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- 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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- 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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- 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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- Chen, Miaoxiang, 1962-, et al.
(författare)
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High carrier mobility in low band gap polymer-based field-effect transistors
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:25, s. 252105-1-252105-3
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Tidskriftsartikel (refereegranskat)abstract
- A conjugated polymer with a low band gap of 1.21 eV, i.e., absorbing infrared light, is demonstrated as active material in field-effect transistors (FETs). The material consists of alternating fluorene units and low band gap segments with electron donor-acceptor-donor units composed of two electron-donating thiophene rings attached on both sides of a thiadiazolo-quinoxaline electron-acceptor group. The polymer is solution-processable and air-stable; the resulting FETs exhibit typical p-channel characteristics and field-effect mobility of 0.03 cm2 V−1 s−1.
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