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Download fileHigh-Performance Phototransistors Based on PDIF-CN2 Solution-Processed Single Fiber and Multifiber Assembly
journal contribution
posted on 29.03.2016, 00:00 by Wassima Rekab, Marc-Antoine Stoeckel, Mirella El Gemayel, Marco Gobbi, Emanuele Orgiu, Paolo SamorìHere
we describe the fabrication of organic phototransistors based on either
single or multifibers integrated in three-terminal devices. These
self-assembled fibers have been produced by solvent-induced precipitation
of an air stable and solution-processable perylene di-imide derivative,
i.e., PDIF-CN2. The optoelectronic properties of these
devices were compared to devices incorporating more disordered spin-coated
PDIF-CN2 thin-films. The single-fiber devices revealed
significantly higher field-effect mobilities, compared to multifiber
and thin-films, exceeding 2 cm2 V–1 s–1. Such an efficient charge transport is the result
of strong intermolecular coupling between closely packed PDIF-CN2 molecules and of a low density of structural defects. The
improved crystallinity allows efficient collection of photogenerated
Frenkel excitons, which results in the highest reported responsivity
(R) for single-fiber PDI-based phototransistors,
and photosensitivity (P) exceeding 2 × 103 AW–1, and 5 × 103, respectively.
These findings provide unambiguous evidence for the key role played
by the high degree of order at the supramolecular level to leverage
the material’s properties toward the fabrication of light-sensitive
organic field-effect transistors combining a good operational stability,
high responsivity and photosensitivity. Our results show also that
the air-stability performances are superior in devices where highly
crystalline supramolecularly engineered architectures serve as the
active layer.