Organic Semiconducting Materials from Sulfur-Hetero Benzo[k]fluoranthene Derivatives: Synthesis, Photophysical Properties, and Thin Film Transistor Fabrication
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文摘
A new family of air-stable sulfur-hetero oligoarenes based on the benzo[k]fluoranthene unit has been facilely developed as the active materials for thin film organic field-effect transistors. The Diels−Alder reaction between cyclopentadienone 1 and 2,2′-(ethyne-1,2-diyl)bisthiophene followed by decarbonylation afforded fluoranthene derivative 2. After bromination and subsequent substitution through Suzuki coupling reaction, the FeCl3-oxidative cyclization produced sulfur-hetero benzo[k]fluoranthene derivatives 8−12. In dilute chloroform solution, the absorption and emission behaviors of 2 and 4−7 showed characteristic features of the fluoranthene units, while their emission λmax red-shifted with an increase of the effective conjugation length. The steady state absorption and emission spectra of these newly synthesized compounds were thoroughly investigated and discussed. Thin film organic field-effect transistors (OFETs) using 8−11 as active materials were fabricated in a “top contact” configuration. Substituents at the skeleton play an important role in the film morphologies, which lead to different mobilities, while the charge mobilities of 8−11 from OFETs were improved after thermal annealing of the thin films. A carrier mobility as high as 0.083 cm2 V−1 s−1 and current on/off ratio of 106 were achieved through vacuum-deposited film followed by the thermal annealing process from 11.