Liquid‐polymer films sandwiched between two electrodes develop a surface instability caused by the electric field, giving rise to polymer structures that span the two plates. This study investigates the development of the resulting polymer morphologies as a function of time. The initial phase of the structure formation process is a sinusoidal surface undulation, irrespective of the sample parameters. The later stages of pattern formation depend on the relative amount of polymer in the capacitor gap (filling ratio). For high enough filling ratios, the final morphology of the pattern is determined by the partial coalescence of the initial pattern. The introduction of lateral‐field heterogeneities influences the initial pattern formation, with columns nucleated at locations of highest electric field (isolated points or edges). The subsequently formed secondary columns have higher degree of lateral symmetry compared to the pattern formed in a homogeneous field. The nucleation of individual columns or plugs also dominates the pattern formation in the presence of an electrode consisting of an array of lines. The results of this study therefore allow us to draw the conclusion that the accurate replication of structured electrodes typically proceeds by the initial nucleation of individual columns, followed by a coalescence process that yields the polymer replica.

We report the experimental observation of a morphological instability of a confined polymerair double layer sandwiched between two plates set to different temperatures. The homogeneous temperature gradient across the double layer causes the breakup of the polymer film into columns or stripes spanning the two plates. Experimentally, the characteristic wavelength of these patterns varies with the inverse of the initial heat flux through the bilayer. To gain insight into the nature of the instability, we have developed a phenomenological model that describes the heat flow in terms of diffusion through the bilayer. In an idealized microscopic model for the heat flow through the bilayer system, thermal modes in the polymer film with wavelengths ranging from the film thickness to the Debye limit contribute to the heat flux. The low end of this frequency spectrum causes a thermal radiation pressure at the polymer-air surface that destabilizes the film, while the high-frequency modes ascertain the heat conduction through the bilayer.

A capillary surface instability caused by a high temperature gradient is used to replicate sub‐micrometer patterns (see Figure for an example). As opposed to convection effects, the film instability is driven by the diffusion of heat across the polymer film. By lateral modulation of the temperature gradient, this instability can be harnessed as a lithographic technique.

The experimental observation of electric‐field‐induced instabilities of polymer films exposed to toluene vapors is reported. When using a laterally structured electrode, the pattern that forms in the polymer film is governed by the interplay of the intrinsic film instability and the periodicity of the electrode structure. By adjusting the applied voltage, it is possible to switch between two different pattern‐replication modes. A further important parameter is the aspect ratio of the structured electrode. For high ratios of polymer film thickness to capacitor‐plate spacing, structures with hierarchical length scales have been observed.

We report the experimental observation and a theoretical model for a thin-film instability caused by a temperature gradient. A polymer-air double layer sandwiched between two plates set to different temperatures shows an instability leading to polymer columns or stripes spanning the two plates. The characteristic wavelength of these patterns scales inversely with the initial heat flux through the double layer. Theoretically, we describe the heat flow in terms of the diffusion of heat through the bilayer, causing an interfacial radiation pressure that destabilizes the film.

The dewetting of a polymer film in a confined geometry was employed in a pattern-replication process. The instability of dewetting films is pinned by a structured confining surface, thereby replicating its topographic pattern. Depending on the surface energy of the confining surface, two different replication mechanisms were found, leading to a choice of either a negative or a positive replication mechanism of a patterned plate.

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We demonstrate the feasibility of white organic light-emitting diodes that exclude the transparent conductor indium-tinoxide. Instead, a highly conductive Orgacon™ PEDOT:PSS material in combination with a metal support structure is used as transparent anode and hole-injection layer. The PEDOT:PSS exhibits a conductivity of 460±20 S/cm and a work function of 5.35±0.05 eV. On ITO-free OLEDs on glass with an active area of ~6 cm ² the inclusion of 120 nm thick printed metal lines reduces the variation in brightness from 35% to 20%. The ITO-free concept based on PEDOT:PSS with printed metal structures is scaled up to large flexible OLEDs with a size of 150 cm 2 on a heat-stabilized Teonex® Polyethylene Naphtalate foil. The voltage distribution across the various electrodes was verified by a finite element model, allowing a prediction of the OLED brightness and homogeneity over large areas.