Commercial Fluorine-doped Tin Oxide Research Articles

Effect of transparent conductive layers on the functionality of liquid crystal devices: Comparison of AZO, FTO and ITO

The integration of highly transparent and highly conductive layers plays a crucial role in the advancement of various next-generation optoelectronic technologies. Here, we demonstrate a comparison of optical, electrical and wettability properties of Aluminum-doped Zinc Oxide (AZO) deposited by Atomic Layer Deposition Technique (ALD) with commercially available Fluorine-doped Tin Oxide (FTO) and Indium-doped Tin Oxide (ITO) Transparent Conductive Oxide (TCO) layers. Their impact on the electro-optical modulation behavior when applied in Liquid Crystal (LC) device assemblies are compared and discussed. The AZO layers performance prove that are fully competitive to the commercial FTO and ITO layers and verify the high demand for the next generation indium tin oxide (ITO)-free technology.

Amorphous transparent conducting oxide for van-der Waals semiconductor bifacial transparent photovoltaics

Building integrated photovoltaic systems have necessitated the development of transparent photovoltaics (TPV). Transparent conducting oxides (TCO) play a vital role in charge carrier transport in TPVs. Their high transparency, electrical conductivity, and tunable work function make them imperative for TPV applications. Here in this work, we develop a room-temperature grown amorphous-InZnO (a-IZO) thin film for the bottom electrode for TPV. The a-IZO film has demonstrated a high average visible transmittance of 84 % over commercial F:SnO2 (FTO) substrate. A TPV with wide band gap oxide (n-Ga2O3) and a very thin layer of van der Waals material (p-SnS) was fabricated over the a-IZO thin film and commercial FTO substrate for better comparison. A significant enhancement in the current density, open-circuit voltage, and fill factor was recorded. The device with a-IZO electrode showed a bifacial power production feature with a power conversion efficiency of 3.9 % in contrast to FTO electrode-based TPV with 1.5 %. The a-IZO-based TPV also showed a good UV–vis photodetection ability with the highest responsivity of 93 mA/W and the fastest response time of 400 μs. This work suggests that enhanced photovoltaic and photodetection performance is possible using an optimum electrode design.

Fabrication and processing of bacterial cellulose/silver nanowire composites as transparent, conductive, and flexible films for optoelectronic applications

AbstractThis work reports on the engineering and fabrication of transparent, conductive, and flexible films made as a composite of bacterial cellulose microfibers (BMF), a polymer (either PVA or PEO), and silver nanowires (AgNWs) as viable and cost‐effective replacements to commercial indium‐tin oxide (ITO) and fluorine‐doped tin oxide (FTO) transparent conductors. The studies conducted indicate that the optical and mechanical properties of BMF‐polymer substrates are tuneable by varying the ratio of BMF to polymer. An optimized ratio of 70:30 of BMF to polymer was established for BMF‐PVA and BMF‐PEO composites. The optimized composite films were coated with varying amounts of AgNWs. As the AgNW loading increased, the deposition density of AgNW networks increased, while the sheet resistance and optical transmittance decreased. The optimum AgNW loading was determined at 0.20 mg for both composite films. The BMF‐PVA‐AgNW film displayed transmittance between 81% and 71% and an average resistivity of 9.462 ± 0.588 Ω/sq while the BMF‐PEO‐AgNW films showed transmittance between 73% and 65% and an average resistivity of 9.388 ± 0.1.375 Ω/sq. These properties compared well to that of commercial ITO and FTO glass substrates. The findings promote cellulose‐based composites as low‐cost, lightweight, and durable substrates for optoelectronic applications.

Electrochemical stability and corrosion mechanism of fluorine-doped tin oxide film under cathodic polarization in near neutral electrolyte

Commercial fluorine-doped tin oxide (FTO) coated glass slides were subjected to different cathodic potentials for 15 min in 0.2 M Na2SO4 of pH 6.42 to study their electrochemical stability. Results showed that FTO could maintain its electrochemical stability until -1200 mV. However, when it was cathodically polarized from -1600 mV to more negative potentials, band structure positions started to shift upwards, the electrolyte became more acidic and a porous structure appeared on the FTO surface. At -2000 mV, a layer of metallic Sn was seen deposited on the FTO surface, verified by X-ray diffraction and scanning electron microscopy – energy dispersive X-ray spectroscopy. During the cathodic corrosion in near neutral electrolyte, the reduction of SnO2 to Sn involves water oxidation as well as hydrogen evolution reaction.

(Invited) Ceramic Nano-Heterostructures By Materials Design: Platforms for Sensing Applications – Opportunities and Challengess

This talk summarizes R&D efforts in the author’s laboratory on the fabrication of oxide nano-heterostructures, exploiting intrinsic material properties, that are highly scalable and do not require use of lithography. One such process creates crystallographically oriented nanofiber arrays of single crystal TiO2 in H2/N2 environment. H2/N2 heat treatment was also used to grow nanofibers on polycrystalline SnO2, showing directional growth on grains with crystal facets. We have also developed a process to create nanofibers of TiO2 on Ti metal/alloys via oxidation under a limited supply of oxygen. In another process, SnO2 nanowires grown from commercial FTO slides using the vapor-liquid-solid (VLS) method were placed in a microwave-assisted hydrothermal chamber where TiO2 nanorods nucleated radially from the SnO2 nanowire cores. We developed yet another interesting nano-structure (nanoislands and/or nanobars) during thermal annealing of an oxide (GDC) on top of another oxide (YSZ) substrate that self-assembles along the softest elastic direction of the substrate. What is common about these structures is that they are fabricated without the use of lithographic techniques and involves simple processes such as gas-phase reactions and stress-driven processes. These nano-heterostructures can be used as platforms for chemical sensing, catalysis, photocatalysis, photovoltaics and biomedical applications. Sensing application presents opportunities and challenges that are presented including an Open access Database Of Resistive type gas Sensors (ODORS) that has been developed and can be used to select suitable sensing materials.

Role of lithium intercalation in fluorine-doped tin oxide thin films: Ab initio calculations and experiment.

Using a combination of experimental techniques and density functional theory (DFT) calculations, the influence of lithium insertion on the electronic and electrochemical properties of fluorine-doped SnO2 (FTO) is assessed. For this purpose, we investigate the electrochromic behavior of a commercial FTO electrode embedded in a solution of lithium perclorate (LiClO4). The electrochromic properties are evaluated by UV-vis spectroscopy, cyclic voltammetry, and chronoamperometry. These tests show that FTO exhibits electrochromism with a respectable coloration efficiency (η = 47.9 cm2/C at 637nm). DFT study indicates that lithium remains ionized in the lattice, raising the Fermi level about 0.7eV deep into the conduction band. X-ray photoelectron spectroscopy (XPS) is used to study chemical bonding and oxidation states. XPS analysis of the Sn 3d core levels reveals that lithium insertion in FTO induces a shift of 350meV in the Sn 3d states, suggesting that lithium is incorporated into the SnO2 lattice.

Impact of Humidity and Temperature on the Stability of the Optical Properties and Structure of MAPbI3, MA0.7FA0.3PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 Perovskite Thin Films.

In situ real-time spectroscopic ellipsometry (RTSE) measurements have been conducted on MAPbI3, MA0.7FA0.3PbI3, and (FAPbI3)0.95(MAPbBr3)0.05 perovskite thin films when exposed to different levels of relative humidity at given temperatures over time. Analysis of RTSE measurements track changes in the complex dielectric function spectra and structure, which indicate variations in stability influenced by the underlying material, preparation method, and perovskite composition. MAPbI3 and MA0.7FA0.3PbI3 films deposited on commercial fluorine-doped tin oxide coated glass are more stable than corresponding films deposited on soda lime glass directly. (FAPbI3)0.95(MAPbBr3)0.05 films on soda lime glass showed improved stability over the other compositions regardless of the substrate, and this is attributed to the preparation method as well as the final composition.

Photovoltaic and impedance properties of dye-sensitized solar cell based on nature dye from beetroot

The present study involves fabrication and photovoltaic characterization including impedance properties of dye-sensitized solar cells based on natural dye from beetroot. The electrode of the cell was prepared with commercial Fluorine-doped Tin Oxide glass with 100 μm layer of nanostructured TiO2 whereas, the counter electrode consisted of platinum-coated glass. Fresh juice was extracted from beetroot to use as dye. The dye exhibited high absorption in visible range. Photovoltaic measurements of the solar cell gave a short circuit current density (Jsc) of 130 μA/cm2 and an open-circuit voltage (VOC) of 0.38 V under AM 1.5 illumination intensity. The VOC and Jsc showed linear behavior at higher values of illumination intensities. The conductance-voltage, the capacitance-voltage and the series resistance voltage characteristics of the dye solar cell was measured at frequency range from 5 kHz to 5 MHz to study performance of the dye-sensitized solar cells with natural dyes.

Ultrafast laser direct writing on PVP/FTO/Glass substrates to fabricate Ag mesh transparent conductive films

Ag mesh transparent conductive films (TCFs) were prepared on the commercial FTO/Glass substrate by ultrafast laser direct writing, trying to improve its overall photoelectric performances. The effects of laser scanning speed, laser fluence and Ag mesh height on photoelectric properties of the Ag mesh/FTO TCFs were systematically studied. The results indicated that a small scanning speed or a high laser fluence would cause excessive ablation of the FTO film and result in an increased Ag mesh line width, which was detrimental to the photoelectric properties of the resulting TCF. It was found that the optimal parameters for fabricating Ag mesh/FTO TCFs were a laser scanning speed of 2200 mm/s, a laser fluence of 0.050 J/cm2 and an Ag mesh height of 2500 nm. The as-fabricated TCF possessed the highest figure of merit of 13.03 × 10−2 Ω−1, which was significantly superior to that of the commercial FTO film. Finally, transparent heaters (THs) were prepared respectively based on the optimal Ag mesh/FTO TCF and the FTO/Glass substrate. The Ag mesh/FTO TH exhibited a more excellent heating performance than the FTO TH, further confirming that the overall photoelectric performance of the FTO/Glass substrate had been greatly improved.

Fabrication and thermo stability of the SnO2/Ag/SnO2 tri-layer transparent conductor deposited by magnetic sputtering

Using the magnetic sputtering technique, the SnO2/Ag/SnO2 tri-layer transparent films were fabricated on float glasses successfully. Compared with the commercial FTO (F-doped SnO2) film, the SnO2/Ag/SnO2 tri-layer films have higher visible-light transmittance and better conductivity. The total thickness of the SnO2/Ag/SnO2 films is one third of the commercial FTO film leading to the high visible-light transmittance. The high carrier concentration of the SnO2/Ag/SnO2 films contributes to the tri-layer films’ low resistivity. In addition, to further improve the performance of the SnO2/Ag/SnO2 tri-layer films, samples were annealed under different temperatures. The results illustrate that the lowest sheet resistance (5.92 Ω/sq) and the highest visible-light transmittance (87.0%) were obtained after annealing at 200 °C. Furthermore, the thermal stability of the films could be enhanced by a multi-step annealing process due to the recrystallization effect.

Low-cost green recyclable biomaterial for energy-dependent electrical switching and intact biofilm with antibacterial properties

A highly cost-effective recycled biomaterial extracted from lime peel has been made biocompatible and has been coated on a commercial fluorine-doped tin oxide (FTO) substrate of glass using the spin coating method. Structural, morphologic, electronic, and antibacterial measurements were thoroughly characterized as a green biomaterial thin film using X-rays (XRD), PL, FTIR, Raman, SEM, HRTEM, AFM, I–V, and antibacterial diffusion techniques. The comprehensive analysis of structures of recyclable waste in the form of lime peel extract (LPE) as thin films showed the crystalline cellulose structure that corresponds to the lattice fringe (0.342 nm) exposed by HRTEM. The K+1 interstitial active sites or vacancies in LPE/FTO thin films are confirmed by the PL spectra that show important evidence about conduction mechanisms, and hence facilitates Ag+1 ion migration from the top to the bottom electrode. The AFM investigations revealed the minor surface roughness (169.61 nm) of the LPE/FTO film, which controls the current leakage that is associated with surface defects. The designed memory cell (Ag/LPE/FTO) exhibits stable, reproducible electrical switching under low operational voltage and is equipped with excellent retention over 5 × 103 s. Furthermore, owing to presence of flavonoids and their superior antioxidant nature, lime peel extract powder shows tremendous antimicrobial activity against gram-positive and Gram-negative bacterial strains.

Importance of Bi-O Bonds at the Cs2AgBiBr6 Double-Perovskite/Substrate Interface for Crystal Quality and Photoelectric Performance.

Interface interactions between perovskite materials and substrates are of great significance for the development of high-quality perovskite materials. Herein, we have successfully prepared Cs2AgBiBr6 double-perovskite films via a one-step spin-coating process and demonstrated a novel approach that modifies the surface of substrates with an ultrathin metal oxide (MOx) layer to promote the film quality and photoelectric performance. Characterization results strongly suggest that the improvement is attributed to the Bi-O interfacial interaction at substrate/perovskite interface. Benefiting from this interface interaction, the average grain size of Cs2AgBiBr6 films has remarkably risen up to ∼500 nm, which is nearly four times larger than the one directly deposited on a commercial fluorine-doped tin oxide substrate. Meanwhile, the pin hole surface area ratio has reduced from 2.61 to 0.60%. Furthermore, the corresponding photodetectors (PDs) have been fabricated and the performance has significantly improved owing to the enhanced Cs2AgBiBr6 film quality. The on-off ratio of the optimized PD has a boost of almost 10 times. In addition, the minimum detected irradiation has decreased from 9.7 × 10-8 to 1.9 × 10-9 W cm-2, as well as the maximum detectivity has increased from 3.3 × 1011 to 1.2 × 1013 Jones. These results suggest a feasible method for crystallization improvement of double-perovskite films and indicate promising promotion of photoelectric performance.

Optimized Overall Photoactivity of WO3: Utilization of Incidence Dependence from Photonic Crystal Substrate

AbstractIn this work, conductive PC‐FTO (photonic crystal fluorine doped tin oxide) films are fabricated on commercial FTO substrate. The PC‐FTO films serve as two roles: supplying large nan‐structural loading sites available for the embedded photoactive materials, and also manipulating the incident light to improve the performance of embedded photoactive materials under specific incidence range. Through facile solvothermal approach, WO3 platelets are synthesized directly inside the skeleton of PC‐FTO to form WO3@PC‐FTO photoanode which shows more efficiency utilization of light at certain incidence. These homogeneous coating of WO3 platelets in PC‐FTO film allows the study of photonic crystal impact on the photoactivity as a function of incidence.

Template-Free Nanostructured Fluorine-Doped Tin Oxide Scaffolds for Photoelectrochemical Water Splitting.

The synthesis and characterization of highly stable and conductive F:SnO2 (FTO) nanopyramid arrays are investigated, and their use as scaffolds for water splitting is demonstrated. Current densities during the oxygen evolution reaction with a NiFeOx catalyst at 2 V vs reversible hydrogen electrode were increased 5-fold when substituting commercial FTO (TEC 15) by nanostructured FTO scaffolds. In addition, thin α-Fe2O3 films (∼50 nm thick) were employed as a proof of concept to show the effect of our nanostructured scaffolds during photoelectrochemical water splitting. Double-layer capacitance measurements showed a drastic increase of the relative electrochemically active surface area for the nanostructured samples, in agreement with the observed photocurrent enhancement, whereas UV–vis spectroscopy indicates full absorption of visible light at wavelengths below 600 nm.

Improved FTO/NiOx Interfaces for Inverted Planar Triple-Cation Perovskite Solar Cells

Front electrodes of fluorine-doped tin oxide (FTO) thin films and hole-transporting layers of nickel oxide thin films have been combined to fabricate 1.063 cm2 inverted planar solar cells with cesium-containing triple-cation perovskites as absorber layers. Using atmospheric pressure chemical vapor deposition, FTO layers were obtained with low sheet resistance, decreased root-mean-square roughness, increased transmission, and reduced optical haze values compared with a widely used commercial FTO substrate. Cell performance outperformed the equivalent cells fabricated using the commercial FTO. With full illumination under maximum power point tracking, a stabilized power conversion efficiency of 13.78% was obtained for the champion device.

Effects of thickness on photoelectric properties and perovskite solar cells application of transparent conductive F and Al co-doped ZnO films

ZnO films with excellent photoelectric properties have been realized in this study through low-concentration F-and-Al co-doping, conducted with radio-frequency magnetron sputtering. It has been demonstrated that the valence state of Al gradually changes from the incomplete oxidation state to the oxidation state, though the chemical valence states of F, O, and Zn are stable. The as-prepared films possess good performance with a mobility of ∼41.89 cm2/Vs, resistivity of ∼3.50 × 10−4 Ω cm, and an average transmittance over 90% in the range of 400–1200 nm. Moreover, the crystallinity of the films and effect of Al doping were further improved through post annealing. Consequently, the improved film mobility, carrier concentration, resistivity, and sheet resistance were, respectively, measured as 53.97 cm2/Vs, 5.18 × 1020 cm−3, 2.23 × 10−4 Ω cm, and 2.73 Ω/□. These films are, therefore, superior to the commercial F-doped SnO2 (FTO) and comparable to the Sn-doped In2O3 (ITO) films. High-performance perovskite with a conversion efficiency as high as 16.24% was achieved when the abovementioned optimized film was used as the front electrode. The reference perovskite solar cells that had commercial ITO and FTO as their front electrodes showed lower efficiency of 15.92% and 12.45%, respectively.

Composition and Energy Band–Modified Commercial FTO Substrate for In Situ Formed Highly Efficient Electron Transport Layer in Planar Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs) have received much attention and with them a power conversion efficiency (PCE) of over 22% has been achieved. Electron transport layers (ETLs) based on metal oxide materials play an important role in transferring electrons and reducing back recombination. However, existing fabrication approaches are generally waste too many materials and consume too much energy for commercial application. Here, a brand new plasma preannealing procedure is proposed that can replace the traditional ETL preparation process and alleviate the above‐mentioned problems. A pure SnO2 phase in situ formed on the fluorine‐doped tin oxide (FTO) surface can be obtained at room temperature by only 15 min oxygen plasma assisted reaction without postheating treatment. It enables the precise control of compositions, defects, and energy levels of band at the surface of FTO substrate, resulting in a prominent PCE of 20.39% with excellent stability and reproducibility. This simple and efficient source‐free fabrication technology provides a versatile platform for the manufacture of PSCs in the future.

Electrochromic behavior of fluorine-doped tin oxide film via guided motion of Li ions

Abstract Electrochromic materials, which can change their optical properties in the presence of external electric potential stimuli, have attracted increasing attention due to their promising applications in many fields. In this work, an electrochromic device was assembled using commercial fluorine-doped tin oxide (FTO) film as the active electrochromic material. The light transmittance of FTO was controlled via guided motion of Li ions. The device can be reversibly switched between a deeply colored state and an uncolored state via the inserting/extracting of Li ions in the FTO film. Our results indicate that FTO is a promising electrochromic active material with high color efficiency and low cost.

High-Performance Dye-Sensitized Solar Cells Based on Colloid-Solution Deposition Planarized Fluorine-Doped Tin Oxide Substrates.

The transmittance and conductivity of fluorine-doped tin oxide (FTO) conductive glasses are the critical factors limiting the performance of dye-sensitized solar cells (DSSCs). Here, the transmittance and conductivity of commercial FTO glasses were improved via a colloid-solution deposition planarization (CSDP) process. The process includes two steps. First, the FTO nanocrystal colloid was deposited on the FTO glasses by spin-coating. Secondly, the coated glasses were treated by FTO precursor solution. Compared to the bare FTO glasses, the modified FTO glasses by the CSDP process achieved 4% increase in transmittance (at 550 nm) and 11% decrease in sheet resistance, respectively. In addition, the modified FTO glasses can reduce the aggregation of Pt nanoparticles and improve the electrocatalytic activity of Pt counter electrodes. When the modified FTO glasses were used to assemble DSSCs, the cells got a photoelectric conversion efficiency as high as 9.37%. In contrast, the efficiency of reference cells using bare FTO substrates was about 8.24%.

All‐Solution‐Processed Silver Nanowire Window Electrode‐Based Flexible Perovskite Solar Cells Enabled with Amorphous Metal Oxide Protection

AbstractSilver nanowire (AgNW)‐based transparent electrodes prepared via an all‐solution‐process are proposed as bottom electrodes in flexible perovskite solar cells (PVSCs). To enhance the chemical stability of AgNWs, a pinhole‐free amorphous aluminum doped zinc oxide (a‐AZO) protection layer is deposited on the AgNW network. Compared to its crystalline counterpart (c‐AZO), a‐AZO substantially improves the chemical stability of the AgNW network. For the first time, it is observed that inadequately protected AgNWs can evanesce via diffusion, whereas a‐AZO secures the integrity of AgNWs. When an optimally thick a‐AZO layer is used, the a‐AZO/AgNW/AZO composite electrode exhibits a transmittance of 88.6% at 550 nm and a sheet resistance of 11.86 Ω sq−1, which is comparable to that of commercial fluorine doped tin oxide. The PVSCs fabricated with a configuration of Au/spiro‐OMeTAD/CH3NH3PbI3/ZnO/AZO/AgNW/AZO on rigid and flexible substrates can achieve power conversion efficiencies (PCEs) of 13.93% and 11.23%, respectively. The PVSC with the a‐AZO/AgNW/AZO composite electrode retains 94% of its initial PCE after 400 bending iterations with a bending radius of 12.5 mm. The results clearly demonstrate the potential of AgNWs as bottom electrodes in flexible PVSCs, which can facilitate the commercialization and large‐scale deployment of PVSCs.