Sub-micron phase coexistence in small-molecule organic thin films revealed by infrared nano-imaging
نویسندگان
چکیده
Controlling the domain size and degree of crystallization in organic films is highly important for electronic applications such as organic photovoltaics, but suitable nanoscale mapping is very difficult. Here we apply infrared-spectroscopic nano-imaging to directly determine the local crystallinity of organic thin films with 20-nm resolution. We find that state-of-the-art pentacene films (grown on SiO2 at elevated temperature) are structurally not homogeneous but exhibit two interpenetrating phases at sub-micrometre scale, documented by a shifted vibrational resonance. We observe bulk-phase nucleation of distinct ellipsoidal shape within the dominant pentacene thin-film phase and also further growth during storage. A faint topographical contrast as well as X-ray analysis corroborates our interpretation. As bulk-phase nucleation obstructs carrier percolation paths within the thin-film phase, hitherto uncontrolled structural inhomogeneity might have caused conflicting reports about pentacene carrier mobility. Infrared-spectroscopic nano-imaging of nanoscale polymorphism should have many applications ranging from organic nanocomposites to geologic minerals.
منابع مشابه
Synthesis, Characterization, and Application of Zr,Ce-TiO2/SiO2 Nanocomposite Thin Film as Visible-light Active Photocatalyst
A novel Zr,Ce-TiO2/SiO2 nanocomposite thin film was successfully prepared with various amounts of Zr4+ and Ce4+ as codopant ions for self-cleaning applications. A thin film was coated on a tile substrate by dip-coating and porous Zr,Ce-TiO2/SiO2 was obtained after heat treatment for 2 hours at 500 °C. The SEM images an...
متن کاملFabrication of Nb/V co-doped TiO2 thin films and study of structural, optical and photocatalytic properties
In this study, different samples of Niobium and Vanadium co-doped titania thin films (5-10-15 mol% Nb and 5-10-15 mol% V) were prepared via sol−gel dip coating method, using niobium chloride as niobium precursor, ammonium metavanadate as vanadium precursor, and titanium (IV) butoxide (TBT) as titanium precursor. The effects of doping amount on the structural, optical, and photo-catalytic prope...
متن کاملFabrication of Nb/V co-doped TiO2 thin films and study of structural, optical and photocatalytic properties
In this study, different samples of Niobium and Vanadium co-doped titania thin films (5-10-15 mol% Nb and 5-10-15 mol% V) were prepared via sol−gel dip coating method, using niobium chloride as niobium precursor, ammonium metavanadate as vanadium precursor, and titanium (IV) butoxide (TBT) as titanium precursor. The effects of doping amount on the structural, optical, and photo-catalytic prope...
متن کاملMechanical Properties and Microstructural Evolution of Ta/TaNx Double Layer Thin Films Deposited by Magnetron Sputtering
Crystalline tantalum thin films of about 500nm thickness were deposited on AISI 316L stainless steel substrate using magnetron sputtering. To investigate the nano-mechanical properties of tantalum films, deposition was performed at two temperatures (25°C and 200°C) on TaNx intermediate layer with different N2/Ar flow rate ratio from 0 to 30%. Nano-indentation was performed to obtain the mechani...
متن کاملEnhanced Photocatalytic Activity of Sol-Gel Derived Coral-like TiO2 Nanostructured Thin Film
To enhance photocatalytic degradation of organic pollutants, coral-like TiO2 nanostructured thin films were chemically synthesized through the sol-gel method. The fabricated thin films were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), nitrogen sorption isotherms, mercury porosimetry measurements, and UV-Vis Diffuse Reflectance Spectrum (DRS). The ...
متن کامل