| 1. |
- Andersson, Mattias, et al.
(författare)
-
Intrinsic and extrinsic influences on the temperature dependence of mobility in conjugated polymers
- 2008
-
Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 9:5, s. 569-574
-
Tidskriftsartikel (refereegranskat)abstract
- The temperature dependence of charge carrier mobility in conjugated polymers and their blends with fullerenes is investigated with different electrical methods, through field effect transistor (FET), space charge limited current (SCLC) and charge extraction (CELIV) measurements. Simple models, such as the Gaussian disorder model (GDM), are shown to accurately predict the temperature behavior, and a good correlation between the different measurement methods is obtained. Inconsistent charge carrier concentrations in the modeling are explained through intrinsic non-equilibrium effects, and are responsible for the limited applicability of existing numerical models. A severe extrinsic influence from water in FETs with a hydrophilic insulator interface is also demonstrated. The presence of water leads to a significant overestimate of the disorder in the materials from measurements close to room temperature and erratic behavior in the 150-350 K range. To circumvent this problem it is shown to be necessary to measure under ultra high vacuum (UHV) conditions. © 2008 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Jakobsson, Fredrik L.E. 1974-, et al.
(författare)
-
On the switching mechanism in Rose Bengal-based memory devices
- 2007
-
Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199. ; 8:5, s. 559 -565
-
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.
|
|
| 3. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Prediction of the current versus voltage behavior of devices based on organic semiconductor host-guest systems
- 2009
-
Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 10:1, s. 95-106
-
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.
|
|
| 4. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Towards addressable organic impedance switch devices
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:6
-
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.
|
|
| 5. |
- Jakobsson, Fredrik L. E., 1974-, et al.
(författare)
-
Towards all-plastic flexible light emitting diodes
- 2006
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 433:1-3, s. 110-114
-
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.
|
|
