Organic Electronic Devices and Their Functional Interfaces

Abstract

A most appealing feature of the development of (opto)electronic devices based on conjugated organic materials is the highly visible link between fundamental research and technological advances. Improved understanding of organic material properties can often instantly be implemented in novel device architectures, which results in rapid progress in the performance and functionality of devices. An essential ingredient for this success is the strong interdisciplinary nature of the field of organic electronics, which brings together experts in chemistry, physics, and engineering, thus softening or even removing traditional boundaries between the disciplines. Naturally, a thorough comprehension of all properties of organic insulators, semiconductors, and conductors is the goal of current efforts. Furthermore, interfaces between dissimilar materials-organic/organic and organic/inorganic-are inherent in organic electronic devices. It has been recognized that these interfaces are a key for device function and efficiency, and detailed investigations of interface physics and chemistry are at the focus of research. Ultimately, a comprehensive understanding of phenomena at interfaces with organic materials will improve the rational design of highly functional organic electronic devices.

Copper-phthalocyanine based metal–organic interfaces: The effect of fluorination, the substrate, and its symmetry

“…37 Previous work reported the disappearance of the Au(111) herringbone reconstruction under the F 16 CuPc monolayers. 26 However, higher quality STM measurements have now proven the opposite, revealing the substrate reconstruction under the organic overlayer with an fcc/hcp periodicity measured along the [1][2][3][4][5][6][7][8][9][10] direction of 65 ± 3 Å, thus virtually unchanged with respect to the pristine Au(111). While this could be interpreted as the result of very weak molecule-substrate interactions, 31 the reported disappearance of the Au(111) surface state upon F 16 CuPc adsorption, as measured by valence band photoelectron spectroscopy, 26 still supports the picture of a significant interaction.…”

“…31,38 CuPc on Au(111) leads to the growth of crystalline layers characterized by a square unit cell of dimensions a = 13.9 ± 0.7 Å, and it hardly affects the underlying Au(111) surface reconstruction. 30,39 The unit cell vectors are directed along the high symmetry and [1][2][3][4][5][6][7][8][9][10] directions (Fig. 4).…”

“…1 The performance of these devices is particularly dependent on the properties of their various interfaces including the metal-organic interface between the contacts and the active semiconducting material. 3 A detailed knowledge of these interfaces is thus of paramount importance for the establishment of correlations between their properties and device performance, which could eventually allow a directed optimization of the devices via interface engineering. Among potential contact materials for optoelectronic devices we find, for example, Au and Cu.…”

Electrically driven photon antibunching from a single molecule at room temperature

“…In Figure 3a, the current density and the overall emission intensity of the OLED is plotted in dependence of the applied voltage. Onset of photon emission occurred above 5 V, which can be related to injection barriers at the respective contact interface 29 . Above this threshold, electron hole recombination takes place either on the polymer or dopant molecules reaching a maximum current density of up to 200 mA cm − 2 .…”

Redox-controlled potassium intercalation into two polyaromatic hydrocarbon solids

“…Bulk KxPentacene (x = 1, 2 and 3.6) has previously been reported without structural characterisation, [17][18][19] and metallic conductivity has been reported in potassium-doped pentacene thin films. [20][21][22][23][24] As pentacene is more readily available than picene, we chose initially to address the synthesis of potassium-intercalated pentacene samples suitable for structural analysis, before applying these protocols to the picene system. …”