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COE Main Report 2008

Har projektet följt planerna enligt ansökan, eller enligt senaste avstämning avseende:

  Tid: Ja

  Ekonomi: Ja

  Delresultat: Ja

  Projektdeltagare: Ja

Kommer planen att hålla kommande 6 mån avseende:

  Tid: Ja

  Ekonomi: Ja

  Delresultat: Ja

  Projektdeltagare: Ja

Sammanfattning av läget i projektet, delresultat och eventuella avvikelser från projektplanen

ONE Organic nanoelectronics

We demonstrated a micro-nano coupling device and method, to make possible patterning and addressing of crossbar nano matrices. We also demonstrated electrochemical transistors on nanowire format, with multiple nanowires contacting drain and source electrodes. These transistors are made from a novel derivative of PEDOT. Photoelectron spectroscopy has been used to study the self-charge-balancing PEDOT-derivative with particular emphasis on determining the counter ion species and the doping level.

Organic semiconductor blends are commonly used in organic based (opto-) electronic devices. They are composed of two types of (macro-) molecules, referred to as the guest and host. To achieve optimum device operation, the chemical nature, electronic structure, molecular order and the relative concentration of the guests and host are crucial. We have realized simulations of the current density versus the voltage (J–V) behavior of a two terminal device based on a variable-range hopping model in which the electronic states of the guest and host are represented by two Gaussian distributions. The J–V behavior is investigated for various energetic mismatches between guest and host states, widths of the distribution as well as the guest concentrations. A simple tool has been developed to enable an easy prediction of the J–V behavior of organic host–guest diodes is derived.

TWO –Printed electronics

A 7 segment display module, a pseudo watch, with shift register produced in an additive screen printing process was demonstrated. Transistors printed with inkjet methods were developed. Both of these used electrochemical transistors from PEDOT-PSS. In electrolyte gated organic field effect transistors faster response is possible.

Polyelectrolytes are promising materials as gate dielectrics in organic field-effect transistors (OFETs) as reported last year. Upon gate bias, their polarization induces an ionic charging current, which generates a large double layer capacitor (10–500 mF/ cm2) at the semiconductor/electrolyte interface. The resulting transistor operates at low voltages (<1V) and its conducting channel is formed in 50 microseconds. The effect of ionic currents on the performance of the OFETs is investigated by varying the relative humidity of the device ambience. Within defined humidity levels and potential values, the water electrolysis is negligible and the OFETs performances are optimum.

THREE Organic optoelectronics

A number of conjugated polymers with the same polymer backbone, but with different side chains, have been synthesized and evaluated in solar cells. Depending on the substituents on the polymers the morphology was different, which also affected the charge mobility. Most of the synthesized polymers within the project have also been (re)evaluated using electrochemistry under identical conditions.
We have also added polymers from a new class of alternating polyphenylenes, to extend coverage of the solar spectrum. With the recent publication of photovoltage 0.8 V at 900 nm absorption, we hold a world record.

Time resolved work on charge generation and recombination in APFO3-fullerenes has been completed and a paper is being submitted. With the help of three different fullerenes, the driving force for charge generation and recombination could be varied. The driving force effect on charge generation and recombination has been further studied in different polymer:fullerene blends where a series of low-band gap polymers were used. The most important result is that the rate of charge carrier recombination is directly correlated to solar cell efficiency, but it does not seem to be directly related to the driving force of electron transfer.

Extensive time resolved THz experiments on polymer:fullerene solar cell blends have been performed. We have been able to show that the charge carrier mobility is strongly time dependent and very much higher than the equilibrated mobility right after photogeneration of the charges. This has major implications for the modeling of materials.

Light trapping in solar cells with the help of microlenses has been demonstrated. Folded solar cells has been extensively modelled and optimized using optical simulations, both for tandem and single materials. Folded and flexible polymer solar cells on plastics has been assembled, and a new route to transparent solar cells demonstrated. The first photovoltaic device modules have been demonstrated, using series/parallel connections of individual devices. A simplified scheme for anode/cathode patterning has been developed for such modules.

Photoelectron spectroscopy in combination with DFT calculations have been used to study the energy level alignment at an organic donor/metal interface used to down shift the work function. Organic-organic and organic-metal interfaces in bulk heterojunction solar cells have been studied and optimized.

Publikationer, patent, nyttiggörande, mm under redovisade verksamhetsår

1. Andersson LM, Osikowicz W, Jakobsson FLE, Berggren M, Lindgren L, et al. 2008. Intrinsic and extrinsic influences on the temperature dependence of mobility in conjugated polymers. Organic Electronics 9: 569
2. Andersson V, Tvingstedt K, Inganas O. 2008. Optical modeling of a folded organic solar cell. Journal of Applied Physics 103
3. De S, Kesti T, Maiti M, Zhang F, Inganas O, et al. 2008. Exciton dynamics in alternating polyfluorene/fullerene blends. Chemical Physics 350: 14
4. Hamedi M, Herland A, Karlsson RH, Inganas O. 2008. Electrochemical devices made from conducting nanowire networks self-assembled from amyloid fibrils and alkoxysulfonate PEDOT. Nano Letters 8: 1736
5. Hamedi M, Herlogsson L, Crispin X, Marcilla R, Berggren M, Inganas O. 2009. Fiber-Embedded Electrolyte-Gated Field-Effect Transistors for e-Textiles. Advanced Materials 21: 573
6. Herlogsson L, Noh YY, Zhao N, Crispin X, Sirringhaus H, Berggren M. 2008. Downscaling of Organic Field-Effect Transistors with a Polyelectrolyte Gate Insulator. Advanced Materials 20: 4708
7. Hultell M, Stafstrom S. 2008. Nonradiative relaxation processes in molecular crystals. Journal of Luminescence 128: 2019
8. Hultell M, Stafstrom S. 2009. Impact of ring torsion dynamics on intrachain charge transport in conjugated polymers. Physical Review B 79
9. Jakobsson FLE, Crispin X, Berggren M. 2009. Prediction of the current versus voltage behavior of devices based on organic semiconductor guest-host systems. Organic Electronics 10: 95
10. Lindell L, Unge M, Osikowicz W, Stafstrom S, Salaneck WR, et al. 2008. Integer charge transfer at the tetrakis(dimethylamino)ethylene/Au interface. Applied Physics Letters 92: 3
11. Mannerbro R, Ranlof M, Robinson N, Forchheimer R. 2008. Inkjet printed electrochemical organic electronics. Synthetic Metals 158: 556
12. Nemec H, Nienhuys HK, Zhang F, Inganas O, Yartsev A, Sundstrom V. 2008. Charge carrier dynamics in alternating polyfluorene copolymer: Fullerene blends probed by terahertz spectroscopy. Journal of Physical Chemistry C 112: 6558
13. Said E, Larsson O, Berggren M, Crispin X. 2008. Effects of the Ionic Currents in Electrolyte-gated Organic Field-Effect Transistors. Advanced Functional Materials 18: 3529
14. Svensson PO , Nilsson D, Forchheimer R, Berggren M. 2008. A sensor circuit using reference-based conductance switching in organic electrochemical transistors. Applied Physics Letters 93
15. Tvingstedt K, Dal Zilio S, Inganas O, Tormen M. 2008. Trapping light with micro lenses in thin film organic photovoltaic cells. Optics Express 16: 21608
16. Zhang FL, Bijleveld J, Perzon E, Tvingstedt K, Barrau S, et al. 2008. High photovoltage achieved in low band gap polymer solar cells by adjusting energy levels of a polymer with the LUMOs of fullerene derivatives. Journal of Materials Chemistry 18: 5468
17. Zhou YH, Zhang FL, Tvingstedt K, Barrau S, Li FH, et al. 2008. Investigation on polymer anode design for flexible polymer solar cells. Applied Physics Letters 92
18. Zhou YH, Zhang FL, Tvingstedt K, Tian WJ, Inganas O. 2008. Multifolded polymer solar cells on flexible substrates. Applied Physics Letters 93

Patent application:
-SE 0802405-1: "Method for manufacturing a photovoltaic cell, a photovoltaic cell and a photovoltaic module" Tvingstedt, Inganäs

Övriga kommentarer
Only very small activities are now remaining within COE (at Chalmers) and most projects have been finalized. The continuation of COE activities through the new program OPEN ( including printed electronics and nanoelectronics) and through funding from Energimyndigheten(solar cells) allows continued production in the fields of organic electronics.

Eventuella styrgruppsmöten under året, datum
May 14, IFM, Linköping

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Last updated: 03/20/09