Strongly Enhanced Thermal Stability of Crystalline Organic Thin Films Induced by Aluminum Oxide Capping Layers

Abstract

enhancement of polymer-side-chain mobility at room temperature, and the saturation dose is largely dependent on film thickness. We also show that polymer rewriteability is directly correlated to the degree of photobleaching that occurs during writing. The very large birefringence and high optical transparency in the 650±1600 nm wavelength range is quite promising for integrated photonic device applications of photoaddressable polymer thin films. ExperimentalSample Preparation: Amorphous isotropic polymer films with thicknesses ranging from 160±780 nm were prepared by spinning PAP solutions in tetrahydrofuran on glass substrates. The sample thickness was determined with an Alpha-Step surface profiler, while the refractive index was measured with a spectroscopic ellipsometer.Optical Characterization: Film birefringence was quantified in situ using a standard experimental setup [7] where the reading source (633 nm HeNe or 670 nm diode) was polarized 45 with respect to the write source (488 nm line of the Ar + beam). Both beams are directed onto the sample surface in normal incidence (write diameter 1.4 mm, read diameter~0.5 mm), and subsequently pass through polarized beam splitters. The write beam and the perpendicular-polarized component of the read beam are then directed to germanium photodetectors to obtain intensity data for the calculation of photobleaching and birefringence, respectively.

Organic–Organic Heterostructures: Concepts and Applications

“…We note that a similar (and indeed much stronger) effect of shift of the melting/sublimation point was also observed for organic semiconductors (DIP), but under an aluminiumoxide (i.e. inorganic) capping layer, [87] which might be used in applications to enhance the temperature stability.…”

Organic Electronic Devices and Their Functional Interfaces

“…As already mentioned above, postdeposition annealing of organic thin films can significantly increase both crystallinity and the size of crystalline grains; importantly, this can be realized for small-molecular materials and polymer thin films. [156,157,162,170] 4. Organic Thin-Film Transistors (OTFTs)…”

“…[155] The importance of a temperature-stable capping layer (e.g. metal or metal oxide) for morphology-preserving postgrowth annealing of organic thin films was pointed out earlier by Peumans et al [156] and Sellner et al, [157] who showed that using such a layer can effectively suppress substantial surface roughening during annealing or early evaporation of an organic molecular compound. Furthermore, for the prototypical material pair-copper phthalocyanine (CuPc) and 3,4,9,10-perylene tetracarboxylic bis-benzimidazole (PTCBI)-annealing increased the size of bulk heterojunction grains and crystallinity, and such OPVCs exhibited conversion efficiencies of up to 1.4 %.…”

Real-time X-ray diffraction measurements of structural dynamics and polymorphism in diindenoperylene growth

“…Thin DIP films have been found to exhibit high structural order [10] but also rapid roughening after initial layer-by-layer growth [11][12][13]. Encapsulation of DIP thin films has been employed for increased device stability [14,15], and contact formation as well as electronic structure at contacts [16][17][18][19][20] have been studied. Its molecular orientation on insulators [12,21] and metals [20,22,23] has been measured, and high-resolution transmission electron microscopy (TEM) [24] and scanning tunneling microscopy (STM) [25] images give insight into the molecular arrangement.…”