields including physics, chemistry, medicine and material sciences. However, the nanosized of gold particles makes them very reactive and undergo aggregation without protection. For that reason, supporting materials are introduced to prevent the aggregation of the AuNPs. In particular, metal oxide for example, titanium dioxide or titania nanotubes (TNTs) has been used as a support material because of its inertness, high porosity and great surface areas. Nevertheless, achieving precise control of attachment AuNPs on the TNTs substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work, a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto fabricated electrochemically-anodized TNTs by a spin coating technique. This preliminary work used different spin rate of 500, 1000 and 2000 revolutions per minute (rpm), following by heat treatment at 250 °C for 2 hours. The FESEM micrograph showed the anodized TNTs with good morphological structures were successfully fabricated at a voltage of 50 V in a mixture of ethylene glycol containing 0.5 wt. % ammonium fluoride solution, with an average nanotubes diameter of 150 nm. Meanwhile, the attachment of AuNPs on the fabricated TNTs has been effectively achieved at a higher spin rate of 2000 rpm and the EDX analysis confirmed the deposition of AuNPs over the TNTs. The AuNPs-TNTs also were tested for the catalytic reduction of p-nitrophenol (p-NP), in which is discussed shortly in this paper.
关键词： Gold nanoparticles,spin coating,titania nanotubes,electrochemical anodization
更新于2025-09-23 15:21:01
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Probing of Thermal Transport in 50-nm Thick PbTe Nanocrystal Film by Time-Domain Thermoreflectance
摘要： Bottom-up fabrication of thermoelectric (TE) materials from colloidal nanocrystal (NC) building blocks can substantially increase their TE efficiency, e.g., by reducing lattice thermal conductivity. In this work, 10-nm spherical phase-pure oleate-capped PbTe NCs with narrow size distribution were synthesized and employed to fabricate 50-nm thick films on insulating SiO2/Si substrates. The spin-coating, with subsequent ligand exchange procedure, was applied to enhance coupling interactions between the NCs. Using dark conductivity measurements, we confirmed the semiconducting behavior and the Schottky-type electrical field-dependent conductivity mechanism in the resultant thin films. The thermal transport in the thin-film was probed by means of a time-domain thermoreflectance (TDTR) method. For this purpose, we used a customized state-of-the-art system based on a picosecond thermoreflectance instrument, which enables area-selective analysis with spatial resolution down to 5 μm. The results show that as-fabricated PbTe NC films exhibit ultralow thermal conductivity of 0.9 W m–1 K–1 at 300 K. The transport property findings suggest potential in the proposed quick and cost-effective spin-coating strategy for bottom-up fabrication of nanostructured TE films from high-quality colloidal NC building blocks.
关键词： colloidal nanocrystals,spin-coating,thermoelectric materials,thermal conductivity,time-domain thermoreflectance,PbTe
更新于2025-09-23 15:21:01
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Higha??Performance Pseudoplanar Heterojunction Ternary Organic Solar Cells with Nonfullerene Alloyed Acceptor
摘要： The vast majority of ternary organic solar cells are obtained by simply fabricating bulk heterojunction (BHJ) active layers. Due to the inappropriate distribution of donors and acceptors in the vertical direction, a new method by fabricating pseudoplanar heterojunction (PPHJ) ternary organic solar cells is proposed to better modulate the morphology of active layer. The pseudoplanar heterojunction ternary organic solar cells (P-ternary) are fabricated by a sequential solution treatment technique, in which the donor and acceptor mixture blends are sequentially spin-coated. As a consequence, a higher power conversion efficiency (PCE) of 14.2% is achieved with a Voc of 0.79 V, Jsc of 25.6 mA cm?2, and fill factor (FF) of 69.8% compared with the ternary BHJ system of 13.8%. At the same time, the alloyed acceptor is likely formed between two the acceptors through a series of in-depth explorations. This work suggests that nonfullerene alloyed acceptor may have great potential to realize effective P-ternary organic solar cells.
关键词： ternary organic solar cells,sequential spin-coating,pseudoplanar heterojunctions,nonfullerene alloyed acceptors
更新于2025-09-23 15:19:57
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High-Performance Perovskite-Based Light-Emitting Diodes from the Conversion of Amorphous Spin-Coated Lead Bromide with Phenethylamine Doping
摘要： Large-grained and well-oriented methylammonium lead tribromide (MAPbBr3) perovskite was formed from the conversion of amorphous lead bromide (PbBr2) doped with phenethylamine (PEA). The addition of PEA ions (with an optimized molar ratio of 0.008%) to the PbBr2 solution assisted the formation of a smooth PEA-doped PbBr2 layer by spin-coating. Then, the PEA-doped PbBr2 thin film would convert into large-grained and well-oriented MAPbBr3 with the help of a solid?vapor reaction under a vaporized methylammonium bromide (MABr) and choline chloride (CC) atmosphere. Furthermore, both PEA and CC would passivate the defects of perovskite to improve the crystal quality of perovskite. By applying this perovskite layer in perovskite light-emitting diodes (PeLEDs), the maximum luminance and current efficiency of PeLEDs could reach 20,869 cd/m2 and 3.99 cd/A, respectively; these values are approximately five and three times larger than those of PeLEDs without PEA. The perovskite converted from spin-coated PbBr2 with a PEA dopant remarkably improved the luminance and current efficiency of its PeLEDs.
关键词： choline chloride,methylammonium lead tribromide,perovskite,phenethylamine,lead bromide,light-emitting diodes,spin-coating
更新于2025-09-23 15:19:57
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Effects of alkali and transition metal-doped TiO <sub/>2</sub> hole blocking layers on the perovskite solar cells obtained by a two-step sequential deposition method in air and under vacuum
摘要： Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications. In this work, the effect of alkali and transition metal-doped TiO2 (cesium-doped TiO2 (Cs-TiO2) and yttrium-doped TiO2 (Y-TiO2)) compact layers on the optical, structural and the photovoltaic performance of the PPSCs have been investigated. The perovskite layer syntheses were carried out by depositing a lead iodide (PbI2) layer via spin-coating; converting PbI2 into methyl ammonium iodide (CH3NH3PbI3) by chemical vapor deposition (CVD) and spin-coating at 60 min and 60 s conversion times respectively. The as-deposited PPSCs were studied layer-by-layer using an X-ray diffractometer, scanning electron microscope, and UV-vis diffuse reflectance, transmittance and absorbance. The power conversion efficiency for stable processed perovskite solar cells were 3.61% and 12.89% for air and vacuum processed, respectively.
关键词： TiO2 doping,Chemical vapor deposition,Perovskite solar cells,Spin-coating,Photovoltaic performance
更新于2025-09-23 15:19:57
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The effect of the spinning speed variation on the perovskite solar cell efficiency
摘要： In this work, compact titanitum dioxide (c-TiO2), amorphous titanitum dioxide (mp-TiO2) and methylammonium lead iodide (CH3NH3PbI3) films were prepared by spin coating method under different different rotational speed of the CH3NH3PbI3 films. Many characterization measurements were achieved on the deposited CH3NH3PbI3 films in order to study the change that resulted from different parameters. The X-ray diffraction (XRD) measurements revealed that the lattice constants of the fabricated CH3NH3PbI3 films were close to the slandered values. The atomic force microscopy (AFM) measurements were conducted in order to study the morphology of the fabricated CH3NH3PbI3 films at different scale, these results displayed that the grain size of the CH3NH3PbI3 films in the range between about 160nm to 210 nm. The field emiision scanning electron microscopy (FE-SEM) results of the fabricated CH3NH3PbI3 films were well agreed to the AFM result especially in the grains shape and distribution. Transmittance measurements have been done to determine the variation of the energy gap and absorption coefficient the CH3NH3PbI3 films. The structure form of the perovskite solar cells were FTO/c-TiO2/mp-TiO2/CH3NH3PbI3/Au, the C-V measurements were achieved to determine the built-in potential, which found to have the highest value when using 4000 rpm during the synthesis of the perovskite layer. In addition, the I-V measurements in dark conditions have been conducted to compute the ideality factor and the saturation current, which are considered important parameters that influences the characteristics of the solar cells. The best solar cell efficiency was obtained at spinning speed of 4000 rpm.
关键词： CH3NH3PbI3,efficiency,spin coating,perovskite solar cell,spinning speed
更新于2025-09-23 15:19:57
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Influence of the modification of annealing parameters on solution-processed metal oxide ETL buffer layers, and a comparative study of spin-coated and thermally evaporated MoOx HTL for use in an inverted polymer solar cell
摘要： Transparent metal oxide thin films were synthesized on indium tin oxide (ITO) substrates via the sol-gel spin coating method using various precursor solutions. The types of metal oxides investigated were zinc oxide (ZnO), titanium dioxide (TiO2) and molybdenum oxide (MoOx) whose purpose was to serve as buffer layers in organic solar cells. ZnO and TiO2 layers were to serve as electron transport layers (ETL), and the MoOx layer served as a hole transport layer (HTL). Compared to conventional ordering, in this set-up, the sequence of the buffer layers is inverted to improve the stability of the polymer solar cells. The annealing temperature during the preparation of the ETL metal oxide layers was varied in order to investigate the effect on the morphological properties of the thin films. The HTL layer was both spin-coated and thermally evaporated and the results were compared. The surface morphology and elemental analysis of the prepared samples were studied using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) capability. The optical properties were investigated by UV–Vis spectroscopy and it was found that the metal oxide layers have high optical transparency in the visible range, as required. The crystal structures of the prepared metal oxides were investigated by X-ray diffraction (XRD). A comparative study on the effect of the ETLs individually in solar cells was done by incorporating them individually with active layers of blends of poly (3-hexylthiophene) (P3HT), as electron donor and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron acceptor respectively. The device performance was subsequently measured and compared.
关键词： Metal oxide,Sol-gel,Buffer layers,Spin coating,Solar cell,Organic
更新于2025-09-23 15:19:57
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Optical properties of the perovskite films deposited on meso-porous TiO2 by one step and hot casting techniques
摘要： In this work, CH3NH3PbI3 is coated on meso-porous TiO2 films via one step method (OSM) and hot casting technique (HCT). The optical properties of the solution-processed organic inorganic halide perovskite layers deposited on meso-structured TiO2 scaffolds are investigated using UV–Vis reflectance and transmittance spectroscopies at the wavelength range of 400–900 nm. Optical parameters including refractive index, extinction coefficient, real and imaginary parts of the dielectric constants, optical conductivity and direct and indirect optical band gaps are calculated and compared for the perovskite films created by above mentioned methods. Optical band gaps are determined from the absorption coefficient values using Tauc's power law. The obtained values of direct band gap for two perovskite films are close to each other (1.56 and 1.58 eV for perovskite layer deposited by OSM and HCT respectively). For both prepared films, the difference between direct and indirect band gaps is 60 meV which is in very good agreement with that reported in literature. In addition to the difference between the perovskite morphology, the optical absorption of perovskite layers created by the HCT is less than that of layers prepared by OSM and therefore the amount of generated photo current is less. This is the main reason that causes the efficiency of perovskite solar cells prepared by HCT (3.0 %) is ~38% less than that of cells created by OSM (4.15 %).
关键词： Spin Coating,one step,Hot casting,Optical properties,Perovskite solar cell
更新于2025-09-23 15:19:57
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Electrical characterization of two analogous Schottky contacts produced from <i>N</i> -substituted 1,8-naphthalimide
摘要： The aim of this study was to analyze the interface states (Nss) in pure Al//p-Si/Al, Al/N-F Nft/p-Si/Al and Al/N-T Nft/p-Si/Al Schottky barrier diodes (SBDs). N-Substituted 1,8-naphthalimide thin films were deposited on a p-Si substrate by spin coating and annealed at B200 1C for 60 s under an air atmosphere. Al contacts were obtained via reactive magnetron sputtering. The current voltage (I–V) characteristics of the SBDs were measured at room temperature. From the I–V characteristics, the SBDs ideality factor (n) and zero-bias barrier height values (Fb) of 1.27, 1.00, and 1.05 and 0.66 eV, 0.70 eV, and 0.64 eV were observed for the Al//p-Si/Al, Al/N-F Nft/p-Si/Al and Al/N-T Nft/p-Si/Al Schottky barrier diodes, respectively. The interface state density distribution profile (Nss) as a function of (Ess–Ev) was extracted from the forward-bias I–V measurements by considering the effective barrier height and (Fe) and series resistance (Rs) of the Schottky diode. The obtained Nss plot tendency showed that the existence of interface states has no significant effect on the rectifying and capacitance characteristics. The Nss values with the 1,8-naphthalimide layer were lower than that without it. This shows that naphthalimide exhibits a strong contribution by blocking the unwanted states and some traps in the conduction mechanism, which may cause possible cracks or deep paths for carriers to travel along the junction.
关键词： magnetron sputtering,interface states,Schottky barrier diodes,spin coating,1,8-naphthalimide
更新于2025-09-23 15:19:57