From One‐ to Three‐Dimensional Organic Semiconductors: In Search of the Organic Silicon?

Abstract

Organic semiconductors based on π‐conjugated systems are the focus of considerable interest in the emerging area of soft or flexible photonics and electronics. Whereas in recent years the performances of devices such as organic light‐emitting diodes (OLEDs), organic field‐effect transistors (OFETs), or solar cells have undergone considerable progress, a number of technical and fundamental problems related to the low dimensionality of organic semiconductors based on linear π‐conjugated systems remain unsatisfactorily resolved. This low dimensionality results in an anisotropy of the optical and charge‐transport properties, which in turn implies a control of the material organization/molecular orientation during or after device fabrication. Such a constraint evidently represents a problem when device fabrication by solution‐based processes, such as printing techniques, is envisioned. The aim of this short Review is to illustrate possible alternative strategies based on the development of organic semiconductors with higher dimensionality, capable to exhibit isotropic electronic properties.

Solution‐Processed Bulk Heterojunction Photovoltaic Cells from Gradient π‐Conjugated Thienylene Vinylene Dendrimers

“…Such small shifts implied that intermolecular aggregation (usually observed for OTV derivatives in thin films) was, to a large extent, suppressed by the truxene moieties with hexyl substituents and the overall dendritic structure. [13,28] The band gaps of dendrimers were estimated from the onset of absorption spectra in thin films. G0-2-1 has a band gap of 2.43 eV and G0-4-2 has a band gap of 2.00 eV; these values are slightly larger than that of PTV (E g = 1.74 eV).…”

Design and Synthesis of Phosphorescent Iridium Containing Dendrimers for Potential Applications in Organic Light‐Emitting Diodes

“…[1][2][3][4] In addition, the oligomers can be designed to possess conjugated cores for efficient emission and/or charge transport and to have appropriate terminal groups and/or side chains for good processibility. This unique molecular architecture therefore allows independent optimization of the optoelectronic and processing properties.…”

“…4 ], (5% per C-Br bond), were added a degassed 2 M K 2 CO 3 aqueous solution (5 equiv.) and degassed toluene with a ratio of 1:2.…”

Photophysical Properties of Two New Donor-Acceptor Conjugated Copolymers and Their Model Compounds: Applications in Polymer Light Emitting Diodes (PLEDs) and Polymer Photovoltaic Cells (PPCs)

“…However, in these linear D-A polymers, the molecular interactions and packing orientation of the conjugating moieties need to be carefully controlled to ensure proper process ability and charge transporting properties [85]. A fundamental understanding of the ultimate relations between structure and properties of these materials is necessary for using them in photovoltaic cells.…”