Controlling Conformation By Intramolecular Nonbonding Interaction For Soft-Conjugated Optoelectronic Functional Molecules

The unique optoelectronic properties of the rigid ?-conjugated structures are widely used in various organic semiconducting devices,while the planar rigid structures usually leads to poor solubility of the material and it is difficult to produce at low cost,resulting the upsurge of the solution processing materials,and how to improve the molecular skeleton plane becoming research hotspot.In this paper,the soft-conjugated molecules are proposed by carefully adjusting the strength of the intramolecular nonbonding interactions to realize the non-planar in the solution state and planar structures in solid state to enhance the photoelectric properties for the inherent contradiction between the optoelectronic properties and the processing properties of the organic ?-conjugated molecules.It is sufficient to overcome the effects of thermal fluctuations,spatial effects and other repulsive forces to force adjacent aromatic ring being plane by using strong enough weak interactions with S···N,N···H and F···S to construct soft-conjugated molecules,and the torsional barriers,the frontier orbital energy levels,energy gaps,reorganization energies analysis found the photophysical properties comparable to those of rigid-conjugated molecules.This paper elaborates the design principle of soft-conjugated molecules in detail.Based on the theory of integrated density functional theory,the optoelectronic properties of furan and thiophene building blocks were studied.It was found that the furan system could maintain the soft-conjugated structure even if there was no weak interaction.The torsion barrier analysis found that furan could also be used for solution preparation and highly delocalized frontier molecular orbitals,suitable energy levels,energy gaps,absorption and emission spectra,and smaller Stokes shift have demonstrated that the furan building block possesses optoelectronic properties similar to thiophene.Based on the excellent optoelectronic properties of furan building blocks,the oligomers based on thiophene and furan units were studied.It was found that the oligomers still maintained the molecular skeleton to plane with the increase of the chain,and the molecular orbitals delocalized from the whole skeleton,while RDG analysis and torsion barrier analysis found that polyfuran has the processing properties and has excellent potential for high device performance.