Chromium (Cr) doped Zinc oxide ZnO thin films were deposited onto glass substrates by Metal Organic Chemical Vapour Deposition (MOCVD) technique with varying dopant concentration at a temperature of 420°C. The ef...Chromium (Cr) doped Zinc oxide ZnO thin films were deposited onto glass substrates by Metal Organic Chemical Vapour Deposition (MOCVD) technique with varying dopant concentration at a temperature of 420°C. The effect of the chromium concentration on morphological, structural, optical, electrical and gas sensing properties of the films were investigated. The scanning electron microscopy results revealed that the Cr concentration has great influence on the crystallinity, surface smoothness and grain size. X-ray diffraction (XRD) studies shows that films were polycrystalline in nature and grown as a hexagonal wurtzite structure. A direct optical band energy gap of 3.32 to 3.10 eV was obtained from the optical measurements. The transmission was found to decrease with increasing Cr doping concentration. Rutherford Backscattering Spectroscopy (RBS) analysis also demonstrates that Cr ions are substitutionally incorporated into ZnO. I-V characteristic of the film shows a resistivity ranges from 1.134 × 10-2 · cm to 1.24 × 10-2 · cm at room temperature. The gas sensing response of the films were enhanced with incorporation of Cr as a dopant with optimum operating temperature around 200°C.展开更多
Thin films and thin film devices have a ubiquitous presence in numerous conventional and emerging technologies. This is because of the recent advances in nanotechnology, the development of functional and smart materia...Thin films and thin film devices have a ubiquitous presence in numerous conventional and emerging technologies. This is because of the recent advances in nanotechnology, the development of functional and smart materials,conducting polymers, molecular semiconductors, carbon nanotubes, and graphene, and the employment of unique properties of thin films and ultrathin films, such as high surface area, controlled nanostructure for effective charge transfer, and special physical and chemical properties, to develop new thin film devices. This paper is therefore intended to provide a concise critical review and research directions on most thin film devices, including thin film transistors, data storage memory, solar cells, organic light-emitting diodes, thermoelectric devices, smart materials, sensors, and actuators. The thin film devices may consist of organic, inorganic, and composite thin layers, and share similar functionality, properties, and fabrication routes. Therefore, due to the multidisciplinary nature of thin film devices, knowledge and advances already made in one area may be applicable to other similar areas. Owing to the importance of developing low-cost, scalable, and vacuum-free fabrication routes, this paper focuses on thin film devices that may be processed and deposited from solution.展开更多
There are various technologies like CVD. Radio Frequency sputtering, spin coating etc. present for thin film deposition for various applications and for gas sensors. In this review, special attention is focused on the...There are various technologies like CVD. Radio Frequency sputtering, spin coating etc. present for thin film deposition for various applications and for gas sensors. In this review, special attention is focused on the thin film deposition for gas sensing applications by using Langmuir Blodgett method. Langmuir Blodgett method also discussed briefly. Modified technique of Langmuir-Blodgett like Langmuir Schaefer method is discussed and various examples of Langmuir Blodgett techniques for gas sensing for space applications are included. Future prospects of gas sensing thin film deposition by Langmuir Blodgett technique are explained.展开更多
Covalent organic frameworks(COFs)are an emerging type of porous crystalline polymers formed by combining strong covalent bonds with organic building blocks.Due to their large surface area,high intrinsic pore space,goo...Covalent organic frameworks(COFs)are an emerging type of porous crystalline polymers formed by combining strong covalent bonds with organic building blocks.Due to their large surface area,high intrinsic pore space,good crystallization properties,high stability,and designability of the resultant units,COFs are widely studied and used in the fields of gas adsorption,drug transport,energy storage,photoelectric catalysis,electrochemistry,and sensors.In recent years,the rapid development of the Internet of Things and people’s yearning for a better life have put forward higher and more requirements for sensors,which are the core components of the Internet of Things.Therefore,this paper reviews the recent progress of COFs in synthesis methods and sensing applications,especially in the last five years.This paper first introduces structure,properties,and synthesis methods of COFs and discusses advantages and disadvantages of different synthesis methods.Then,the research progress of COFs in different sensing fields,such as metal ion sensors,gas sensors,biomedical sensors,humidity sensors,and pH sensors,is introduced systematically.Conclusions and prospects are also presented in order to provide a reference for researchers concerned with COFs and sensors.展开更多
Gas sensors based on organic semiconductors receive tremendous attentions owing to their advantages on high selectivity and room temperature operation. However, until now, most organic semiconductor based sensors stil...Gas sensors based on organic semiconductors receive tremendous attentions owing to their advantages on high selectivity and room temperature operation. However, until now, most organic semiconductor based sensors still suffered from problems, such as low sensitivity, slow response/recovery speed and poor stability. In addition, a clear correlation between the sensing performance and the film property is still absent. Herein, we report the investigation on sensing performance of a series of organic films with various morphologies. By simply adjusting the quality of self-assembled monolayer(SAM) on the silicon wafer surface, we obtain organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) films with varied morphologies and different charge transport abilities. The film with a small grain size and a continuous morphology presents the highest sensing performance to NO2, with a sensitivity up to 730%/ppm(ppm=parts per million, vo-lume ratio). We thus reveal that the high sensitivity of the organic film is evident related with the charge transport ability and initial conductivity of the films, as well as the morphologies of both modification layer and the active films.展开更多
The spreading behavior of new type of chiral and achiral rigid cyclic oligomer on the water surface was investigated by measuring the surface pressure(π) area( A ) isotherms, with the aim of comparison of new type LB...The spreading behavior of new type of chiral and achiral rigid cyclic oligomer on the water surface was investigated by measuring the surface pressure(π) area( A ) isotherms, with the aim of comparison of new type LB films of chiral and achiral rigid cyclic oligomers. Molecular resolution atomic force microscope images of the Langmuir Blodgett(LB) film was observed and the structure of their two dimensional crystals on the basal plane of mica was studied.展开更多
Organic thermoelectric(OTE)materials have been considered to be promising candidates for large area and low‐cost wearable devices owing to their tailorable molecular structure,intrinsic flexibility,and prominent solu...Organic thermoelectric(OTE)materials have been considered to be promising candidates for large area and low‐cost wearable devices owing to their tailorable molecular structure,intrinsic flexibility,and prominent solution processability.More importantly,OTE materials offer direct energy conversion from the human body,solid‐state cooling at low electric consumption,and diversified functions.Herein,we summarize recent developments of OTE materials and devices for smart applications.We first review the fundamentals of OTE materials from the viewpoint of thermoelectric performance,mechanical properties and bionic functions.Second,we describe OTE devices in flexible generators,photothermoelectric detectors,self‐powered sensors,and ultra‐thin cooling elements.Finally,we present the challenges and perspectives on OTE materials as well as devices in wearable electronics and fascinating applications in the Internet of Things.展开更多
Drug abuse directly endangers human health and social security,hence its sensitive and rapid detection is vitally important.In recent years,organic film-based fluorescent sensing technology has attracted more and more...Drug abuse directly endangers human health and social security,hence its sensitive and rapid detection is vitally important.In recent years,organic film-based fluorescent sensing technology has attracted more and more attention in the detection of drugs and explosives due to its advantages of simple operation and rapid detection.For film-based fluorescent sensors,in addition to sensitive materials,the surface morphology of the film is also an important factor affecting the performance.In previous studies,the regulation of surface morphology mainly depends on concentration changes or complex templates.Here,a novel fluorescent polymer probe was designed and synthesized,and a simple and efficient ultraviolet(UV)-ozone substrate treatment method is used to adjust their surface morphology.The results show that film has an excellent fluorescence enhancement effect upon exposure to methylphenethylamine(MPEA,a simulant of methamphetamine)vapor.The sensing effect of the film is significantly improved after UV-ozone substrate treatment,and the limit of detection was decreased by 10.4 times from 2.59 to 0.25 ppm.Further experiments show that the sensing performance of other fluorescent probe can also be improved by the UV-ozone substrate treatment.This convenient and general method may become a very effective approach to improve the performance of film-based fluorescent sensors.展开更多
In this work,the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate.The reaction temperature,heating rate,holding time and carrier gas flow rate were inve stigated com...In this work,the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate.The reaction temperature,heating rate,holding time and carrier gas flow rate were inve stigated compre hensively.The quality of MoS2 film was characterized by optical microscopy,atomic fo rce microscopy,Raman and photoluminescence spectro scopy.The characte rization results showed that the optimum synthesis parameters were heating rate of 25℃/min,reaction temperature of 750℃,holding time of 30 min and carrier gas velocity of 100 sccm.The MoS2 gas sensor was fabricated and its gas sensing performance was tested.The test results indicated that the sensor had a good response to both reducing gas(NH3)and oxidizing gas(NO2)at room temperature.The sensitivity to 100 ppm of NO2 was 31.3%,and the response/recovery times were 4 s and 5 s,respectively.In addition,the limit of detection could be as low as 1 ppm.This work helps us to develop low power and integrable room temperature NO2 sensors.展开更多
文摘Chromium (Cr) doped Zinc oxide ZnO thin films were deposited onto glass substrates by Metal Organic Chemical Vapour Deposition (MOCVD) technique with varying dopant concentration at a temperature of 420°C. The effect of the chromium concentration on morphological, structural, optical, electrical and gas sensing properties of the films were investigated. The scanning electron microscopy results revealed that the Cr concentration has great influence on the crystallinity, surface smoothness and grain size. X-ray diffraction (XRD) studies shows that films were polycrystalline in nature and grown as a hexagonal wurtzite structure. A direct optical band energy gap of 3.32 to 3.10 eV was obtained from the optical measurements. The transmission was found to decrease with increasing Cr doping concentration. Rutherford Backscattering Spectroscopy (RBS) analysis also demonstrates that Cr ions are substitutionally incorporated into ZnO. I-V characteristic of the film shows a resistivity ranges from 1.134 × 10-2 · cm to 1.24 × 10-2 · cm at room temperature. The gas sensing response of the films were enhanced with incorporation of Cr as a dopant with optimum operating temperature around 200°C.
基金Research funding from the Shanghai Municipal Education Commission in the framework of the oriental scholar and distinguished professor designationfunding from the National Natural Science Foundation of China(NSFC)
文摘Thin films and thin film devices have a ubiquitous presence in numerous conventional and emerging technologies. This is because of the recent advances in nanotechnology, the development of functional and smart materials,conducting polymers, molecular semiconductors, carbon nanotubes, and graphene, and the employment of unique properties of thin films and ultrathin films, such as high surface area, controlled nanostructure for effective charge transfer, and special physical and chemical properties, to develop new thin film devices. This paper is therefore intended to provide a concise critical review and research directions on most thin film devices, including thin film transistors, data storage memory, solar cells, organic light-emitting diodes, thermoelectric devices, smart materials, sensors, and actuators. The thin film devices may consist of organic, inorganic, and composite thin layers, and share similar functionality, properties, and fabrication routes. Therefore, due to the multidisciplinary nature of thin film devices, knowledge and advances already made in one area may be applicable to other similar areas. Owing to the importance of developing low-cost, scalable, and vacuum-free fabrication routes, this paper focuses on thin film devices that may be processed and deposited from solution.
文摘There are various technologies like CVD. Radio Frequency sputtering, spin coating etc. present for thin film deposition for various applications and for gas sensors. In this review, special attention is focused on the thin film deposition for gas sensing applications by using Langmuir Blodgett method. Langmuir Blodgett method also discussed briefly. Modified technique of Langmuir-Blodgett like Langmuir Schaefer method is discussed and various examples of Langmuir Blodgett techniques for gas sensing for space applications are included. Future prospects of gas sensing thin film deposition by Langmuir Blodgett technique are explained.
基金funded by the National Natural Science Foundation of China(No.21964016)Xinjiang National Science Fund for Distinguished Young Scholars(No.2022D01E37)+1 种基金Key programs of Xinjiang Natural Science Foundation(No.2022B02051)Tianshan Innovation Team Program of Xinjiang Uygur Autonomous Region(No.2020D14038).
文摘Covalent organic frameworks(COFs)are an emerging type of porous crystalline polymers formed by combining strong covalent bonds with organic building blocks.Due to their large surface area,high intrinsic pore space,good crystallization properties,high stability,and designability of the resultant units,COFs are widely studied and used in the fields of gas adsorption,drug transport,energy storage,photoelectric catalysis,electrochemistry,and sensors.In recent years,the rapid development of the Internet of Things and people’s yearning for a better life have put forward higher and more requirements for sensors,which are the core components of the Internet of Things.Therefore,this paper reviews the recent progress of COFs in synthesis methods and sensing applications,especially in the last five years.This paper first introduces structure,properties,and synthesis methods of COFs and discusses advantages and disadvantages of different synthesis methods.Then,the research progress of COFs in different sensing fields,such as metal ion sensors,gas sensors,biomedical sensors,humidity sensors,and pH sensors,is introduced systematically.Conclusions and prospects are also presented in order to provide a reference for researchers concerned with COFs and sensors.
基金supported by the National Key Research and Development Program of China(No.2018YFE0200700)the National Natural Science Foundation of China(Nos.51773143,51821002)the Fund of the German-Chinese Transregional Collaborative Research Centre TRR 61(No.21661132006)。
文摘Gas sensors based on organic semiconductors receive tremendous attentions owing to their advantages on high selectivity and room temperature operation. However, until now, most organic semiconductor based sensors still suffered from problems, such as low sensitivity, slow response/recovery speed and poor stability. In addition, a clear correlation between the sensing performance and the film property is still absent. Herein, we report the investigation on sensing performance of a series of organic films with various morphologies. By simply adjusting the quality of self-assembled monolayer(SAM) on the silicon wafer surface, we obtain organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) films with varied morphologies and different charge transport abilities. The film with a small grain size and a continuous morphology presents the highest sensing performance to NO2, with a sensitivity up to 730%/ppm(ppm=parts per million, vo-lume ratio). We thus reveal that the high sensitivity of the organic film is evident related with the charge transport ability and initial conductivity of the films, as well as the morphologies of both modification layer and the active films.
文摘The spreading behavior of new type of chiral and achiral rigid cyclic oligomer on the water surface was investigated by measuring the surface pressure(π) area( A ) isotherms, with the aim of comparison of new type LB films of chiral and achiral rigid cyclic oligomers. Molecular resolution atomic force microscope images of the Langmuir Blodgett(LB) film was observed and the structure of their two dimensional crystals on the basal plane of mica was studied.
基金supported by the National Key Research and Development Program of China(2017YFA0204700 and 2018YFE0200700)the National Natural Science Foundation of China(21805285,22021002,21905276,61971396)+2 种基金the Natural Science Foundation of Beijing(4202077)Beijing National Laboratory for Molecular Sciences(BNLMS201912)UCAS(Y954011XX2)and CAS(ZDBS‐LY‐SLH034).
文摘Organic thermoelectric(OTE)materials have been considered to be promising candidates for large area and low‐cost wearable devices owing to their tailorable molecular structure,intrinsic flexibility,and prominent solution processability.More importantly,OTE materials offer direct energy conversion from the human body,solid‐state cooling at low electric consumption,and diversified functions.Herein,we summarize recent developments of OTE materials and devices for smart applications.We first review the fundamentals of OTE materials from the viewpoint of thermoelectric performance,mechanical properties and bionic functions.Second,we describe OTE devices in flexible generators,photothermoelectric detectors,self‐powered sensors,and ultra‐thin cooling elements.Finally,we present the challenges and perspectives on OTE materials as well as devices in wearable electronics and fascinating applications in the Internet of Things.
基金supported by the National Natural Science Foundation of China(Nos.62022085,61901456,61831021,61731016,and 61771460)the National Key R&D Program of China(No.2018AAA0103100)the Science and Technology Commission of Shanghai Municipality(Nos.19YF1455700 and 19142203500).
文摘Drug abuse directly endangers human health and social security,hence its sensitive and rapid detection is vitally important.In recent years,organic film-based fluorescent sensing technology has attracted more and more attention in the detection of drugs and explosives due to its advantages of simple operation and rapid detection.For film-based fluorescent sensors,in addition to sensitive materials,the surface morphology of the film is also an important factor affecting the performance.In previous studies,the regulation of surface morphology mainly depends on concentration changes or complex templates.Here,a novel fluorescent polymer probe was designed and synthesized,and a simple and efficient ultraviolet(UV)-ozone substrate treatment method is used to adjust their surface morphology.The results show that film has an excellent fluorescence enhancement effect upon exposure to methylphenethylamine(MPEA,a simulant of methamphetamine)vapor.The sensing effect of the film is significantly improved after UV-ozone substrate treatment,and the limit of detection was decreased by 10.4 times from 2.59 to 0.25 ppm.Further experiments show that the sensing performance of other fluorescent probe can also be improved by the UV-ozone substrate treatment.This convenient and general method may become a very effective approach to improve the performance of film-based fluorescent sensors.
基金supports from the National Natural Science Foundation of China(Nos.51572173,51602197,51771121 and 51702212)Shanghai Municipal Science and Technology Commission(Nos.19ZR1435200,18511110600 and 19JC1410402)+1 种基金Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00015)Shanghai Academic/Technology Research Leader Program(No.19XD1422900)。
文摘In this work,the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate.The reaction temperature,heating rate,holding time and carrier gas flow rate were inve stigated compre hensively.The quality of MoS2 film was characterized by optical microscopy,atomic fo rce microscopy,Raman and photoluminescence spectro scopy.The characte rization results showed that the optimum synthesis parameters were heating rate of 25℃/min,reaction temperature of 750℃,holding time of 30 min and carrier gas velocity of 100 sccm.The MoS2 gas sensor was fabricated and its gas sensing performance was tested.The test results indicated that the sensor had a good response to both reducing gas(NH3)and oxidizing gas(NO2)at room temperature.The sensitivity to 100 ppm of NO2 was 31.3%,and the response/recovery times were 4 s and 5 s,respectively.In addition,the limit of detection could be as low as 1 ppm.This work helps us to develop low power and integrable room temperature NO2 sensors.
