ION MODULATED ORGANIC TRANSISTORS - Doria

Nikolai Kaihovirta2. EXPERIMENTALIn Paper 4, the I-V characterization of the PTFE:PFSA, at constantpolarity (DC), was done both in ambient air and in a nitrogen glovebox.25 nm thick gold electrodes were evaporated in vacuum, through ashadow mask. For the measurements through the membrane, theelectrode area was set to 0.5 cm 2 , while on the membrane the channelwidth was 1.0 cm and the channel length 1.0 mm.For the impedance spectroscopy measurements in Paper 4,approximately 30 nm thick gold electrodes (surface area 0.5 cm 2 ) wereevaporated in vacuum on both sides of the membrane. The sample wasplaced in an aluminum chamber and the chamber was vacuum pumpedto a level of 10 -3 – 10 -4 mbar in which the measurements were done. Theimpedance spectroscopy measurements were carried out using a GamryReference 600 potentiostat (Gamry Instruments). The potentiostat wasconnected to a computer and controlled by suitable software. The ACamplitude was 15 mV and the frequency ranged from 1 MHz to 1 Hzwith 10 points per decade. C i was calculated from the obtained reactancevalues.2.2.2 Optical CharacterizationIn Paper 5, the optical UV-Vis absorption analyses were performed in airwith a Hitachi U-3200 Spectrophotometer (Hitachi High-TechnologiesCorp.) connected to a computer. The step length was set to 2 nm. Duringthe thermal stress the samples were removed from the hotplate andallowed to cool down to room temperature prior to scanning.In Paper 4, the optical transmission through thegold/PTFE:PFSA/P3HT/gold structures were measured in air. Anincandescent tungsten lamp with a 435 nm cutoff filter was used as probelight. The light was focused on a 0.5 × 0.5 cm 2 area on the contact of thedevice, and the transmitted light was collected and focused into aSpectraPro 300i monochromator (Acton Research Corp.). Themonochromated light was then measured using a Si-detector, apreamplifier and a SR830 lock-in amplifier (Stanford Research Systems,Inc.). The instruments were controlled with LabView software. Forspectral measurements a wavelength range of 450 – 850 nm was used,and this range was scanned for applied voltages ranging from +2 V to -3Von the gate electrode. The voltage was applied for three minutes in orderto allow the sample to reach equilibrium. In Paper 4, the transmission wasmonitored at the optical absorption region by continuously scanningfrom 540 nm to 550 nm with no pauses and simultaneously applying asequence of voltages.19