| 1. |
- Muhammad, Riaz, et al.
(författare)
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The impact of ion irradiation on morphology, structure and optical properties of ZnO nanowires
- 2008
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Chemically grown ZnO nanowires were irradiated with ions and subsequently investigated by continues wave (cw) photoluminescence (PL) and time resolved PL (TRPL) both at room (300 K) and low (10 K) temperatures, and was compared with the as-grown samples. The ion bombardment was done by using 30 keV argon, and 40 MeV iodine ions using ion fluencies of 3 ×1016 ions/cm2, and 1.3 ×1013 ions/cm2, respectively. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) spectra showed that the morphology and structure of the ion irradiated ZnO nanowires were less damaged. Using the PL and XRD spectra the induced compressive strains in the irradiated samples was calculated. Also there was a decrease and increase in the XRD intensity which had emphasized that some texture modification occurred in the irradiated samples. No severe decomposition of the irradiated samples was observed. The PL measurements showed that the intensity of the near band emission (free exciton) of the irradiated ZnO nanowires was decreased for all irradiating ions, whereas the deep emission band was enhanced for iodine ions and suppressed for argon ions irradiated samples. A blue peak shift (~ 2 meV) of the excitonic emission of the irradiated samples was observed. The TRPL spectra for the as-grown and the irradiated ZnO nanowires were fitted with single and two components time decay constant, respectively.
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| 2. |
- Wang, Nan, et al.
(författare)
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Vertically Aligned Graphene-based Thermal Interface Material with High Thermal Conductivity
- 2018
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Ingår i: THERMINIC 2018 - 24th International Workshop on Thermal Investigations of ICs and Systems, Proceedings. - 9781538667590 ; , s. 285-288
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Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Here, a novel highly thermal conductive and lightweight graphene based thermal interface materials (GT) was developed for thermal management in power devices. Composed by vertically graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. The highest through-plane thermal conductivity GTs reaches to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium by over ten times. In addition, a thin layer of indium metal that coated on the surface of GTs can easily form alloys with many other metals at a relatively low reflow temperature. Therefore, GTs, as an excellent TIM, can provide complete physical contact between two surfaces with minimized the contact resistance. The measured total thermal resistance and effective thermal conductivity by using 300 mu m thick GTs as TIM between two copper blocks reaches to similar to 3.7 Kmm(2)/W and similar to 90 W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show even better thermal performance than pure indium bonding. In addition, GTs has more advantages than pure indium bonding, including low weight (density < 2 g/cm(3)), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues in form-factor driven electronics and other high power driven systems.
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| 3. |
- Andersson, Peter, et al.
(författare)
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Active Matrix Displays Based on All-Organic Electrochemical Smart Pixels Printed on Paper
- 2002
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Ingår i: Advanced Materials. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 14:20, s. 1460-1464
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Tidskriftsartikel (refereegranskat)abstract
- An organic electronic paper display technology (see Figure and also inside front cover) is presented. The electrochromic display cell together with the addressing electrochemical transistor form simple smart pixels that are included in matrix displays, which are achieved on coated cellulose-based paper using printing techniques. The ion-electronic technology presented offers an opportunity to extend existing use of ordinary paper.
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| 4. |
- Andersson, Peter, et al.
(författare)
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Organic Electrochemical Smart Pixels
- 2003
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Ingår i: Materials Research Society Symposium Proceedings. ; , s. D6.6-
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Konferensbidrag (refereegranskat)
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| 5. |
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| 6. |
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| 7. |
- Berggren, Magnus, et al.
(författare)
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Polymer based electrochemical devices for logic functions and paper displays
- 2003
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Here, we report on devices based on patterned thin films of the conducting polymer system poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulphonic acid) (PEDOT:PSS) combined with patterns of solid electrolyte. The key device functionalities base on the updating of the RedOx state of PEDOT. This results in control of the electronic properties of this conjugated polymer, i.e. the conductivity and optical properties are updated. Based on this we have achieved electric current rectifiers, transistors and display cells. Also, matrix addressed displays will be presented. Electrochemical switching is taking place when the oxidation and reduction potentials are overcome respectively. Therefore, these devices operate at voltage levels less then 2 Volts. Low voltage operation is achieved in devices not requiring any extremely narrow dimensions, as is the case for field effect driven devices. All devices reported can or has been made using standard printing techniques on flexible carriers.
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| 8. |
- Chen, Miaoxiang, 1962-, et al.
(författare)
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1 micron wavelength photo- and electroluminescence from a conjugated polymer
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:18, s. 3570-3572
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Tidskriftsartikel (refereegranskat)abstract
- We report photo- and electroluminescence from an alternating conjugated polymer consisting of fluorene units and low-band gap donor-acceptor-donor (D-A-D) units. The D-A-D segment includes two electron-donating thiophene rings combined with a thiadiazolo-quinoxaline unit, which is electron withdrawing to its nature. The resulting polymer is conjugated and has a band gap of 1.27 eV. The corresponding electro- and photoluminescence spectra both peak at approximately 1 mum. Light-emitting diodes, based on a single layer of the polymer, demonstrated external quantum efficiencies from 0.03% to 0.05%.
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| 9. |
- Chen, Miaoxiang, 1962-, et al.
(författare)
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Electric current rectification by an all-organic electrochemical device
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81, s. 2011-2013
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Tidskriftsartikel (refereegranskat)abstract
- An all-organic printed electrochemical rectifier is reported. The device is based on a patterned layer of poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) that interfaces a patterned electrolyte top layer. Overlap between the electrolyte layer and the conducting polymer pattern results in the formation of two electrochemically active areas within the conducting polymer pattern. When bias voltage is applied across the conducting polymer pattern, the PEDOT in the negatively biased areas is reduced electrochemically, while the PEDOT in the positively biased area is further oxidized. Reducing PEDOT from its p-doped, pristine state to the neutral state results in a marked loss of electrical conductivity. Due to the unsymmetrical device geometry, the current through the device may be shut off for one polarity of applied bias voltage with an electrical current rectification ratio of 100 compared to the opposite polarity. The output characteristics of a corresponding half wave rectifier as well as those from a full wave bridge rectifier show stable performance at frequencies below 15 Hz.
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| 10. |
- Chen, Miaoxiang, 1962-
(författare)
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Electrochemical and electronic devices based on low bandgap polymers
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The research field of the organic electronics includes light emitting diodes (OLEDs), field-effect transistors (OFETs), polymer photovoltaic cells (PVCs), polymer lasers and electrochemical devices. Recently, organic materials are envisaged for spintronics. This dissertation covers a large research scope ranging from electrochemical devices, light emitting diodes, to field-effect transistors, in both processing techniques and device characterizations.Printed all-organic electrochemical diodes and transistors on flexible plastic or paper substrates have been realized by simple and low-cost method of fabricating. Conducting polymer poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS), utilized as active component, is deposited by spin-coating or printing techniques. The devices are directly fabricated from design without the need for masks, patterns or dies. The output characteristics of both half-wave and full-wave rectifier circuits from two-terminal diodes show stable performances at frequencies of 5 Hz. Electrochemical transistors based on both three- and four-terminal configurations have good performances with IONlIoFF current ratios of 103 - 104 at operating voltages below 3 V. The new kind of devices reported are robust and could serve as components in microelectronics, and as redox sensors and detectors since the conductivity of conducting polymers depends on the redox states.Both LEDs and FETs are realized from a low bandgap donor-acceptor-donor (D-A-D) polymer. The polymer consists of fluorene units and donor-acceptor-donor (D-A-D) units. The D-A-D segment includes two electron-donating thiophene rings combined with a thiadiazolo-quinoxaline unit, which is electron withdrawing to its nature. The resulting polymer is conjugated and has a band gap of 1.27 eV. The corresponding electro- and photoluminescence spectra both peak at approximately 1 Ilm, which is largest emission wavelength ever reported to date. The resulting FETs exhibit typical p-channel functions, and relatively high field-effect mobility of 0.03 cm2y-1s-1, near zero threshold voltage and a current on/off ratio of 5 x104 in ambient atmosphere. The mobility value is highest in low bandgap D-A-D polymers ever reported so far.
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