Dongmei Dong - Academia.edu (original) (raw)
Papers by Dongmei Dong
Exploring the Dielectric Properties of Lanthanide Oxide Thin Films
Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM), Dec 22, 2023
Real-Time Continuous Monitoring of Fuel Cell Ionomer Degradation with Electrochemical Inline Micro Sensor Arrays
Meeting abstracts, Oct 9, 2022
Multimodal Single-Entity Electrochemical Fluoride Sensor for Fuel Cell Membrane Degradation Diagnostics
ECS Sensors Plus
To the best of our knowledge, very few works have been done for the continuous real-time monitori... more To the best of our knowledge, very few works have been done for the continuous real-time monitoring of Proton Exchange Membrane Fuel Cells (PEMFCs) membrane degradation based on fluoride-specific electrochemical microsensors. PEMFCs are eco-smart energy sources for efficient transportation but experience variable degradation rates that wear the Membrane Electrode Assembly (MEA), a critical component of the fuel cell’s functionality. Current market options lack specific diagnostics and a legitimate indication of when exactly the membrane needs to be replaced. As such, this work focused on manufacturing a sensor for measuring MEA degradation in real-time by selectively monitoring fluoride concentration in effluent water, a signature PEMFCs degradation status, through functionalized LaF3:(Au nanoparticle) thin films (∼60 nm). The sensor’s exceptional specificity/sensitivity has been achieved in real-time at a sub 10 ppb level, optimized through spin-coating deposition and post-annealin...
IntechOpen eBooks, Oct 11, 2023
Despite the natural cycle of climate change being unavoidable and the reality, history has been t... more Despite the natural cycle of climate change being unavoidable and the reality, history has been telling the living the previous civilizations that have overstressed themselves or pushed the consumption of natural resources to the limit, and the consequence soon shows the alert in the climate. It is a critical period of time to change the current in response to climate change by employing environmentally friendly and emission-free energy technologies. The applications of advanced functional thin films ranging from the quantum level to nano and microscale, from inorganic metal oxides to conductive polymers, have been pushing the rapid development of energy-saving technologies and clean and renewable energy production, storage, and conversion in the past decade. This specific chapter focuses on fundamental-and applied-science on various advanced thin films and their applications in reliable renewable energy devices and/or systems, including but not limited to electrochromics, supercapacitors, fuel cells, flow batteries, electrolysis, triboelectricity, etc. Given that much of the work is realized across interfaces, the spotlight is shielded onto the interface of thin films in electrochemistry with different emerging cutting-edge ongoing research examples.
Revealing nanomechanical deformation at the interface and degradation in all-thin-film inorganic electrochromic devices
Nanoscale
Recently, progress in electrochromic (EC) devices has been made in optimizing electrode and devic... more Recently, progress in electrochromic (EC) devices has been made in optimizing electrode and device configurations and performance.
Review—Micro-Fuel Cell Principal Biosensors for Monitoring Transdermal Volatile Organic Compounds in Humans
ECS Sensors Plus
Knowledge of transduction mechanisms in biosensing applications paves the way for ultrasensitive ... more Knowledge of transduction mechanisms in biosensing applications paves the way for ultrasensitive and dynamic detection in living systems. Real-world biosensing applications where ultra-sensitivity and dynamic detection are paramount include monitoring the anesthetic agent concentration during surgery; the slightest variation in concentration can potentially result in a life-threatening overdose or, on the other end of the spectrum, the patient’s awareness during the procedure. We review the benefits and functions of the transcutaneous biosensor device compared with other current technology and discuss the sensor’s capability to accurately measure volatile anesthetic gas concentration in blood using fuel cell technology. We review fundamental concepts of fuel-cell technology for wearable bio-sensing applications. The fuel cell sensor can also continuously monitor other volatile organic compounds making it versatile with numerous potential applications.
Coupling Electro-Chemo- Thermodynamics with Water in Salt (WIS) Electrolyte for Enhanced Pseudocapacitive Charge Storage
ECS Meeting Abstracts
Distinguishing and fundamental understanding of different charge storage mechanisms is critical f... more Distinguishing and fundamental understanding of different charge storage mechanisms is critical for advancing sustainable energy developments. Pseudocapacitive materials combine the Faradaic charge transfer and partial surface-controlled process with the advantages of large energy density and fast response compared to electrical double-layer capacitors and batteries. Electrochromic oxides thin films, as an emerging class of energy storage materials, allow the synchronous visible color change to indicate the energy level. This work involves comprehensive research on the effect of the electrolyte concentration, solvent, and temperature on the charge storage behavior at the interface and the electrochromic properties of amorphous WO3-x films. The Li+ and e- dual insertion/extraction process depends not only on the electrochemical kinetics but also related to the viscosity of the ionic liquid LiCl water-in-salt (WIS) electrolyte varying from room temperature to 70°C. The de-solvation-fr...
(Invited) Development of Fuel Cell-Based Electrochemical Micro Gas Sensor for Monitoring Anesthetic Organic Compounds
ECS Meeting Abstracts
Surgical procedures require administering anesthetic agents in concentrations between 0.5 and 2.0... more Surgical procedures require administering anesthetic agents in concentrations between 0.5 and 2.0% to maintain a patient's sedation. Maintaining the concentration of the anesthetic agents within the specified range is vital in preventing overdose or awareness during procedures. There is an increasing demand for developing an accessible, low-cost, wearable anesthetic sensor to ensure patient and personnel safety. This work focuses on fulfilling the clinical demand by developing a transcutaneous biosensor device that can accurately measure and monitor the concentration of anesthetic agent isoflurane (1-chloro-2,2,2-trifluoromethyl difluoromethyl ether) in the human body at a lower cost per unit to address this unmet need. The approach utilizes the creative form of a micro-fuel cell sensor that is composed of a proton exchange membrane (PEM) sandwiched between two metal electrodes to measure the isoflurane excreted through the subject's skin. At the anode, the isoflurane oxidat...
RSC Advances
Environmental sustainability, safety, cost, and performance are the driving metrics for modern te... more Environmental sustainability, safety, cost, and performance are the driving metrics for modern technological developments.
Pseudocapacitive Charge Storage in Electrochromic Transition-Metal Oxide Thin Films
Journal of The Electrochemical Society
Electrochromic pseudocapacitive transition-metal oxide materials, such as tungsten oxide, which c... more Electrochromic pseudocapacitive transition-metal oxide materials, such as tungsten oxide, which combine fast response, high energy density, and optical effects, can play a significant role as energy storage materials. Here we investigate the electrochemical kinetics of thin films of tungsten oxide, which turn transparent to sky-blue color in the lithiated state due to the reduction of W6+ to W5+. We investigated the charge density, charge transfer, ion diffusion, and interfacial behavior upon Li+ insertion/de-insertion in WO3. The electrochromic thin film’s pseudocapacitive and electrical double layer mechanism was differentiated based on the power-law. Faradaic diffusion-controlled process dominates over the surface capacitive behavior at scan rates below 40 mV s−1. These films exhibit an areal charge density of around 100 mC cm−2 and a capacitance of 80 mF cm−2, superior to most comparable electrochromic materials and supercapacitors. This work combines electrochromics and energy ...
Micro-Fuel Cell Sensor-Based Transcutaneous Anesthesia Monitoring Systems (TAMS)
ECS Meeting Abstracts, 2021
Colorimetric properties and structural evolution of cathodic electrochromic WO3 thin films
Canadian Journal of Chemistry, 2021
Cathodic amorphous tungsten trioxide (WO3) thin films have been deposited by reactive direct curr... more Cathodic amorphous tungsten trioxide (WO3) thin films have been deposited by reactive direct current magnetron sputtering and have been studied for their colorimetric and electrochromic properties. Those studies were carried out under two different potential cycling process: (i) switching mode (the response between coloration and bleaching in increasing potential steps) and (ii) modulation mode (the stepwise modulation to coloration with increasing potential and back to bleaching). Optical measurements, performed as a function of applied potential, showed excellent transmittance contrasts (∼80%) between colored and bleached states. The color stimuli and the changes that take place upon reversible switching or modulation were recorded based on the Commisson International de l’Éclairage (CIE) system. It was found that, under various potentials, significant changes occurred in the hue and saturation for WO3, as exhibited by the CIE 1931 xy chromaticity coordinates. As WO3 was reduced (...
Journal of Materials Chemistry C, 2018
There has been keen interest for years in the research of all-solid-state transmittance-type elec... more There has been keen interest for years in the research of all-solid-state transmittance-type electrochromic (EC) devices due to their various applications especially in “smart windows”. However, limited durability remains a severe issue.
Thin Solid Films, 2018
Thin films of WO3:H (~450 nm) were prepared on indium tin oxide (ITO) coated glass by reactive di... more Thin films of WO3:H (~450 nm) were prepared on indium tin oxide (ITO) coated glass by reactive direct current magnetron sputtering at room temperature. The visible transmittance of the original state, and the X-ray photoelectron spectroscopy analysis of WO3:H films prove that H + ions have been introduced into the structure of WO3. Based on the optimized parameters of WO3:H thin film, the Glass/ITO/WO3:H/Ta2O5/NiOx/ITO electrochromic devices (ECDs) are prepared monolithically by magnetron sputtering. Different applied voltages of 1.0, 2.0 and 3.0 V were applied to the ECD for investigating its influence on the ECD's optical contrast and cycle life. Though the ECD can get a higher contrast about 42% at 550nm under 3.0 V voltage, however, it will be destructed quickly. When the operating voltage is 2.0 V, the ECD has a stable cycle performance with the optical contrast of more than 30%.
Electrochimica Acta, 2018
Great interest has been drawn to the electrochromism demonstrated by inorganic materials, leading... more Great interest has been drawn to the electrochromism demonstrated by inorganic materials, leading to various applications including smart windows and displays. NiO, as a cheap material, shows anodic electrochromism and is highly suitable for device applications in conjunction with W0 3 , but its strong optical absorbanoe has been largely overlooked. Herein, improved electrochromic properties in particular in short wavelengths was achieved by co doping of Mg and Li in NiO:(Ll, Mg) thin films grown using RF sputtering. Secondary Ion Mass Spectroscopy technique in combination with X ray Photoelectron Spectroscopy characterization provides direct evidence of the introduction of Mg as well as Li in the film Whatever the Li and Mg content, X Ray Diffraction and Raman spectroscopy studies only bring out the NiO face centered cubic rock sait structure. Electrochemical cycling shows pronounced anodic electro chromism for NiO:(Ll, Mg) thin films. Inorganic ail solid state monolithic multilayered devices are traditionally composed of a pair of electrodes with NiO and WOJ separated by Li containing electrolyte such as LiTa0 3 or LlNb0 3 sputtered from expensive but low efficient ceramic targets. Based on optimal NiO:(Ll, Mg) films, large switchable electrochromism both in visible (-58%) and ultraviolet band (-50%) is reconciled in electrochromic device Glass/ITO/NiO:(Li, Mg)(ra20sfW0 3 /ITO. The co doping of NiO with Mg and Li is capable of simultaneously widening the gap and avoiding the use of Li containing elec trolyte, through NiO pre lithiation. We believe the new, low cost approach would provide references with respect to practical applications desired for their successful commercial mass production.
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](Nanoscale, Jan 22, 2018
The visualization of the microstructure change and of the depth of lithium transport inside a mon... more The visualization of the microstructure change and of the depth of lithium transport inside a monolithic ElectroChromic Device (ECD) is realized using an innovative combined approach of Focused Ion Beam (FIB), Secondary Ion Mass Spectrometry (SIMS) and Glow Discharge Optical Emission Spectroscopy (GDOES). The electrochemical and optical properties of the all-thin-film inorganic ECD glass/ITO/WO3/LiTaO3/NiO/ITO, deposited by magnetron sputtering, are measured by cycling voltammetry and in situ transmittance analysis up to 11 270 cycles. A significant degradation corresponding to a decrease in the capacity of 71% after 2500 cycles and of 94% after 11 270 cycles is reported. The depth resolved microstructure evolution within the device, investigated by cross-sectional cutting with FIB, points out a progressive densification of the NiO layer upon cycling. The existence of irreversible Li ion trapping in NiO is illustrated through the comparison of the compositional distribution of the d...
Thin Solid Films, 2016
Tungsten doped indium oxide (In 2 O 3 :W, IWO) thin films with IWO micro-grid covered surface wer... more Tungsten doped indium oxide (In 2 O 3 :W, IWO) thin films with IWO micro-grid covered surface were prepared at room temperature using techniques of radio frequency (RF) magnetron sputtering and polystyrene (PS) microsphere template. The composition, crystallization structures, surface morphologies, and optical and electrical properties of the films were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, spectrophotometer from visible to near infrared (NIR) range and Hall effect measurement, respectively. Periodic micro-grid modified surface was obtained to improve light trapping properties. The effects of the PS micro-spheres diameters and the sputtering time on the surface morphology, transmittance in NIR range, diffuse reflection and conductive properties of the IWO films are investigated. Experiments show that surface modification of the IWO film with micro-grid under the optimized condition can improve the conductivity of the films by 15%, and the diffuse reflectance by 150%, with less than 8% decrease of the transmittance in the visible region. The study would be beneficial to the light trapping effect of solar cells using IWO films as transparent electrodes.
Thin Solid Films, 2017
One set of tungsten-doped indium oxide thin films (In 2 O 3 :W, IWO) and another set of tin-doped... more One set of tungsten-doped indium oxide thin films (In 2 O 3 :W, IWO) and another set of tin-doped indium oxide thin films (In 2 O 3 :Sn, ITO) were prepared on glass substrates by radio frequency (RF) reactive magnetron sputtering method. The as-deposited IWO and ITO films have resistivity values at a level of 10 −4 Ω•cm. Average transmittance values of these films are above 85% in visible-light region as well as in near-infrared region. All these films were irradiated by atomic oxygen (AO) with different amount of flux in a ground-based simulation system close to the environment of low Earth orbit. Changes in characteristics including surface morphology, mechanical properties, optical and electrical properties were compared between IWO and ITO films after AO irradiation. The effects of AO irradiation on transparent conductive oxide thin films were analyzed. As a result, AO has influences on ITO and IWO thin films through the way of oxidation and erosion. Both ITO and IWO films possess suitable anti-AO properties. IWO films are more appropriate as AO protective coatings due to their compact microstructure, the coexistence of W 4+ and W 6+ ions in their chemical systems, and incremental WO 3 protective layer under AO oxidation.
Improved performance of co-sputtered Ni–Ti oxide films for all-solid-state electrochromic devices
RSC Advances, 2016
Thin films of Ni–Ti oxide were co-sputtered by reactive direct current magnetron sputtering and t... more Thin films of Ni–Ti oxide were co-sputtered by reactive direct current magnetron sputtering and their structures, morphologies, and compositions were investigated by X-ray diffraction, atomic force microscopy and X-ray photo-electron spectroscopy.
Exploring the Dielectric Properties of Lanthanide Oxide Thin Films
Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM), Dec 22, 2023
Real-Time Continuous Monitoring of Fuel Cell Ionomer Degradation with Electrochemical Inline Micro Sensor Arrays
Meeting abstracts, Oct 9, 2022
Multimodal Single-Entity Electrochemical Fluoride Sensor for Fuel Cell Membrane Degradation Diagnostics
ECS Sensors Plus
To the best of our knowledge, very few works have been done for the continuous real-time monitori... more To the best of our knowledge, very few works have been done for the continuous real-time monitoring of Proton Exchange Membrane Fuel Cells (PEMFCs) membrane degradation based on fluoride-specific electrochemical microsensors. PEMFCs are eco-smart energy sources for efficient transportation but experience variable degradation rates that wear the Membrane Electrode Assembly (MEA), a critical component of the fuel cell’s functionality. Current market options lack specific diagnostics and a legitimate indication of when exactly the membrane needs to be replaced. As such, this work focused on manufacturing a sensor for measuring MEA degradation in real-time by selectively monitoring fluoride concentration in effluent water, a signature PEMFCs degradation status, through functionalized LaF3:(Au nanoparticle) thin films (∼60 nm). The sensor’s exceptional specificity/sensitivity has been achieved in real-time at a sub 10 ppb level, optimized through spin-coating deposition and post-annealin...
IntechOpen eBooks, Oct 11, 2023
Despite the natural cycle of climate change being unavoidable and the reality, history has been t... more Despite the natural cycle of climate change being unavoidable and the reality, history has been telling the living the previous civilizations that have overstressed themselves or pushed the consumption of natural resources to the limit, and the consequence soon shows the alert in the climate. It is a critical period of time to change the current in response to climate change by employing environmentally friendly and emission-free energy technologies. The applications of advanced functional thin films ranging from the quantum level to nano and microscale, from inorganic metal oxides to conductive polymers, have been pushing the rapid development of energy-saving technologies and clean and renewable energy production, storage, and conversion in the past decade. This specific chapter focuses on fundamental-and applied-science on various advanced thin films and their applications in reliable renewable energy devices and/or systems, including but not limited to electrochromics, supercapacitors, fuel cells, flow batteries, electrolysis, triboelectricity, etc. Given that much of the work is realized across interfaces, the spotlight is shielded onto the interface of thin films in electrochemistry with different emerging cutting-edge ongoing research examples.
Revealing nanomechanical deformation at the interface and degradation in all-thin-film inorganic electrochromic devices
Nanoscale
Recently, progress in electrochromic (EC) devices has been made in optimizing electrode and devic... more Recently, progress in electrochromic (EC) devices has been made in optimizing electrode and device configurations and performance.
Review—Micro-Fuel Cell Principal Biosensors for Monitoring Transdermal Volatile Organic Compounds in Humans
ECS Sensors Plus
Knowledge of transduction mechanisms in biosensing applications paves the way for ultrasensitive ... more Knowledge of transduction mechanisms in biosensing applications paves the way for ultrasensitive and dynamic detection in living systems. Real-world biosensing applications where ultra-sensitivity and dynamic detection are paramount include monitoring the anesthetic agent concentration during surgery; the slightest variation in concentration can potentially result in a life-threatening overdose or, on the other end of the spectrum, the patient’s awareness during the procedure. We review the benefits and functions of the transcutaneous biosensor device compared with other current technology and discuss the sensor’s capability to accurately measure volatile anesthetic gas concentration in blood using fuel cell technology. We review fundamental concepts of fuel-cell technology for wearable bio-sensing applications. The fuel cell sensor can also continuously monitor other volatile organic compounds making it versatile with numerous potential applications.
Coupling Electro-Chemo- Thermodynamics with Water in Salt (WIS) Electrolyte for Enhanced Pseudocapacitive Charge Storage
ECS Meeting Abstracts
Distinguishing and fundamental understanding of different charge storage mechanisms is critical f... more Distinguishing and fundamental understanding of different charge storage mechanisms is critical for advancing sustainable energy developments. Pseudocapacitive materials combine the Faradaic charge transfer and partial surface-controlled process with the advantages of large energy density and fast response compared to electrical double-layer capacitors and batteries. Electrochromic oxides thin films, as an emerging class of energy storage materials, allow the synchronous visible color change to indicate the energy level. This work involves comprehensive research on the effect of the electrolyte concentration, solvent, and temperature on the charge storage behavior at the interface and the electrochromic properties of amorphous WO3-x films. The Li+ and e- dual insertion/extraction process depends not only on the electrochemical kinetics but also related to the viscosity of the ionic liquid LiCl water-in-salt (WIS) electrolyte varying from room temperature to 70°C. The de-solvation-fr...
(Invited) Development of Fuel Cell-Based Electrochemical Micro Gas Sensor for Monitoring Anesthetic Organic Compounds
ECS Meeting Abstracts
Surgical procedures require administering anesthetic agents in concentrations between 0.5 and 2.0... more Surgical procedures require administering anesthetic agents in concentrations between 0.5 and 2.0% to maintain a patient's sedation. Maintaining the concentration of the anesthetic agents within the specified range is vital in preventing overdose or awareness during procedures. There is an increasing demand for developing an accessible, low-cost, wearable anesthetic sensor to ensure patient and personnel safety. This work focuses on fulfilling the clinical demand by developing a transcutaneous biosensor device that can accurately measure and monitor the concentration of anesthetic agent isoflurane (1-chloro-2,2,2-trifluoromethyl difluoromethyl ether) in the human body at a lower cost per unit to address this unmet need. The approach utilizes the creative form of a micro-fuel cell sensor that is composed of a proton exchange membrane (PEM) sandwiched between two metal electrodes to measure the isoflurane excreted through the subject's skin. At the anode, the isoflurane oxidat...
RSC Advances
Environmental sustainability, safety, cost, and performance are the driving metrics for modern te... more Environmental sustainability, safety, cost, and performance are the driving metrics for modern technological developments.
Pseudocapacitive Charge Storage in Electrochromic Transition-Metal Oxide Thin Films
Journal of The Electrochemical Society
Electrochromic pseudocapacitive transition-metal oxide materials, such as tungsten oxide, which c... more Electrochromic pseudocapacitive transition-metal oxide materials, such as tungsten oxide, which combine fast response, high energy density, and optical effects, can play a significant role as energy storage materials. Here we investigate the electrochemical kinetics of thin films of tungsten oxide, which turn transparent to sky-blue color in the lithiated state due to the reduction of W6+ to W5+. We investigated the charge density, charge transfer, ion diffusion, and interfacial behavior upon Li+ insertion/de-insertion in WO3. The electrochromic thin film’s pseudocapacitive and electrical double layer mechanism was differentiated based on the power-law. Faradaic diffusion-controlled process dominates over the surface capacitive behavior at scan rates below 40 mV s−1. These films exhibit an areal charge density of around 100 mC cm−2 and a capacitance of 80 mF cm−2, superior to most comparable electrochromic materials and supercapacitors. This work combines electrochromics and energy ...
Micro-Fuel Cell Sensor-Based Transcutaneous Anesthesia Monitoring Systems (TAMS)
ECS Meeting Abstracts, 2021
Colorimetric properties and structural evolution of cathodic electrochromic WO3 thin films
Canadian Journal of Chemistry, 2021
Cathodic amorphous tungsten trioxide (WO3) thin films have been deposited by reactive direct curr... more Cathodic amorphous tungsten trioxide (WO3) thin films have been deposited by reactive direct current magnetron sputtering and have been studied for their colorimetric and electrochromic properties. Those studies were carried out under two different potential cycling process: (i) switching mode (the response between coloration and bleaching in increasing potential steps) and (ii) modulation mode (the stepwise modulation to coloration with increasing potential and back to bleaching). Optical measurements, performed as a function of applied potential, showed excellent transmittance contrasts (∼80%) between colored and bleached states. The color stimuli and the changes that take place upon reversible switching or modulation were recorded based on the Commisson International de l’Éclairage (CIE) system. It was found that, under various potentials, significant changes occurred in the hue and saturation for WO3, as exhibited by the CIE 1931 xy chromaticity coordinates. As WO3 was reduced (...
Journal of Materials Chemistry C, 2018
There has been keen interest for years in the research of all-solid-state transmittance-type elec... more There has been keen interest for years in the research of all-solid-state transmittance-type electrochromic (EC) devices due to their various applications especially in “smart windows”. However, limited durability remains a severe issue.
Thin Solid Films, 2018
Thin films of WO3:H (~450 nm) were prepared on indium tin oxide (ITO) coated glass by reactive di... more Thin films of WO3:H (~450 nm) were prepared on indium tin oxide (ITO) coated glass by reactive direct current magnetron sputtering at room temperature. The visible transmittance of the original state, and the X-ray photoelectron spectroscopy analysis of WO3:H films prove that H + ions have been introduced into the structure of WO3. Based on the optimized parameters of WO3:H thin film, the Glass/ITO/WO3:H/Ta2O5/NiOx/ITO electrochromic devices (ECDs) are prepared monolithically by magnetron sputtering. Different applied voltages of 1.0, 2.0 and 3.0 V were applied to the ECD for investigating its influence on the ECD's optical contrast and cycle life. Though the ECD can get a higher contrast about 42% at 550nm under 3.0 V voltage, however, it will be destructed quickly. When the operating voltage is 2.0 V, the ECD has a stable cycle performance with the optical contrast of more than 30%.
Electrochimica Acta, 2018
Great interest has been drawn to the electrochromism demonstrated by inorganic materials, leading... more Great interest has been drawn to the electrochromism demonstrated by inorganic materials, leading to various applications including smart windows and displays. NiO, as a cheap material, shows anodic electrochromism and is highly suitable for device applications in conjunction with W0 3 , but its strong optical absorbanoe has been largely overlooked. Herein, improved electrochromic properties in particular in short wavelengths was achieved by co doping of Mg and Li in NiO:(Ll, Mg) thin films grown using RF sputtering. Secondary Ion Mass Spectroscopy technique in combination with X ray Photoelectron Spectroscopy characterization provides direct evidence of the introduction of Mg as well as Li in the film Whatever the Li and Mg content, X Ray Diffraction and Raman spectroscopy studies only bring out the NiO face centered cubic rock sait structure. Electrochemical cycling shows pronounced anodic electro chromism for NiO:(Ll, Mg) thin films. Inorganic ail solid state monolithic multilayered devices are traditionally composed of a pair of electrodes with NiO and WOJ separated by Li containing electrolyte such as LiTa0 3 or LlNb0 3 sputtered from expensive but low efficient ceramic targets. Based on optimal NiO:(Ll, Mg) films, large switchable electrochromism both in visible (-58%) and ultraviolet band (-50%) is reconciled in electrochromic device Glass/ITO/NiO:(Li, Mg)(ra20sfW0 3 /ITO. The co doping of NiO with Mg and Li is capable of simultaneously widening the gap and avoiding the use of Li containing elec trolyte, through NiO pre lithiation. We believe the new, low cost approach would provide references with respect to practical applications desired for their successful commercial mass production.
Nanoscale, Jan 22, 2018
The visualization of the microstructure change and of the depth of lithium transport inside a mon... more The visualization of the microstructure change and of the depth of lithium transport inside a monolithic ElectroChromic Device (ECD) is realized using an innovative combined approach of Focused Ion Beam (FIB), Secondary Ion Mass Spectrometry (SIMS) and Glow Discharge Optical Emission Spectroscopy (GDOES). The electrochemical and optical properties of the all-thin-film inorganic ECD glass/ITO/WO3/LiTaO3/NiO/ITO, deposited by magnetron sputtering, are measured by cycling voltammetry and in situ transmittance analysis up to 11 270 cycles. A significant degradation corresponding to a decrease in the capacity of 71% after 2500 cycles and of 94% after 11 270 cycles is reported. The depth resolved microstructure evolution within the device, investigated by cross-sectional cutting with FIB, points out a progressive densification of the NiO layer upon cycling. The existence of irreversible Li ion trapping in NiO is illustrated through the comparison of the compositional distribution of the d...
Thin Solid Films, 2016
Tungsten doped indium oxide (In 2 O 3 :W, IWO) thin films with IWO micro-grid covered surface wer... more Tungsten doped indium oxide (In 2 O 3 :W, IWO) thin films with IWO micro-grid covered surface were prepared at room temperature using techniques of radio frequency (RF) magnetron sputtering and polystyrene (PS) microsphere template. The composition, crystallization structures, surface morphologies, and optical and electrical properties of the films were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, spectrophotometer from visible to near infrared (NIR) range and Hall effect measurement, respectively. Periodic micro-grid modified surface was obtained to improve light trapping properties. The effects of the PS micro-spheres diameters and the sputtering time on the surface morphology, transmittance in NIR range, diffuse reflection and conductive properties of the IWO films are investigated. Experiments show that surface modification of the IWO film with micro-grid under the optimized condition can improve the conductivity of the films by 15%, and the diffuse reflectance by 150%, with less than 8% decrease of the transmittance in the visible region. The study would be beneficial to the light trapping effect of solar cells using IWO films as transparent electrodes.
Thin Solid Films, 2017
One set of tungsten-doped indium oxide thin films (In 2 O 3 :W, IWO) and another set of tin-doped... more One set of tungsten-doped indium oxide thin films (In 2 O 3 :W, IWO) and another set of tin-doped indium oxide thin films (In 2 O 3 :Sn, ITO) were prepared on glass substrates by radio frequency (RF) reactive magnetron sputtering method. The as-deposited IWO and ITO films have resistivity values at a level of 10 −4 Ω•cm. Average transmittance values of these films are above 85% in visible-light region as well as in near-infrared region. All these films were irradiated by atomic oxygen (AO) with different amount of flux in a ground-based simulation system close to the environment of low Earth orbit. Changes in characteristics including surface morphology, mechanical properties, optical and electrical properties were compared between IWO and ITO films after AO irradiation. The effects of AO irradiation on transparent conductive oxide thin films were analyzed. As a result, AO has influences on ITO and IWO thin films through the way of oxidation and erosion. Both ITO and IWO films possess suitable anti-AO properties. IWO films are more appropriate as AO protective coatings due to their compact microstructure, the coexistence of W 4+ and W 6+ ions in their chemical systems, and incremental WO 3 protective layer under AO oxidation.
Improved performance of co-sputtered Ni–Ti oxide films for all-solid-state electrochromic devices
RSC Advances, 2016
Thin films of Ni–Ti oxide were co-sputtered by reactive direct current magnetron sputtering and t... more Thin films of Ni–Ti oxide were co-sputtered by reactive direct current magnetron sputtering and their structures, morphologies, and compositions were investigated by X-ray diffraction, atomic force microscopy and X-ray photo-electron spectroscopy.