Coplanar Conformational Structure of π‐Conjugated Polymers for Optoelectronic Applications

Abstract

Hierarchical structure of conjugated polymers is critical to dominating their optoelectronic properties and applications. Compared to non‐planar conformational segments, coplanar conformational segments of conjugated polymers (CPs) demonstrate favorable properties for applications as a semiconductor. Herein, we will summarize recent developments in the coplanar conformational structure of CPs for optoelectronic devices. First, this review comprehensively summarizes the unique properties of planar conformational structures. Second, we emphasize the characteristics of the coplanar conformation in terms of optoelectrical properties and other polymer physics characteristics. Five primary characterization methods for investigating the complanate backbone structures are illustrated, providing a systematical toolbox for studying this specific conformation. Third, internal and external conditions for inducing the coplanar conformational structure are presented, offering guidelines for designing this conformation. Fourth, the optoelectronic applications of this segment, such as light‐emitting diodes, solar cells, and field‐effect transistors, are briefly summarized. Finally, we provide a conclusion and outlook for the coplanar conformational segment regarding molecular design and applications.This article is protected by copyright. All rights reserved

Ultraviolet Organic Laser from Rhombus Microcrystal: Benefits of Single-Molecule Emission from Twisted Structure

“…In general, organic conjugated molecules (OCMs) are widely applied in organic light-emitting diodes (OLEDs), organic lasers, organic solar cells (OSCs), and organic field-effect transistors (OFETs) due to their easy structural modification, color tunable emission, and low-cost solution processing capacity. − The intrinsic π-electron delocalization of OCMs is the original factor for obtaining optoelectronic properties, such as excellent charge-transport behavior and robust emission property, associated with their intramolecular conformation and intermolecular arrangement . The emission color and efficiency of light-emitting OCMs (LOCMs) are mostly dominated by the intrinsic band gap and electronic structures and intermolecular arrangements in the solid states. − In fact, compared to inorganic emitters, LOCMs showed a freedom of intramolecular motion and vibration to alter emission wavelength and color purity. − Compared to the nonplanar ones, the relatively planar intramolecular conformation can induce a relatively red-shifted emission behavior in the solid states . Besides, due to the diverse noncovalent interactions, the LOCMs easily tend to densely long-range intermolecular packing and aggregation, which may cause the formation of a multimolecular excited state resulting in low emission efficiency and unstable color purity. ,,,− These are undesirable for the efficient and stable ultraviolet LOCMs and their optoelectronic devices, due to their intrinsically high energy exciton and low photostability. ,, Therefore, the isolation of organic chromophores in the solid state is an effective strategy to obtain efficient and stable ultraviolet emitters for light-emitting optoelectronic applications.…”