Kedar Deshmukh - Academia.edu (original) (raw)
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Papers by Kedar Deshmukh
2008 13th International Symposium on Electrets, 2008
Printing processes like gravure and off-set are being developed for flexible logic circuits. Diff... more Printing processes like gravure and off-set are being developed for flexible logic circuits. Different devices with consistent properties are needed in single circuits. This can be achieved by embedding preset, tuning charges in the Organic Field Effect Transistor (OFET) gate dielectric. If desired, contrasting characteristics can be obtained for different devices in the same way. This reduces the number of steps involved in the printing process and makes the process more energy efficient. In this article we show shifting of threshold voltage by charging with a Scanning Electron Microscope (SEM) electron source. Writing specific amounts of charge on the dielectric and a corresponding shift in threshold voltage is seen. The sample preparation will be discussed in detail elsewhere.
Organic Electronics, 2010
We report on the successful fabrication of full-swing charged organic inverter circuits by means ... more We report on the successful fabrication of full-swing charged organic inverter circuits by means of continuous mass-printing technologies. Using an electrostatic charged perfluorinated gate dielectric (Cytop TM), we demonstrate depletion-mode and enhancement-mode transistors with the same organic semiconductor in top-gate device structure. The threshold voltage of the printed p-type transistors can be shifted by injecting stable positive charges by means of a corona discharge or contact charging.
Journal of Power Sources, 2006
A borohydride fuel cell has been constructed using a platinized multiwalled carbon nanotube (MWCN... more A borohydride fuel cell has been constructed using a platinized multiwalled carbon nanotube (MWCNT) anode and an air cathode having an anionic exchange membrane separating the anode and cathode. The MWCNT was functionalized with carboxylic acid under nitric acid reflux. Platinum metal was subsequently incorporated into it by galvanostatic deposition. The platinized functionalized MWCNT was characterized by thermogravimetric analysis, Fourier transform infrared spectrum, scanning electron microscope and X-ray diffraction. The fuel cell produced a voltage of 0.95 V at low currents and a maximum power density of 44 mW cm −2 at room temperature in 10% sodium borohydride in a 4 M sodium hydroxide medium. Another borohydride fuel cell under identical conditions using carbon as the anode produced a cell voltage of 0.90 V and power density of about 20 mW cm −2. The improved performance of the MWCNT is attributed to the higher effective surface area and catalytic activity.
Applied Physics Letters, 2009
We report organic field-effect transistors (OFETs) with the hydrophobic gate dielectric exposed t... more We report organic field-effect transistors (OFETs) with the hydrophobic gate dielectric exposed to an electron beam before semiconductor deposition, shifting the threshold voltage toward positive gate bias for a p-channel semiconductor. A 1 μm Cytop film was irradiated with defined doses of electron beams with different energies. The charges/polarizations embedded in the dielectric by the irradiation have effective charge densities of ∼10−8 C/cm2. OFETs were completed using 5,5′-bis(4-hexylphenyl)-2,2′-bithiophene as the semiconductor, and showed corresponding shifts in Vth. Other OFETs were made where the gate dielectric was treated with a corona discharge. Both types of devices showed similar shifts in Vth and transfer characteristics. There is no change in mobility of the charge carriers after either charging process. The charges do not contribute to the gate capacitance but induce changes in the onset of capacitance increase caused by accumulation of mobile channel charge during...
Solar Energy, 2017
Non-fullerene acceptors have attracted great attention as an alternative to fullerene derivatives... more Non-fullerene acceptors have attracted great attention as an alternative to fullerene derivatives to overcome their disadvantages such as limited molecular design due to fullerene moiety, electronic tuning via structural modification, and weak absorption in the visible range. In this work, we design a new class of naphthalenediimide (NDI)-based small molecule acceptors by introducing an NDI central core unit and AD A -D-A-type moiety. The NDI-TR is a promising material as an electron acceptor for OSCs because of many advantages including high electron affinity and electron mobility, and well-matched energy levels with polymer donors. The device based on NDI-TR had the highest fill factor (0.69) and power conversion efficiency (3.07%) among fullerene-free organic solar cells with NDI small molecule acceptors. This high device efficiency may be attributed to improved charge transport and minimized bimolecular recombination due to the smooth surface roughness and pronounced face-on orientation of polymer backbones in the bulk heterojunction film.
2008 13th International Symposium on Electrets, 2008
Printing processes like gravure and off-set are being developed for flexible logic circuits. Diff... more Printing processes like gravure and off-set are being developed for flexible logic circuits. Different devices with consistent properties are needed in single circuits. This can be achieved by embedding preset, tuning charges in the Organic Field Effect Transistor (OFET) gate dielectric. If desired, contrasting characteristics can be obtained for different devices in the same way. This reduces the number of steps involved in the printing process and makes the process more energy efficient. In this article we show shifting of threshold voltage by charging with a Scanning Electron Microscope (SEM) electron source. Writing specific amounts of charge on the dielectric and a corresponding shift in threshold voltage is seen. The sample preparation will be discussed in detail elsewhere.
Organic Electronics, 2010
We report on the successful fabrication of full-swing charged organic inverter circuits by means ... more We report on the successful fabrication of full-swing charged organic inverter circuits by means of continuous mass-printing technologies. Using an electrostatic charged perfluorinated gate dielectric (Cytop TM), we demonstrate depletion-mode and enhancement-mode transistors with the same organic semiconductor in top-gate device structure. The threshold voltage of the printed p-type transistors can be shifted by injecting stable positive charges by means of a corona discharge or contact charging.
Journal of Power Sources, 2006
A borohydride fuel cell has been constructed using a platinized multiwalled carbon nanotube (MWCN... more A borohydride fuel cell has been constructed using a platinized multiwalled carbon nanotube (MWCNT) anode and an air cathode having an anionic exchange membrane separating the anode and cathode. The MWCNT was functionalized with carboxylic acid under nitric acid reflux. Platinum metal was subsequently incorporated into it by galvanostatic deposition. The platinized functionalized MWCNT was characterized by thermogravimetric analysis, Fourier transform infrared spectrum, scanning electron microscope and X-ray diffraction. The fuel cell produced a voltage of 0.95 V at low currents and a maximum power density of 44 mW cm −2 at room temperature in 10% sodium borohydride in a 4 M sodium hydroxide medium. Another borohydride fuel cell under identical conditions using carbon as the anode produced a cell voltage of 0.90 V and power density of about 20 mW cm −2. The improved performance of the MWCNT is attributed to the higher effective surface area and catalytic activity.
Applied Physics Letters, 2009
We report organic field-effect transistors (OFETs) with the hydrophobic gate dielectric exposed t... more We report organic field-effect transistors (OFETs) with the hydrophobic gate dielectric exposed to an electron beam before semiconductor deposition, shifting the threshold voltage toward positive gate bias for a p-channel semiconductor. A 1 μm Cytop film was irradiated with defined doses of electron beams with different energies. The charges/polarizations embedded in the dielectric by the irradiation have effective charge densities of ∼10−8 C/cm2. OFETs were completed using 5,5′-bis(4-hexylphenyl)-2,2′-bithiophene as the semiconductor, and showed corresponding shifts in Vth. Other OFETs were made where the gate dielectric was treated with a corona discharge. Both types of devices showed similar shifts in Vth and transfer characteristics. There is no change in mobility of the charge carriers after either charging process. The charges do not contribute to the gate capacitance but induce changes in the onset of capacitance increase caused by accumulation of mobile channel charge during...
Solar Energy, 2017
Non-fullerene acceptors have attracted great attention as an alternative to fullerene derivatives... more Non-fullerene acceptors have attracted great attention as an alternative to fullerene derivatives to overcome their disadvantages such as limited molecular design due to fullerene moiety, electronic tuning via structural modification, and weak absorption in the visible range. In this work, we design a new class of naphthalenediimide (NDI)-based small molecule acceptors by introducing an NDI central core unit and AD A -D-A-type moiety. The NDI-TR is a promising material as an electron acceptor for OSCs because of many advantages including high electron affinity and electron mobility, and well-matched energy levels with polymer donors. The device based on NDI-TR had the highest fill factor (0.69) and power conversion efficiency (3.07%) among fullerene-free organic solar cells with NDI small molecule acceptors. This high device efficiency may be attributed to improved charge transport and minimized bimolecular recombination due to the smooth surface roughness and pronounced face-on orientation of polymer backbones in the bulk heterojunction film.