Organic–Organic Heterostructures: Concepts and Applications

Abstract

We review basic concepts as well as recent examples and applications of organic-organic heterostructures. We organize the different types of heterostructures according to material A deposited on material B (A/B), A co-deposited with B (A:B), heterostructures in the monolayer regime including nanostructuring concepts and systems involving self-assembled monolayers, as well as various other architectures, including superlattices. While most examples are related to small-molecule organic semiconductors, many of the ideas can be applied to other systems. The central theme is growth and structure as well as optical and electronic properties. Finally, we comment on implications for device applications.

Electronic Structures of a Well-Defined Organic Hetero-Interface: C₆₀on Pentacene Single Crystal

“…Each target material, pentacene and C 60 , is respectively a representative p-and n-type organic semiconductor, and a combination of these is known to constitute one of the most proto-typical organic solar cell devices [12]. Interface formation of this couple is interesting also in terms of their distinct molecular symmetries, namely pentacene has a molecular shape of a uniaxial elongation whereas C 60 is of the spherical symmetry [13]. A number of experimental and theoretical studies so far addressed energetics and dynamics of the inter-molecular contact of these two materials [14][15][16][17][18][19][20].…”

Supramolecular heterostructures formed by sequential epitaxial deposition of two-dimensional hydrogen-bonded arrays

“…Specifically, the additional functional control, which may be achieved through the formation of heterostructures realized by placing one supramolecular layer on another and resulting in growth into the third dimension perpendicular to the substrate, has not been widely explored for these materials. Such additional control of material properties is well established for semiconductors, both organic [25][26][27][28][29][30] and inorganic 31 , and, more recently, layered materials 32 , providing a strong motivation to explore analogue materials derived from stacked supramolecular networks. Here we describe the successful formation of heterostructures formed by the sequential growth of distinct one-and two-dimensional arrays.…”

Structure and Morphology of Organic Semiconductor–Nanoparticle Hybrids Prepared by Soft Deposition

“…20 A thorough understanding of their growth and structure is prerequisite to the efficient implementation on a technological basis, since the morphology of OSCs has a strong impact on their charge carrier mobility and other physical properties. 1,[20][21][22][23][24][25][26][27][28][29][30] The basic understanding has largely remained on a qualitative level, since in most cases the film structure is not sufficiently well defined due to complex structural phenomena such as phase coexistence, changes in the molecular conformation or orientation, and morphological transitions. Thus there is the avid need to comprehend the different structural aspects of the hybrid structures like, e.g.…”