Impact of Furan Substitution on the Optoelectronic Properties of Biphenylyl/Thiophene Derivatives for Light-Emitting Transistors

Abstract

Biphenylyl/thiophene systems are known for their ambipolar behavior and good optical emissivity. However, often these systems alone are not enough to fabricate the commercial-grade light-emitting devices. In particular, our recent experimental and theoretical analyses on the three-ring-constituting thiophenes end capped with biphenylyl have shown good electrical properties but lack of good optical properties. From a materials science perspective, one way to improve the properties is to modify their structure and integrate it with additional moieties. In recent years, furan moieties have proven to be a potential substitution for thiophene to improve the organic semiconductive materials properties. In the present work, we systematically substituted different proportions of furan rings in the biphenylyl/thiophene core and studied their optoelectronic properties, aiming toward organic light-emitting transistor applications. We have found that the molecular planarity plays a vital role on the optoelectronic properties of the system. The lower electronegativity of the O atom offers better optical properties in the furan-substituted systems. Further, the furan substitution significantly affects the molecular planarity, which in turn affects the system mobility. As a result, we observed drastic changes in the optoelectronic properties of two furan-substituted systems. Interestingly, addition of furan has reduced the electron mobility by one fold compared to the pristine thiophene-based derivative. Such a variation is interpreted to be due to the low average electronic coupling in furan systems. Overall, systems with all furan and one ring of furan in the center end capped with thiophene have shown better optoelectronic properties. This molecular architecture favors more planarity in the system with good electrical properties and transition dipole moments, which would both play a vital role in the construction of an organic light-emitting transistor.

A Modular and Catalytic Methodology To Access 2,5-Furan-Based Phenylene/Thiophene Oligomers through a One-Pot Decarboxylative Cross-Coupling from 5-Bromofurfural

“…Highly planar π-conjugated furan-based materials have gained popularity as promising candidates for organic optoelectronic devices. Furans alone come with some synthetic limitations due to their low stability in acidic media, their sensitivity to light, and their high reactivity with singlet oxygen; − and as such, materials containing furan heterocycles have been understudied as compared to their ubiquitous sulfur congener, thiophenes. , Nevertheless, within the past two decades, various conjugated furan compounds, oligomers, and polymers have been investigated as potential organic photovoltaics, , dye-sensitized solar cells, , organic light-emitting diodes, , organic field effect transistors (OFETs), and organic light-emitting transistors, − as well as other diverse organic optoelectronic materials. − This indicates that issues of stability can be overcome with a strategic synthetic design.…”