Formation of Al nanostructures on Alq3: An in situ grazing incidence small angle X-ray scattering study during radio frequency sputter deposition

6 pags., 4 figs., 1 sch.The formation of metal/organic interfaces is a complicated process involving chemical interaction, physical nucleation and diffusion, and thin film growth. It is closely related to the performance of organic electronic devices. To understand this process, we investigate the system of aluminum (Al) and tris(8-hydroxyquinolinato)aluminum (Alq3) as a model, owing to the well-known strong chemical interaction between both and their close technological relevance to organic light emitting devices. By using grazing small angle incidence X-ray scattering (GISAXS), we follow the Al thin film development on top of Alq3 during radio frequency (rf) sputter deposition in real-time and without interrupting the growth process. Three growth stages have been clearly distinguished: Al diffusion into Alq3, Al/Alq3 complex agglomeration and self-assembled Al pillar nanostructure thin film development. Thus in situ GISAXS yields the fundamental insights into the formation of the metal/organic interface for small organic semiconductor devices, prepared via vacuum based deposition techniques. © 2013 American Chemical Society.S.Y. acknowledges the Knut och Alice Wallenberg foundation for the kindfinancial support. P.M.-B., E.M., and K.S.acknowledge financial support by TUM.solar in the frame ofthe Bavarian Collaborative Research Project“Solar technologiesgo Hybrid′′(SolTec) and by the GreenTech Initiative(Interface Science for Photovoltaics - ISPV) of the EuroTechUniversities. Portions of this research were carried out at thelight source PETRA III at DESY, a member of the Helmholtz Association (HGF). Dr. David Babonneau is acknowledged forhelpful discussion, and Erik Braden for the XRR measurementsPeer reviewe

Monitoring Structural Dynamics of In-situ Spray-Deposited Zinc Oxide Films for Application in Dye-Sensitized Solar Cells

The spray-deposition technique is an effective and scalable method to deposit zinc oxide nanostructures, which are used as active layers for dye-sensitized solar cells (DSSCs) in the present study. The dynamics of structural evolution are studied with grazing incidence small-angle X-ray scattering during in situ spraying. Nanostructured films obtained through multiple spray shots provide suitable structural length scales, morphologies, and film thicknesses; this leads to reasonable performance in a DSSC with the highest short-circuit current density reported so far

Custom-Made Morphologies of ZnO Nanostructured Films Templated by a Poly(styrene-block-ethylene oxide) Diblock Copolymer Obtained by a Sol-Gel Technique

Zinc oxide (ZnO) nanostructured films are synthesized on silicon substrates to form different morphologies that consist of foamlike structures, wormlike aggregates, circular vesicles, and spherical granules. The synthesis involves a sol–gel mechanism coupled with an amphiphilic diblock copolymer poly(styrene-block-ethylene oxide), P(S-b-EO), which acts as a structure-directing template. The ZnO precursor zinc acetate dihydrate (ZAD) is incorporated into the poly(ethylene oxide) block. Different morphologies are obtained by adjusting the weight fractions of the solvents and ZAD. The sizes of the structure in solution for different sol–gels are probed by means of dynamic light scattering. Thin-film samples with ZnO nanostructures are prepared by spin coating and solution casting followed by a calcination step. On the basis of various selected combinations of weight fractions of the ingredients used, a ternary phase diagram is constructed to show the compositional boundaries of the investigated morphologies. The evolution and formation mechanisms of the morphologies are addressed in brief. The surface morphologies of the ZnO nanostructures are studied with SEM. The inner structures of the samples are probed by means of grazing incidence small-angle X-ray scattering to complement the SEM investigations. XRD measurements confirm the crystallization of the ZnO in the wurtzite phase upon calcination of the nanocomposite film in air. The optical properties of ZnO are analyzed by FTIR and UV/Vis spectroscopy

Investigation of morphological degradation of P3HT:PCBM bulk heterojunction films exposed to long-term host solvent vapor

Solution-based processing procedures are widely used during the fabrication of polymer solar cells both on the lab scale and in industrial applications. The understanding of device stability in its host solvent vapor atmosphere is of great significance to the fabrication, encapsulation and storage. Solar cells with poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) bulk heterojunction (BHJ) active layers are prepared with different solvents of chlorobenzene, toluene, xylene and dichlorobenzene. The stability is investigated via exposure to their respective host solvent vapor for a long period. All solar cells strongly degrade after exposure to solvent vapor for long-term and only the dichlorobenzene-related device still shows reasonable function. The morphology of P3HT:PCBM BHJ films is probed using optical microscopy, atomic force microscopy, grazing incidence small and wide angle X-ray scattering and absorption measurements. The solvent induced PCBM crystallization is identified as the main reason for device failure

A Quantitative Approach to Tune Metal Oxide Network Morphology based on Grazing-Incidence Small-Angle X-ray scattering Investigations

Based on a diblock copolymer-assisted sol-gel route, zinc oxide (ZnO) films with a foam-like network morphology are synthesized using zinc acetate dihydrate as a precursor. Poly(styrene-block-ethylene oxide) diblock copolymers with two different molecular weights are examined to compare the influence on the resulting morphologies. The variation in the porosity and in the pore size of the ZnO foam as a function of increasing amount of ZnO precursor are probed with grazing-incidence small-angle X-ray scattering (GISAXS). The GISAXS data are complemented with a surface topography investigation based on scanning electron microscopy. It is observed that the block copolymer template with the higher molecular weight yields a smaller average pore size and a lower average porosity of about 21%

Formation of Al Nanostructures on Alq3: An in Situ Grazing Incidence Small Angle X-ray Scattering Study during Radio Frequency Sputter Deposition

The formation of metal/organic interfaces is a complicated process involving chemical interaction, physical nucleation and diffusion, and thin film growth. It is closely related to the performance of organic electronic devices. To understand this process, we investigate the system of aluminum (Al) and tris(8-hydroxyquinolinato)- aluminum (Alq3) as a model, owing to the well-known strong chemical interaction between both and their close technological relevance to organic light emitting devices.By using grazing small angle incidence X-ray scattering (GISAXS), we follow the Al thin film development on top of Alq3 during radio frequency (rf) sputter deposition in real- time and without interrupting the growth process. Three growth stages have been clearly distinguished: Al diffusion into Alq3, Al/Alq3 complex agglomeration and self-assembled Al pillar nanostructure thin film development. Thus in situ GISAXS yields the fundamental insights into the formation of the metal/organic interface for small organic semiconductor devices, prepared via vacuum based deposition techniques

Formation of Al Nanostructures on Alq3: An in Situ Grazing Incidence Small Angle X‑ray Scattering Study during Radio Frequency Sputter Deposition

The formation of metal/organic interfaces is a complicated process involving chemical interaction, physical nucleation and diffusion, and thin film growth. It is closely related to the performance of organic electronic devices. To understand this process, we investigate the system of aluminum (Al) and tris­(8-hydroxyquinolinato)­aluminum (Alq3) as a model, owing to the well-known strong chemical interaction between both and their close technological relevance to organic light emitting devices. By using grazing small angle incidence X-ray scattering (GISAXS), we follow the Al thin film development on top of Alq3 during radio frequency (rf) sputter deposition in real-time and without interrupting the growth process. Three growth stages have been clearly distinguished: Al diffusion into Alq3, Al/Alq3 complex agglomeration and self-assembled Al pillar nanostructure thin film development. Thus in situ GISAXS yields the fundamental insights into the formation of the metal/organic interface for small organic semiconductor devices, prepared via vacuum based deposition techniques