Morphology Of Thin Films Research Articles

Phase tailoring of silver oxide thin films for improved antimicrobial activity

This paper reports on routes to control the silver oxide phase and morphology in thin films to enhance their antimicrobial efficacy. The Ag:O atomic ratio was tailored during the pulsed laser deposition process by adjusting the O2 environment, and thus, a wide range of silver oxide phases ranging from Ag to AgxO was achieved. Simultaneously, the morphology was controlled from island-like (Volmer–Weber) formations to nanoparticle arrays, ultimately culminating in cauliflower-like dendrite structures. Through this synergistic approach, enhancing the oxygen content while expanding the active surface area yielded optimal enhancement of the antimicrobial properties. Remarkably, films deposited at elevated O2 pressures exhibited heightened inhibitory effects against bacterial biofilms, with films featuring nanoparticle morphology demonstrating notable antistaphylococcal efficacy.

Enhancement of copper nanoparticle yield in magnetron sputter inert gas condensation by applying substrate bias voltage and its influence on thin film morphology

Large-scale synthesis of high-purity nanoparticles is an intense topic of scientific research, with magnetron sputter inert gas condensation recognized as a promising, environmentally friendly technique avoiding wet chemical processes. This study explores the deposition of size-selected nanoparticles under varied substrate bias voltages and reports on a consequent increase in deposition rates up to 32 %. These alterations in substrate bias voltage induce a progressive change in the morphology of the resulting nanoparticle thin films, attributable to the increased kinetic energy of the nanoparticles. Comprehensive characterization via quadrupole mass spectroscopy of the nanoparticle flux, scanning electron microscopy, X-ray photoelectron spectroscopy, and low-energy ion scattering spectroscopy of the deposited nanoparticles corroborates the enhanced nanoparticle yield associated with increased substrate bias voltage. These findings signify a methodological advancement, enhancing the efficiency of magnetron sputter inert gas condensation and moving the technology a step further towards feasible industrial production.

High quality perovskite thin films synthesized by low-temperature supercritical carbon dioxide annealing method

Thermal annealing is a conventional method used to eliminate residual solvents in perovskite films, reducing internal and interfacial defects. However, due to the high saturation vapor pressure of the residual solvent dimethyl sulfoxide, it is difficult to quickly remove the residual solvent at low temperatures. In this paper, the high permeability and diffusion of supercritical CO2 (ScCO2) were used to quickly remove the residual solvent of film at low temperatures. The effects of ScCO2 annealing on the surface morphology, residual solvents, internal and interfacial defects of perovskite thin films were investigated. The experimental results indicate that ScCO2 annealing significantly improves the removal efficiency of residual solvents compared to low-temperature annealing, effectively minimizing internal and interfacial defects. Additionally, the interaction energy of CO2 with the perovskite crystal plane reduces the surface energy of the crystal, resulting in a significant increase in the average grain size of the crystal by about 91.2%. Notably, the average crystal size of the film prepared by chlorobenzene as an antisolvent increased from 209.35 nm to 704.57 nm. The high penetration of ScCO2 also promoted uniform crystal growth, thereby reducing crystal structure deformation and defects. The carrier lifetime of perovskite thin films after ScCO2 annealing increased by over 58.8% on average.

Dimeric Acceptors Using Different Central Linkers to Manipulate Electronic and Morphological Properties

AbstractDimerized acceptors show promise in combining the high performance of small‐molecule non‐fullerene acceptors (NFAs) with the excellent stability of polymer acceptors. The central linking units that connect two acceptor molecules together have a profound impact on dimeric acceptor properties and structure‐performance relationships in blended thin films. It is seen that different linkers significantly affect the electronic properties and morphology in blended thin film. The electron‐donating linker elevates the absorption coefficient, affords a lower bandgap, and reduces energy loss, and thus better photovoltaic device performance. Better fibrillar morphology can be obtained. The best material DY‐EDOT‐based device shows a power conversion efficiency (PCE) of 18.21%, an open‐circuit voltage (Voc) of 0.924 V, a short‐circuit current density (Jsc) of 25.20 mA cm−2, a fill factor (FF) of 78.19%, which is among the highest value for dimerized acceptors. This study reveals the fundamental importance of linker units in determining the dimerized acceptor properties and provides useful strategies for developing oligomeric and polymeric acceptors, which is critical in simultaneously improving the performance and stability of organic solar cells (OSCs).

Mechanical Deformation Effects on Flexible Thin Film Transistors: A Comparison Between 6,13‐Bis(Triisopropylsilylethynyl)Pentacene and N,N′‐Bis‐(2‐Ethylhexyl)‐1,7‐Dicyanoperylene‐3,4:9,10‐bis(Dicarboximide) Derivatives

AbstractIn this work, the investigation of the surface strain‐induced electrical changes in two commonly employed solution‐processable organic semiconductors, i.e., 6,13‐bis(triisopropylsilylethynyl)pentacene (TIPS‐Pentacene) and N,N′‐bis‐(2‐ethylhexyl)−1,7‐dicyanoperylene‐3,4:9,10‐bis(dicarboximide) (N1400), is reported. A detailed electromechanical characterization of two sets of flexible organic field‐effect transistors is performed, clearly demonstrating that both systems are affected by mechanical deformation in terms of electrical performance. However, the N1400 system shows a much more stable and reproducible response, even after continuous mechanical stress. XRD and AFM analysis demonstrate that such difference is mainly related to the changes induced on the two thin film morphology by the applied deformations.

Impact of Cu doping on morphology, structural and optical characteristics of SnO2 thin films prepared by spray pyrolysis

Impact of Cu doping on morphology, structural and optical characteristics of SnO2 thin films prepared by spray pyrolysis

Effect of discharge pulse frequency on the microstructure and field-emission performance of CNX films deposited by pulse cathode arc evaporation

CNX thin films were prepared by a pulse cathode arc technique using nitrogen as a dopant at different frequencies. Microstructure, compositions, and morphology of CNX thin films were investigated in the dependence of discharge pulse frequency by Raman spectroscopy, x-ray photoelectric spectroscopy (XPS), atomic force microscopy, scanning electron microscopy, UV–vis spectrophotometry, Hall measurements, and field-emission test. The results of Raman and XPS showed that the Csp2 cluster size of CNX films decreases and then increases and decreases with discharge pulse frequency increasing. The Csp2 cluster size of the films prepared at 9 Hz was the largest. The size of Csp3 content increases for the CNX films at the high discharge pulse frequency. The variation of C–N bonding content with frequency in CNX films is similar to that of Csp2. CNX thin films prepared at a frequency of 9 Hz were improved field-emission properties corresponding to the variation of microstructure parameters (the size and ordering of Csp2 clusters) and compositions (C–N bonds). The excellent field-emission properties, such as a low turn-on electric field of 2.1 V/μm and a high field-emission current density of 517.34 μA/cm2, were obtained.

SEM and TEM Image Analysis for Morphology and Phase Transition of CZTS, Sb2Se3 and Perovskite Thin Films under Thermal Stress

SEM and TEM Image Analysis for Morphology and Phase Transition of CZTS, Sb2Se3 and Perovskite Thin Films under Thermal Stress

Comparative study of zirconium-zinc oxide thin films on ceramic and glass substrates: Structural, optical, and photocatalytic properties

This study investigates the structural, optical, and photocatalytic properties of zirconium-doped zinc oxide (Zr) thin films deposited on ceramic and glass substrates. X-ray diffraction (XRD) analysis revealed that all samples exhibited a polycrystalline wurtzite structure, with grain sizes ranging from 25 to 43 nm for ceramic substrates and 19 to 32 nm for glass substrates. UV–visible absorbance measurements indicated that Zr films absorbed visible light around 410 nm, with the band gap widening to 2.93 eV on ceramic substrates. Scanning electron microscopy (SEM) showed that Zr doping significantly affected the morphology of thin films, resulting in rougher surfaces and larger grains on ceramic substrates. Photocatalytic tests demonstrated that the 5 wt% Zr on DD1Z ceramic achieved a degradation efficiency of 61.44 % for orange II dye after 5 h of UV irradiation. In contrast, Zr on ceramic substrates achieved only 18.56 %, and the bare DD1Z substrate reached just 4.02 %. These findings highlight the superior photocatalytic performance of Zr on ceramic substrates, indicating their potential for advanced water purification technologies. The mechanism of photolysis was investigated using hole/radical scavengers, revealing that Zr-ZnO networks enhance the adsorption of hydroxyl ions on the surface. This acts as a trap site, reducing hole/electron pair recombination and thus increasing activity and photodegradation efficiency.

Early Strength and Microscopic Mechanisms of Alkali-Metal Hydroxide-Activated Tungsten Tailings

The excellent mechanical properties of alkaline-activated tailings are essential for their increased use in building materials. While numerous studies have been conducted on activated tailings, the strength of alkaline-activated tungsten slag has not been extensively explored due to the low reactivity of silicon and aluminum in these tailings. This research delves into the early unconfined compressive strength of tungsten tailings activated by two alkali solutions (NaOH and KOH) at three different alkali concentrations (mass ratio of alkali to tungsten tailings), cured at 80 °C over periods of one day, three days, and seven days. The study finds significant improvements in the stability of tungsten tailings when forming (C, N)-A-S-H or (C, K)-A-S-H gels with both alkalis. Scanning Electron Microscope (SEM) results show that the morphology of the (C, N)-A-S-H gels transitions from membranous to flocculated and then to a three-dimensional network as the NaOH content and curing time increase. Conversely, the (C, K)-A-S-H gels primarily exhibit thin-film morphology with some three-dimensional network structures. The presence of flocculation and three-dimensional mesh in the gels fosters the formation of a robust skeletal structure, enhancing the strength of the samples. Furthermore, specimens treated with NaOH solution exhibit a higher gel content compared to those treated with KOH solution. These factors contribute to the superior efficacy of sodium hydroxide in enhancing the strength of tungsten tailings compared to potassium hydroxide. X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) results identify the formation of new phases such as pirssonite, buetschliite, potassium bicarbonate, and potassium carbonate. The first new phase results from the carbonization of excess NaOH solution, while the latter phases arise from the carbonization of excess KOH solution. These carbonization processes negatively impact the strength of the materials.

High-Performance Vis–NIR Photodetectors Based on Two-Dimensional Bi2Te3 Thin Film and Applications

Two-dimensional materials have excellent optoelectronic properties and have great significance in the field of photodetectors. We have prepared a thin film photodetector based on bismuth telluride (Bi2Te3) topological insulator using dual-temperature-zone vapor deposition technology. Due to the high-quality lattice structure of Bi2Te3 and the uniform and dense surface morphology of the Bi2Te3 thin film, the device exhibits excellent photoelectric response and Vis–NIR spectral range. Under 405 nm illumination, the responsivity is 5.6 mA/W, the specific detectivity is 1.22 × 107 Jones, and the response time is 262/328 ms. We designed a photodetector single-point scanning imaging system and successfully achieved high-resolution imaging at a wavelength of 532 nm. This work provides guidance for the application of two-dimensional materials, especially Bi2Te3, in the fields of photodetectors and imaging.

Impact of in situ heating on the structure, morphology, and electrical and optical properties of RF-sputtered NiO thin films

Impact of <i>in situ</i> heating on the structure, morphology, and electrical and optical properties of RF-sputtered NiO thin films

Molecular engineering of oxadiazole-based small organic-functional molecules as hole transporting materials for dopant-free perovskite solar cells

The present investigation concerns the synthesis and characterization of new hole-transporting materials (HTMs) for dopant free perovskite solar cells (PSCs). In this work, emphasis is placed on three new HTMs, specifically materials P-H, P-OMe, and P-CN, whose center-core is 2,2'-(4,8-bis(octyloxy)benzo[1,2-b:4,5-b']dithiophene (OBDT) and combined with two donor units of substituted triphenylamine as at both ends along with oxadiazole acceptor units in between donor and OBDT. The fabrication of perovskite solar cell devices using new HTMs and compared the power conversion performance with the standard spiro-OMeTAD HTM. Several spectroscopic techniques were utilized to characterize the properties of the new HTMs, such as FESEM analysis of thin-film morphologies, time-dependent photoluminescence (PL) spectra, and mobility measurements. The HTMs P-OMe established a compressed and steady protective layer on the perovskite layer. This layer contributed to the development of open-circuit voltage (VOC) and short-circuit current density (JSC), both of which are crucial for accomplishing high power conversion efficiency (PCE) in PSCs. The PSC device integrating the P-OMe HTM displayed a superior PCE of 21.14 % over an active area of 0.22 cm2. This activity was related to the standard device that utilized the standard Spiro-OMeTAD HTM, which accomplished a PCE of 17.46 %. The improved devices with the P-OMe HTM continued about 90 % of their initial PCE throughout maximum power point tracking (MPPT) for 90 days. Furthermore, these devices engaged in their activity over a further 2160 h under various temperature settings (25 °C and 35 °C), probably because of the hydrophobic property of the HTM.

Thin Film Formation Based on a Nanoporous Metal-Organic Framework by Layer-By-Layer Deposition.

Understanding the structure of thin films is essential for successful applications of metal-organic frameworks (MOFs), such as low k-dielectrics in electronic devices. This study focuses on the thin film formation of the 3D nanoporous MOF Cu2(bdc)2(dabco). The thin films are prepared by a layer-by-layer technique with varying deposition cycles (1 to 50). Thin film morphologies and crystallographic properties were investigated using atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and grazing-incidence X-ray diffraction (GIXD). AFM revealed an island growth (Volmer-Weber) with plate-like shaped islands. FTIR and GIXD revealed that Cu2(bdc)2(dabco) crystals form already during the first preparation cycle. The heights of the islands do not increase linearly with the number of deposition cycles, suggesting multiple growth stages. X-ray diffraction pole figures uncover a uniplanar texture of the Cu2(bdc)2(dabco) crystals, together with randomly oriented crystallites. The fraction of uniplanar oriented crystals increases with each deposition cycle, reaching a maximum of 75% at ten deposition cycles, simultaneously achieving complete substrate coverage. However, already at five cycles, an additional phase of randomly oriented copper-terephthalate (Cu2(bdc)) crystals appeared; this phase reaches a fraction of 22% at the largest film thickness (50 cycles). In summary, a detailed understanding of the thin film formation of an archetypal layer-pillar MOF is presented, elucidating how films grow in terms of their morphology and crystalline properties. Samples prepared by ten cycles show complete coverage of the substrate together with the highest degree of preferred crystal orientation. These results establish a deepened understanding of critical parameters for MOF thin film applications, such as complete substrate coverage and definition of the nanopores relative to the substrate surface.

Effect of substrate temperature on the performance of Sb2Se3 thin film solar cells fabricated by chemical-molecular beam deposition method

Antimony triselenide (Sb2Se3) stands as a promising candidate for photovoltaic (PV) applications due to its favorable material- and optoelectronic properties. However, the realization of further advancements in device efficiency is hindered by the substantial deficit in open-circuit voltage (VOC) attributed to the presence of multiple defect states and detrimental recombination losses.In this work, solar cells based on Sb2Se3 absorber layers deposited by chemical-molecular beam deposition method at substrate temperatures of 400 °C, 450 °C, and 500 °C. Due to the precise control of the Sb/Se ratio, Sb2Se3 thin films with stoichiometric composition were obtained, which was confirmed by energy-dispersive X-ray spectroscopy. The effect of substrate temperature on the morphology and electrical properties of Sb2Se3 thin-films were characterized by scanning electron microscopy and hot probe method. The PV performance of Mo/Sb2Se3/ZnCdS/CdS/ZnO/ITO/Au devices were investigated by current-voltage characteristics, and external quantum efficiency. The conductivity values tend to increase from 1.2 × 10–6 to 4.6 × 10–4 (Ω cm)-1 as the substrate temperature increased. Whereas, the trap-state density was determined between 7.3 × 1013 – 1.7 × 1014 cm-3 in the absorber layer by the space charge limited current method. Ultimatety, it has been shown that defect densities in Sb2Se3 films can be suppressed to some extent by optimizing the substrate temperature. Best solar cell performance of 5.36%, resulting from VOC of 476 mV, short-circuit current densit of 22.97 mA/cm−2, and fill factor of 49% at the substrate temperature of 450 °C.

Comparative Study of Zinc Sulfide Thin Films Fabricated by Spin Coating and Rf Magnetron Sputtering as a Buffer Layer for 2nd Generation Photovoltaics

To meet the requirements of second generation photovoltaics, spin coating and RF magnetron sputtering techniques have been utilized to fabricate zinc sulfide thin films for buffer layer optimization. During fabrication process, substrate temperatures for spin coating and RF magnetron sputtering processes are kept at room temperature and at 200 oC, respectively. Thin films are annealed at 500oC for 1 hour in an inert environment to acquire crystallinity and uniform surface morphology. XRD analysis reveals that thin films fabricated by spin coating and RF magnetron sputtering exhibit wurtzite and zinc blende crystal structures, respectively. SEM shows that the surface morphology of thin films fabricated by both techniques is uniform and homogeneous without voids and cracks. EDS results indicate that thin films fabricated via spin coating have equal stoichiometric ratio of zinc to sulfur (1:1). Whereas, an unequal stoichiometric ratio of zinc to sulfur is detected in RF magnetron sputtered thin films. According to optical studies, spin coated zinc sulfide thin films have 67% transmission with an energy band gap of 3.62 eV. While, RF magnetron sputtered thin films have 76% transmission with a wide energy band gap of 3.70 eV. Electrical properties depict that thin films fabricated by RF magnetron sputtering have higher carrier concentration, lower resistivity and higher conductivity than spin coated thin films. In comparison, RF magnetron sputtered zinc sulfide thin films exhibit best structural and optoelectronic properties for buffer layer in second generation solar cells.

Insulator-donor electron wavefunction coupling in pseudo-bilayer organic solar cells achieving a certificated efficiency of 19.18%

Abstract The incorporation of polymeric insulators has led to notable achievements in the field of organic semiconductors. By altering the blending concentration, polymeric insulators exhibit extensive capabilities in regulating molecular configuration, film crystallinity, and mitigation of defect states. However, current research suggests that the improvement in such physical properties is primarily attributed to the enhancement of thin film morphology, an outcome that seems to be an inevitable consequence of incorporating insulators. Herein, we report a general and completely new effect of polymeric insulators in organic semiconductors: the insulator-donor electron wavefunction coupling effect. Such insulators can couple with donor polymers to reduce the energy barrier level and facilitate the intramolecular electron transport. Besides the morphological effects, we observed that this coupling effect is another mechanism that can significantly enhance the electron mobility (up to 100 times) through the incorporation of polymeric insulators in a series of donor systems. With this effect, we proposed a polymeric insulator blending approach to fabricate state-of-the-art pseudo-bilayer organic solar cells, and the PM6/L8-BO device exhibits a high efficiency of 19.50% (certificated 19.18%) with the improved interfacial electron transport property. This work not only offers a novel perspective on the quantum effect of polymeric insulators in organic semiconductors, but also presents a simple yet effective method for enhancing the performance of organic solar cells.

Influence of sulfurization process in tin sulfide and sulfur mixed vapors on the morphology of Cu2SnS3 thin films

Abstract Cu2SnS3 (CTS) is expected to be an absorber material for next-generation solar cells because it is composed of nontoxic, low-cost elements and has an absorption coefficient of &gt;104 cm−1. In this study, the effects of sulfurization in tin sulfide (Sn x S y ) and S mixed vapors on various properties of CTS were investigated by using a 3-zone tube furnace to suppress carrier recombination at the grain boundaries and control the composition of the CTS. The CTS deposited via sulfurization in S vapor only (1-zone CTS) contained different monoclinic and tetragonal CTS structures. The grain size of the CTS thin films deposited via sulfurization in Sn x S y and S mixed vapors was not increased. On the other hand, crystal structure analysis revealed that the CTS had grown to single-phase monoclinic CTS. The results suggest that precipitation in Sn x S y and S mixed vapors contributes to the growth of monoclinic CTS with suitable power-generation characteristics. This finding is important for realizing high-efficiency CTS-based solar cells.

Effect of Sputtering Conditions on the Microstructure and Optical Properties of SnO2 Thin Films

The transmittance and surface smoothness of SnO2 thin films directly affect the performance and use of optical devices, while sputtering conditions determine the morphology and optical properties of SnO2 thin films. In order to study the effect of sputtering conditions on the morphology and optical properties of SnO2 films, the FJL-560 Magnetron sputtering system was used to prepare SnO2 films at different sputtering temperatures on silicon and glass substrates. The results show that the sputtering temperature has a significant impact on the crystallinity of SnO2 thin films. Silicon-based SnO2 thin films can achieve the optimal crystallization state at room temperature, while glass-based SnO2 thin films have an optimal crystallization temperature of 250 °C. The higher the sputtering temperature, the larger the grain size of the thin films; The substrate and temperature did not have a significant impact on the Raman spectrum peak position and waveform of SnO2 thin films, while the Raman spectrum peak intensity of glass substrate was significantly stronger than that of silicon substrate; The average transmittance of SnO2 thin film can reach around 80%, and as the sputtering temperature increases, the transmittance of the film decreases.

Imaging Locally Inhomogeneous Properties of Metal Halide Perovskites.

Metal halide perovskites (MHPs) are a perfect example of state-of-the-art photovoltaic materials whose compositional and structural diversity,coupled with utilization of low-temperature processing, can undesirably result in spatially inhomogeneous properties that locally vary within the material. This complexity of MHPs requires sensitive imaging characterization methods at the microscopic level to gauge the impact of such inhomogeneities on device performance and to formulate mitigation strategies. This review consolidates properties of MHPs that are susceptible to local variations and highlights appropriate imaging techniques that can be employed to map them. Inhomogeneities in morphology, emission, electrical response, and chemical composition of MHP thin films are specifically considered, and possible microscopic techniques for their visualization are reviewed. For each type of microscopy, a short discussion about spatial resolution, sample requirements, advantages, and limitations is provided, thus leaving the reader with a guide of available imaging characterization tools to evaluate inhomogeneities of their MHPs.