| 1. |
- Jakobsson, Fredrik L.E. 1974-, et al.
(författare)
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On the switching mechanism in Rose Bengal-based memory devices
- 2007
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Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199. ; 8:5, s. 559 -565
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Tidskriftsartikel (refereegranskat)abstract
- Impedance switching has been observed in many organic devices, but the mechanism is still a matter of debate. Reliable switch devices consisting of an organic layer of Rose Bengal derivatives sandwiched in between indium tin oxide and aluminum electrodes were fabricated. Modifying the chemical nature of the organic layers and visualizing the temperature distribution in the organic memory rule out several mechanisms. It is shown that the memory effect originates from filamentary switching.
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| 2. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
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Prediction of the current versus voltage behavior of devices based on organic semiconductor host-guest systems
- 2009
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Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 10:1, s. 95-106
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Tidskriftsartikel (refereegranskat)abstract
- Organic semiconductor blends are commonly used in organic based (opto-)electronic devices. They are composed of two types of (macro-) molecules, referredto as the guest and host. To achieve optimum device operation, the chemicalnature, electronic structure, molecular order and the relative concentration of theguests and host are crucial. Here, we present simulation results of the currentdensity versus the voltage (J-V) behavior of a two-terminal device based on avariable-range hopping model in which the electronic states of the guest and hostare represented by two Gaussian distributions. The J-V behavior is investigatedfor various energetic mismatches between guest and host states, widths of thedistribution as well as the guest concentration. Finally, a simple tool enablingeasy prediction of the J-V behavior of organic host-guest diodes is derived.
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| 3. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Towards addressable organic impedance switch devices
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:6
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Tidskriftsartikel (refereegranskat)abstract
- The addressability of organic impedance switch devices as the memory elements of cross-point matrices is improved by introducing nonlinear behavior in their current-voltage characteristics. This is realized by adding a semiconducting layer of copper (II) phthalocyanine (CuPc) on top of the switch layer of Rose Bengal (RB) sodium salt. Leakage currents from unaddressed cells in a matrix are reduced by a factor of 17; thus improving the signal-to-background ratio, reducing driver currents and limiting the potential drop along the addressing lines. The matrix size of RB switch devices, using organic conductors, is predicted to be increased by 32 times when using the additional CuPc layer.
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| 4. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Towards all-plastic flexible light emitting diodes
- 2006
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 433:1-3, s. 110-114
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Tidskriftsartikel (refereegranskat)abstract
- All-plastic light emitting diodes require the design and fabrication of low work function plastic electrodes. Here, we show that the work function of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT-PSS) can be decreased from 4.8 eV to 3.9 eV by surface reaction with the strong electron-donor tetrakis(dimethylamino)ethylene (TDAE). The surface modification was characterized by photoelectron spectroscopy and optical spectroscopy. The low work function plastic electrode was used in a first prototype for all-plastic light emitting diodes.
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| 5. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Tuning the energy levels of photochromic diarylethene compounds for optoelectronic switch devices
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Photochromic diarylethene molecules (PC) is investigated for use in opticalwrite/electrical read memory applications. The frontier energy levels and dipolemoment is calculated using density functional theory. Good agreement is foundbetween calculated electronic structure and measured ultraviolet photoelectronspectra. The changes in frontier energy levels and dipole moment are scrutinizedupon two different approaches for chemical modification: (i) adding substituentsto the ethylene bridge; or (ii) changing the chemical nature of the aryl rings.Through the chemical modification the frontier energy levels can be tuned bymore than 2 eV. The calculated molecular properties are used in charge transportmodels to predict the behavior of devices based on these molecules. By using thePC in combination with an organic semiconductor (in bilayer or blend) goodswitching behavior can be achieved in a device. The switch effect is predicted tobe mainly due to switch in frontier energy levels rather than switch of dipolemoment. This is concluded since the dipole moment is either too small (< 5 D) orthe switch effect to small (less than a factor of two).
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