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Wenchang Chen - One of the best experts on this subject based on the ideXlab platform.
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multilevel photonic transistor memory devices using conjugated insulated polymer blend Electrets
ACS Applied Materials & Interfaces, 2019Co-Authors: Chienchung Shih, Yunchi Chiang, Huiching Hsieh, Yancheng Lin, Wenchang ChenAbstract:Photonic data storage has diverse optoelectronic applications such as optical sensing and recording, integrated image circuits, and multibit-storage flash memory. In this study, we employ conjugated/insulated polymer blends as the charge storage electret for photonic field-effect transistor memory devices by exploring the blend composition, energy level alignment, and morphology on the memory characteristics. The studied conjugated polymers included poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PF), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[{2,5-di(3',7'-dimethyloctyloxy)-1,4-phenylene-vinylene}-co-{3-(4'-(3″,7″-dimethyloctyloxy)phenyl)-1,4-phenylenevinylene}-co-{3-(3'-(3',7'-dimethyloctyloxy)phenyl)-1,4-phenylenevinylene}] (SY-PPV), and poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT), and the insulated polymers were polystyrene (PS) and poly(methyl methacrylate) (PMMA). The photonic memory device using the PF/PS blend electret exhibited a dynamic switching behavior with light-writing and voltage-erasing processes both within only 1 s, along with a high contrast on the current on/off ratio between "Photo-On" and "Electrical-OFF" over 106 and the decent retention time for more than 3 months. In addition, the multilevel memory behavior could be observed using different light sources of 405, 450, and 520 nm or energy intensity, which was supported by surface potential analysis. The characteristics were superior to those of the devices using PF/PMMA blend due to the higher charge storage behavior of PS supported by fluorescence analysis. The PF/PS blend film prepared from the chlorobenzene solvent exhibited mesh-like and aggregated PF domains in the PS matrix and enhanced the contact surface area between the semiconductor and blend electret, leading to a higher memory window. The photonic memory behavior was also observed in the blend Electrets of PS with the low band gap polymer, MEH-PPV, SY-PPV, or F8BT, by changing the photoresponsive light sources. Our study demonstrated a new electret system to apply on the multilevel photonic memory devices.
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non volatile organic transistor memory devices using the poly 4 vinylpyridine based supramolecular Electrets
Chemical Communications, 2015Co-Authors: Yuhsiang Chou, Yucheng Chiu, Wenya Lee, Wenchang ChenAbstract:Supramolecular Electrets consisting of poly(4-vinylpyridine) (P4VP) and conjugated molecules of phenol, 2-naphthol and 2-hydroxyanthracene were investigated for non-volatile transistor memory applications. The memory windows of these supramolecular electret devices were significantly enhanced upon increasing the π-conjugation size of the molecule. A high ON/OFF current ratio of more than 107 over 104 s was achieved on the supramolecule based memory devices.
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nonvolatile memories using the Electrets of conjugated rod coil block copolymer and its nanocomposite with single wall carbon nanotubes
Journal of Materials Chemistry C, 2015Co-Authors: Yucheng Chiu, Chienchung Shih, Wenchang ChenAbstract:We report high performance pentacene based organic field-effect transistor (OFET) memory devices using the Electrets of conjugated rod-coil block copolymers, poly[2,7-(9,9-dihexylfluorene)]-block-poly(stearyl acrylate) (PF-b-PSA) and their nanocomposites with single-wall carbon nanotubes (SWCNT). The self-assembled PF-b-PSA electret, with the PF nanorods covered by the crystalline PSA block, exhibited a distinct hole-trapping capability due to the high electrical field generated in the confined dimension of the nanorods. Thus, it could effectively reduce the current leakage and stabilize data retention with a large memory window (35.8 V) and a high ON/OFF ratio over 104 s. Furthermore, the memory window of the device was further improved to 49.2 V by wrapping well-dispersed single-wall carbon nanotubes (SWCNT) in PF-b-PSA. The bundles of PF nanorods along the SWCNT effectively capture electrons and maintain retention characteristics similar to that of the PF-b-PSA device. This study demonstrated that the self-assembled conjugated rod-coil block copolymers and their nanocomposites could act as charge-storage Electrets for high performance OFET memory devices through the precise morphology control.
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high performance nonvolatile organic transistor memory devices using the Electrets of semiconducting blends
ACS Applied Materials & Interfaces, 2014Co-Authors: Yucheng Chiu, Tzuying Chen, Yougen Chen, Toshifumi Satoh, Toyoji Kakuchi, Wenchang ChenAbstract:Organic nonvolatile transistor memory devices of the n-type semiconductor N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) were prepared using various Electrets (i.e., three-armed star-shaped poly[4-(diphenylamino)benzyl methacrylate] (N(PTPMA)3) and its blends with 6,6-phenyl-C61-butyric acid methyl ester (PCBM), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pen) or ferrocene). In the device using the PCBM:N(PTPMA)3 blend electret, it changed its memory feature from a write-once-read-many (WORM) type to a flash type as the PCBM content increased and could be operated repeatedly based on a tunneling process. The large shifts on the reversible transfer curves and the hysteresis after implementing a gate bias indicated the considerable charge storage in the electret layer. On the other hand, the memory characteristics showed a flash type and a WORM characteristic, respectively, using the donor/donor Electrets TIPS-pen:N(PTPMA)3 and ferrocene:N(PTPMA)3. The variation on the m...
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nonvolatile organic field effect transistor memory devices using polymer Electrets with different thiophene chain lengths
Polymer Chemistry, 2014Co-Authors: Yinghsuan Chou, Sanae Takasugi, Raita Goseki, Takashi Ishizone, Wenchang ChenAbstract:We report the synthesis of poly(5-hexyl-2-vinylthiophene) (PVT) and poly(5-hexyl-5′′-vinyl-2,2′:5,2′′-terthiophene) (PVTT) as charge storage Electrets for nonvolatile organic field effect transistor (OFET) memory devices of n-type semiconducting N,N′-bis(2-phenylethyl)perylene-3,4,9,10-bis(dicarboximide) (BPE-PTCDI). The effects of the conjugated thiophene chain length on the morphology, OFET mobility and memory characteristics are explored and compared to those of the styrene or fluorene side chain. The mobility of the OFET memory device using PVTT as an electret is significantly smaller compared with that of PVT because its large torsional angle hinders the molecular packing of BPE-PTCDI. However, the OFET memory device using the PVTT electret has the largest hysteresis window of 81 V, compared to PVT, polystyrene (PS), and poly(styrene) para-substituted with fluorene (PSt-Fl). The highest HOMO energy level of PVTT facilitates the charge transfer from BPE-PTCDI and leads to the largest memory window. The backbone non-coplanarity prevents the back transfer of the charge for the nonvolatile memory characteristics. The device shows excellent nonvolatile behavior for bistable switching and the write–read–erase–read (WRER) cycles are operated over 100 cycles. The shifted threshold voltages of the OFET memory devices using PVTT are stable over 104 s, and the ON and OFF states could maintain 104 s with the Ion/Ioff current ratios of 103. This study suggests that the pendent conjugation length and the backbone coplanarity of polymer Electrets significantly affect the charge mobility and electrical characteristics of OFET memory devices.
Yucheng Chiu - One of the best experts on this subject based on the ideXlab platform.
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donor acceptor effect of carbazole based conjugated polymer Electrets on photoresponsive flash organic field effect transistor memories
ACS Applied Materials & Interfaces, 2020Co-Authors: Chiahui Chen, Yucheng Chiu, Yang Wang, Tsuyoshi Michinobu, Shuwei Chang, Guey-sheng LiouAbstract:The molecular structure of polymer Electrets is crucial for creating diverse functionalities of organic field-effect transistor (OFET) devices. Herein, a conceptual framework has been applied in this study to design the highly photoresponsive carbazole-based copolymer electret materials for the application of photoresponsive OFET memory. As an electret layer, two 1,8-carbazole-based copolymers were utilized; the copoly(CT) consisted of carbazole as the donor group and thiophene as the π-spacer, whereas the copoly(CBT) was further introduced as an acceptor moiety, benzothiadiazole, for comparison. Both copolymers exhibited efficient visible-light absorption and photoluminescence quenching in the film state, indicating the formation of a considerable number of nonemissive excitons, one of the crucial factors for achieving photoinduced recovery behavior in OFET memories. Compared to copoly(CT) with the pure donor system, faster and more effective photoinduced recovery behavior was discovered in the copoly(CBT) with the conjugated donor-acceptor structure because of the coexistence of the conjugated donor and acceptor groups. Thus, the dissociation of the generated excitons facilitated the stimulating of the unique ambipolar trapping property, resulting in the high-density data storage devices with multilevel current states. In addition, the nonvolatile and durable characteristics demonstrated the feasibility in application of memory and photorecorders.
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non volatile organic transistor memory devices using the poly 4 vinylpyridine based supramolecular Electrets
Chemical Communications, 2015Co-Authors: Yuhsiang Chou, Yucheng Chiu, Wenya Lee, Wenchang ChenAbstract:Supramolecular Electrets consisting of poly(4-vinylpyridine) (P4VP) and conjugated molecules of phenol, 2-naphthol and 2-hydroxyanthracene were investigated for non-volatile transistor memory applications. The memory windows of these supramolecular electret devices were significantly enhanced upon increasing the π-conjugation size of the molecule. A high ON/OFF current ratio of more than 107 over 104 s was achieved on the supramolecule based memory devices.
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nonvolatile memories using the Electrets of conjugated rod coil block copolymer and its nanocomposite with single wall carbon nanotubes
Journal of Materials Chemistry C, 2015Co-Authors: Yucheng Chiu, Chienchung Shih, Wenchang ChenAbstract:We report high performance pentacene based organic field-effect transistor (OFET) memory devices using the Electrets of conjugated rod-coil block copolymers, poly[2,7-(9,9-dihexylfluorene)]-block-poly(stearyl acrylate) (PF-b-PSA) and their nanocomposites with single-wall carbon nanotubes (SWCNT). The self-assembled PF-b-PSA electret, with the PF nanorods covered by the crystalline PSA block, exhibited a distinct hole-trapping capability due to the high electrical field generated in the confined dimension of the nanorods. Thus, it could effectively reduce the current leakage and stabilize data retention with a large memory window (35.8 V) and a high ON/OFF ratio over 104 s. Furthermore, the memory window of the device was further improved to 49.2 V by wrapping well-dispersed single-wall carbon nanotubes (SWCNT) in PF-b-PSA. The bundles of PF nanorods along the SWCNT effectively capture electrons and maintain retention characteristics similar to that of the PF-b-PSA device. This study demonstrated that the self-assembled conjugated rod-coil block copolymers and their nanocomposites could act as charge-storage Electrets for high performance OFET memory devices through the precise morphology control.
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high performance nonvolatile organic transistor memory devices using the Electrets of semiconducting blends
ACS Applied Materials & Interfaces, 2014Co-Authors: Yucheng Chiu, Tzuying Chen, Yougen Chen, Toshifumi Satoh, Toyoji Kakuchi, Wenchang ChenAbstract:Organic nonvolatile transistor memory devices of the n-type semiconductor N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) were prepared using various Electrets (i.e., three-armed star-shaped poly[4-(diphenylamino)benzyl methacrylate] (N(PTPMA)3) and its blends with 6,6-phenyl-C61-butyric acid methyl ester (PCBM), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pen) or ferrocene). In the device using the PCBM:N(PTPMA)3 blend electret, it changed its memory feature from a write-once-read-many (WORM) type to a flash type as the PCBM content increased and could be operated repeatedly based on a tunneling process. The large shifts on the reversible transfer curves and the hysteresis after implementing a gate bias indicated the considerable charge storage in the electret layer. On the other hand, the memory characteristics showed a flash type and a WORM characteristic, respectively, using the donor/donor Electrets TIPS-pen:N(PTPMA)3 and ferrocene:N(PTPMA)3. The variation on the m...
S Boisseau - One of the best experts on this subject based on the ideXlab platform.
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New DRIE-Patterned Electrets for Vibration Energy Harvesting
2016Co-Authors: S Boisseau, -b. A. Duret, -j. J. Chaillout, G DespesseAbstract:Abstract. This paper is about a new manufacturing process aimed at developing stable SiO2/Si3N4 patterned Electrets using a Deep Reactive Ion Etching (DRIE) step for an application in electret-based Vibration Energy Harvesters (e-VEH). This process consists in forming continuous layers of SiO2/Si3N4 Electrets in order to limit surface conduction phenomena and is a new way to see the problem of electret patterning. Experimental results prove that patterned Electrets charged by a positive corona discharge show excellent stability with high surface charge densities that may reach 5mC/m on 1.1µm-thick layers, even with fine patterning and harsh temperature conditions (up to 250°C). This paves the way to new e-VEH designs and manufacturing processes.
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Low-Frequency MEMS Electrostatic Vibration Energy Harvester With Corona-Charged Vertical Electrets and Nonlinear Stoppers
2015Co-Authors: F Cottone, S Boisseau, Dimitri Galayko, Frédéric Marty, Philippe BassetAbstract:This paper reports for the first time a MEMS electrostatic vibration energy harvester (e-VEH) with corona-charged vertical Electrets on its electrodes. The bandwidth of the 1-cm2 device is extended in low and high frequencies by nonlinear elastic stoppers. With a bias voltage of 46 V (electret@21 V + DC external source@25 V) between the electrodes, the RMS power of the device reaches 0.89 μW at 33 Hz and 6.6 μW at 428 Hz. The -3dB frequency band including the hysteresis is 223~432 Hz, the one excluding the hysteresis 88~166 Hz. We also demonstrate the charging of a 47 μF capacitor used for powering a wireless and autonomous temperature sensor node with a data transmission beyond 10 m at 868 MHz.
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semi flexible bimetal based thermal energy harvesters
Smart Materials and Structures, 2013Co-Authors: S Boisseau, G Despesse, S Monfray, Onoriu Puscasu, Thomas SkotnickiAbstract:This paper introduces a new semi-flexible device able to turn thermal gradients into electricity by using a curved bimetal coupled to an electret-based converter. In fact, a two-step conversion is carried out: (i) a curved bimetal turns the thermal gradient into a mechanical oscillation that is then (ii) converted into electricity thanks to an electrostatic converter using Electrets in Teflon?. The semi-flexible and low-cost design of these new energy converters pave the way to mass production over large areas of thermal energy harvesters. Raw output powers up to 13.46??W per device were reached on a hot source at 60??C?with forced convection. Then, a DC-to-DC flyback converter has been sized to turn the energy harvesters? raw output powers into a viable supply source for an electronic circuit (DC@3?V). At the end, 10??W of directly usable output power were reached with 3 devices, which is compatible with wireless sensor network powering applications.
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cantilever based electret energy harvesters
Smart Materials and Structures, 2011Co-Authors: S Boisseau, Ghislain Despesse, Thibaud Ricart, Emmanuel Defay, A SylvestreAbstract:Integration of structures and functions has permitted the electricity consumption of sensors, actuators and electronic devices to be reduced. Therefore, it is now possible to imagine low-consumption devices able to harvest energy from their surrounding environment. One way to proceed is to develop converters able to turn mechanical energy, such as vibrations, into electricity: this paper focuses on electrostatic converters using Electrets. We develop an accurate analytical model of a simple but efficient cantilever-based electret energy harvester. We prove that with vibrations of 0.1g (~1 m s−2), it is theoretically possible to harvest up to 30 µW per gram of mobile mass. This power corresponds to the maximum output power of a resonant energy harvester according to the model of William and Yates. Simulation results are validated by experimental measurements, raising at the same time the large impact of parasitic capacitances on the output power. Therefore, we 'only' managed to harvest 10 µW per gram of mobile mass, but according to our factor of merit, this is among the best results so far achieved.
Fei Wang - One of the best experts on this subject based on the ideXlab platform.
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electret material enhanced triboelectric energy harvesting from air flow for self powered wireless temperature sensor network
Sensors and Actuators A-physical, 2018Co-Authors: Yingchun Wu, Yushen Hu, Ziyu Huang, Fei WangAbstract:Abstract Energy from wind flow is very common in ambient environment which can be harvested by triboelectric generator effectively. Herein, electret based triboelectric generator (E-TriG) with both electrostatic and triboelectric effects are investigated with enhanced performance comparing with the traditional triboelectric generator based on only contact electrification. Electret materials like PTFE, CYTOP, TOPAS, and COC are prepared with different methods and charged under positive or negative conditions to optimize the material property. It is proved that the performance of the triboelectric generator can be improved by negatively charged Electrets, while with positively charged Electrets, the power output is weakened. As a demonstration, the E-TriG has been successfully applied for wireless temperature sensing. At a wind flow rate of 18 m/s, a storage capacitor can be fully charged by three E-TriGs devices within 15 s, and afterwards, wireless temperature signal could be read and delivered to the internet every 5 s. An average power of 400 μW is therefore harvested. With enhanced performance from the corona charged electret, the triboelectric generator shows promising application for the future wireless sensor networks.
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spray coating of polymer electret with polystyrene nanoparticles for electrostatic energy harvesting
Micro & Nano Letters, 2016Co-Authors: Anxin Luo, Ai Zhang, Yulong Zhang, Bin Tang, Kai Wang, Fei WangAbstract:A spray-coating method for cyclic olefin copolymer (COC) electret material with polystyrene (PS) nanoparticles is developed here. Compared with the traditional polymer electret materials, the COC Electrets with PS nanoparticles achieved better surface charge stability when exposed to harsh environment at high humidity or high temperature. With the spray coating technique, they can easily control the thickness of the electret layer. The surface charge stability of the electret has been detailed studied with various concentrations of the nanoparticles. They have also applied the spray coated electret to electrostatic energy harvesting devices. The experiments confirmed that the energy harvesting devices can generate more stable power output using the spray coated electret with nanoparticles.
Sebastien Boisseau - One of the best experts on this subject based on the ideXlab platform.
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a cm scale electret based electrostatic wind turbine for low speed energy harvesting applications
Smart Materials and Structures, 2016Co-Authors: Matthias Perez, Sebastien Boisseau, P Gasnier, J Willemin, M Geisler, J L ReboudAbstract:This paper presents a small-scale airflow energy harvester built on an axial turbine architecture and exploiting an electret-based electrostatic converter. When the airflow velocity is high enough, the windmill starts rotating and creates a periodic relative motion between a stator and a rotor which induces variations of capacitance. These ones are directly converted into electricity thanks to the use of Teflon Electrets charged at −1400 V which polarize the variable capacitors. We focus our study on a 4-blade axial turbine with a diameter of D = 40 mm, a depth of W = 10 mm, for a total volume of 12.6 cm3. This windmill has been tested with various blade angles and different types of electrostatic converters and output powers up to 90 μW at 1.5 m s−1 (7.5 μW cm−3) and 1.8 mW at 10 m s−1 (111 μW cm−3) have been obtained so far. The coefficient of power reaches C p = 5.8% and among the small-scale airflow energy harvesters previously reported, this one has the lowest cut-in speed (1.5 m s−1).
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optimization of an electret based energy harvester
arXiv: Classical Physics, 2011Co-Authors: Sebastien Boisseau, Ghislain Despesse, Alain SylvestreAbstract:Thanks to miniaturisation, it is today possible to imagine self-powered systems that use vibrations to produce their own electrical energy. Many energy-harvesting systems already exist. Some of them are based on the use of Electrets: electrically charged dielectrics that can keep charges for years. This paper presents an optimisation of an existing system and proves that electret-based electrostatic energy scavengers can be excellent solutions to power microsystems even with low-level ambient vibrations. Thereby, it is possible to harvest up to 200\muW with vibrations lower than 1G of acceleration (typically 50\mumpp at 50Hz) using thin SiO2 Electrets with an active surface of 1 cm^{2} and a mobile mass of 1g. This paper optimises such a system (geometric, electrostatic and mechanical parameters), using FEM (Finite Element Method) software (Comsol Multiphysics) and Matlab to compute the parameters and proves the importance of such an optimisation to build efficient systems. Finally, it shows that the use of Electrets with high surface potential is not always the best way to maximise output power.
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optimization of an electret based energy harvester
Smart Materials and Structures, 2010Co-Authors: Sebastien Boisseau, Ghislain Despesse, Alain SylvestreAbstract:Thanks to miniaturization, it is now possible to imagine self-powered systems that use vibrations to produce their own electrical energy. Many energy harvesting systems already exist. Some of them are based on the use of Electrets: electrically charged dielectrics that can retain charge for years. This paper presents an optimization of an existing system and proves that electret-based electrostatic energy scavengers can be excellent solutions to power microsystems even with low-level ambient vibrations. Thereby, it is possible to harvest up to 200??W with vibrations of acceleration lower than 1g (typically 50? ?mpp at 50?Hz) using thin SiO2 Electrets with an active surface of 1?cm2 and a mobile mass of 1?g. This paper optimizes such a system (geometric, electrostatic and mechanical parameters), using FEM (finite element method) software (Comsol Multiphysics) and Matlab to compute the parameters, and proves the importance of such an optimization to build efficient systems. Finally, it is shown that the use of Electrets with high surface potential is not always the best way to maximize output power.