High rectification in organic diodes based on liquid crystalline phthalocyanines.
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2015
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Abstract
The optical and electrical properties of mesogenic metal-free and metalated phthalocyanines (PCs) with
a moderately sized and regioregular alkyl periphery were investigated. In solution, the individualized
molecules show fluorescence lifetimes of 4–6 ns in THF. When deposited as solid thin films the materials
exhibit significantly shorter fluorescence lifetimes with bi-exponential decay (1.4–1.8 ns; 0.2–0.4 ns) that
testify to the formation of aggregates via p–p intermolecular interactions. In diode structures, their pronounced
columnar order outbalances the unfavorable planar alignment and leads to excellent rectification
behavior. Field-dependent charge carrier mobilities are obtained from the J–V curves in the trap-limited
space-charge-limited current regime and demonstrate that the metalated PCs display an improved
electrical response with respect to the metal-free homologue. The excited-state lifetime characterization
suggest that the p–p intermolecular interactions are stronger for the metal-free PC, confirming that the
metallic centre plays an important role in the charge transport inside these materials.
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APOSTOL, P. et al. High rectification in organic diodes based on liquid crystalline phthalocyanines. Physical Chemistry Chemical Physics, v. 17, p. 32390-32397, 2015. Disponível em: <http://pubs.rsc.org/en/content/articlepdf/2015/cp/c5cp05582b?page=search>. Acesso em: 23 jan. 2017.