Stable All‐Organic Radicals with Ambipolar Charge Transport

Abstract

A series of neutral long-lived purely organic radicals based on the stable [4-(N-carbazolyl)-2,6-dichlorophenyl]bis(2,4,6-trichlorophenyl)methyl radical adduct (Cbz-TTM) is reported herein. All compounds exhibit ambipolar charge-transport properties under ambient conditions owing to their radical character. High electron and hole mobilities up to 10 and 10 cm V s , respectively, were achieved. Xerographic single-layered photoreceptors were fabricated from the radicals studied herein, exhibiting good xerographic photosensitivity across the visible spectrum.

Air-Stable Thin Films with High and Anisotropic Electrical Conductivities Composed of a Carbon-Centered Neutral π-Radical

“…A large number of stable neutral radicals have been reported, however, those stable even in the vaporized state under high temperature and vacuum (0.2–6 mPa) conditions to give a vapor-deposited thin film are limited. 9−12,15,17−22 In the TOT thin films, 1D π-stacking columns were formed by the strong SOMO–SOMO interaction. The anisotropic orientation of the 1D columns depended on the substrates: edge-on-oriented thin films were obtained on glass, SiO 2 , and ITO under a high deposition rate, and face-on oriented thin films were achieved on the graphite 0001 surface.…”

“…There have recently been intense challenges on the application of organic neutral radicals in various fields such as spin memories, , electrical conductors, , and thermal sensors because a molecule having an unpaired electron works under a unique operating principle based on electronic spin. − There are several successful reports on thin-film fabrications, one of the most essential and general methods for the application to electronic devices, based on open-shell molecules such as nitroxide radicals, − cyclopentadienyl radical, donor–acceptor type triphenylmethyl radicals, metal radical complexes, Blatter-type radicals, , singlet biradicaloids, , dithiadiazolyl radicals, and bis­(dithiadiazolyl) diradicals. , Neutral π-radicals, where the unpaired electron is included in a π-conjugated system, are a good candidate for thin-film fabrication because the delocalization of electronic spin increases thermodynamic stability . For example, vapor-deposited thin films of bis­(dithiadiazolyl) diradical showed photoconductivity, and vapor-deposited thin films of phenalenyl-based singlet-biradicaloid exhibited ambipolar field-effect transistor (FET) properties .…”

Stable Luminescent Radicals and Radical-Based LEDs with Doublet Emission

“…After that, many functional groups such as thiophene and phenylene were introduced to TTM to improve the electron or hole transport abilities. [46][47][48] These excellent works lay a foundation for the doublet-emission OLEDs.…”

A Simple Approach to Achieve Organic Radicals with Unusual Solid-State Emission and Extraordinary Stability

“…Besides the unique reactivity and electronic properties, organic radical species also exhibit interesting luminescence property 25,26 since its emission originated from a spin doublet, rather than a singlet or triplet exciton like conventional luminophores. Therefore, organic luminescent radicals are not only of fundamental research interest 27 but can also be exploited in applications of fluorescence probes 28 or optoelectronic devices 29 . In particular, the doublet emission of the radical emitter is still spin-allowed in OLEDs, which can circumvent the efficiency limitations imposed by triplet excitons to afford a theoretical 100% internal quantum yield [30][31][32] .…”