Dektak profilometer

Structural characterization was performed on the films to determine their crystallinity using a Rigaku powder X-Ray diffractometer. The thickness of the films was measured using a Bruker Dektak profilometer. The films were characterized for their electrical properties to determine the dependence of resistance with temperature using a linear four-point probe configuration using a Keithley 6220 current source meter and a dual channel Keithley 2182 A nano-voltmeter which measured the voltage as well as the temperature of the films which was provided using a PID controlled oven. The data obtained from the linear four probe measurement was analyzed to determine the transition temperature of the films using MATLAB. The resistive heating effect on the films was measured using a FLIR 320 infra-red camera with the voltage being supplied using a HP E3633A DC power supply. The films were characterized to test for the transmission of UV, visible and near IR region using a Perkin Elmer Lambda 950 UV/Visible spectrometer. Voltage as well as temperature dependent transmission measurements were carried out on the films grown in the S-2 configuration, using the AZO layer to heat up the films.

Contact angles were measured by dropping 50 μl of test solvent onto the characterized surfaces and taking a photograph from a horizontally aligned position. The precise angles were measured using ImageJ with a plugin developed and provided by the Biomedical Imaging Group of the Ecole Polytechnique Federale de Lausanne.[33 (link)] The thicknesses and surface morphologies of the prepared thin films were characterized by a Dektak profilometer (Bruker, Billerica, MA, USA) and atomic force microscope (AFM) respectively. Grazing-incident X-ray diffraction (GI-XRD) measurements were performed at the X-ray diffraction beamline 5.2 at the Synchrotron Radiation Facility Elettra in Trieste (Italy). Two-dimensional diffraction patterns were recorded with a 2 M Pilatus silicon pixel X-ray detector (DECTRIS Ltd, Baden, Switzerland). The sample inclination to the beam was changed from ω = 0.03° to ω = 0.2° to characterize the surface (5 nm depth) and bulk properties of the samples, respectively. Detailed measurement conditions and data treatment can be found in a previously published work.[34 (link)]

P3HT (91–94 % regioregular, Rieke Metals) was dissolved in chlorobenzene (VWR chemicals) with a concentration of 0.15 mol l⁻¹ and spin-coated (70–80 nm) on ZnSe/Pt crystal and glass/ITO (15 Ω sq⁻¹, Xinyan), respectively. Quinacridone (TCI) was purified by repeated temperature gradient sublimation and vacuum-evaporated (90–100 nm) on both substrates mentioned before. Subsequently, a thin layer (≈40 nm) of PVA (99+ % hydrolyzed, Aldrich) solution, 7 mg PVA dissolved in 1 mL deionized water, was spin-coated (900 rpm; 3 seconds) onto the pigment and polymer, respectively, and finally dried under air. The thickness of the PVA layer was measured by a Dektak profilometer (Bruker). This treatment protects solid films from dissolving during electrochemical studies.