Lest We Forget–The Importance of Heteroatom Interactions in Heterocyclic Conjugated Systems, from Synthetic Metals to Organic Semiconductors

Abstract

The field of synthetic metals was, and remains, highly influential for the development of organic semiconductor materials. Yet, with the passing of time and the rapid development of conjugated materials in recent years, the link between synthetic metals and organic semiconductors is at risk of being forgotten. In this review, we reflect on one of the key concepts developed in synthetic metals – heteroatom interactions. The application of this strategy in recent organic semiconductor materials, small molecules and polymers, is highlighted, with analysis of X‐ray crystal structures and comparisons with model systems used to determine the influence of these non‐covalent short contacts. The case is made that the wide range of effective heteroatom interactions and the high performance that has been achieved in devices from organic solar cells to transistors is testament to the seeds sown by the synthetic metals research community.This article is protected by copyright. All rights reserved

Design Rules to Optimize the Intermolecular and Long-Range Packing of Organic Semiconductor Crystals

“…Intramolecular noncovalent interactions, such as heteroatom interactions and hydrogen bonds, play a significant role in the crystal engineering of OSCs and their properties. − While electrostatic interactions between sulfur and neighboring heteroatoms, like fluorine atoms within the same molecule or polymer chain, , are crucial, hydrogen bonding within conjugated polymers can exhibit even greater strength. − For the BDT-H trimer, there are no hydrogen bonds or F···S attractive interactions, only S···S repulsion between neighboring BDT rings (Scheme c). By comparison, in the anti-conformer of the BDT-F trimer, we observe S···F attractive interactions, while in the syn-configuration, we observe H-bond (H···F) attraction and S···S repulsion between neighboring BDTs (Scheme d).…”

Two‐Dimensional Conjugated Polymers: a New Choice For Organic Thin‐Film Transistors

“…[166] In addition, the NÀ H•••π bonding of the pyrrole unit and the NÀ H•••H bonding of the pyridine unit contribute to enhancing the charge carrier migration speed of 2DCPs. [167] These advantages make embedding nitrogen-containing heterocyclic units and oxygen-containing heterocyclic units into the framework of 2DCP highly promising. Through molecular structural design, the bandgap of 2DCPs can be more closely matched to the operating mechanism of OTFTs, manifested as merely zero excitation at non-gate voltage but sufficient charge accumulation when a gate voltage is applied.…”

Conformational Analysis of Conjugated Organic Materials: What Are My Heteroatoms Really Doing?

“…These heteroatoms naturally alter charge distribution within the polymers or small molecules, cause polarization of the covalent bonds, and influence structural properties of the material through inter-and intrachain non-covalent interactions. [6] It is perhaps the non-covalent interactions which have attracted the greatest attention in OSC molecular design, [7,8] many materials seemingly involving heteroatoms in the search of "conformational locks" and planarized conjugated systems. [8] But how great are these effects?…”

“…[6] It is perhaps the non-covalent interactions which have attracted the greatest attention in OSC molecular design, [7,8] many materials seemingly involving heteroatoms in the search of "conformational locks" and planarized conjugated systems. [8] But how great are these effects? This Perspective article highlights some of the aspects of introducing heteroatoms in organic semiconducting polymers and small molecules.…”