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Unusual Side‐Chain Effects on Charge‐Carrier Lifetime in Discotic Liquid Crystals
Author(s) -
Motoyanagi Jin,
Yamamoto Yohei,
Saeki Akinori,
Alam Md. Akhtarul,
Kimoto Atsushi,
Kosaka Atsuko,
Fukushima Takanori,
Seki Shu,
Tagawa Seiichi,
Aida Takuzo
Publication year - 2009
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200800481
Subject(s) - mesophase , discotic liquid crystal , side chain , materials science , photocurrent , liquid crystalline , ether , liquid crystal , flash (photography) , flash photolysis , charge carrier , hexagonal crystal system , crystallography , photochemistry , chemistry , optoelectronics , optics , organic chemistry , polymer , kinetics , physics , quantum mechanics , reaction rate constant , composite material
Long live the carrier! Hexa‐ peri ‐hexabenzocoronene derivatives, carrying paraffinic side chains terminated with ester–ether groups, form hexagonal columnar assemblies over a wide temperature range including room temperature. Within this temperature range, the lifetimes of charge carriers generated by laser flash photolysis are observed to be extremely long (14–40 ms).When hexa‐ peri ‐hexabenzocoronene (HBC) carries paraffinic side chains with ester–ether termini ( 1 a – 1 c ), a hexagonal columnar liquid‐crystalline (LC) mesophase forms, which is characterized by a very wide temperature range (ca. 0–300 °C). The LC materials from these HBC derivatives show characteristic electronic properties with an extremely long photocarrier lifetime. For example, by means of a flash‐photolysis time‐resolved microwave conductivity technique, the photocarrier lifetime, observed for liquid‐crystalline 1 a , is as long as 14 ms, which is four‐orders of magnitude longer than that of fully paraffinic HBC 4 (0.0011 ms). The maximum transient photoconductivities of liquid‐crystalline 1 a – 1 c are comparable to one another and also to those of HBCs without ester–ether terminals. Liquid‐crystalline 1 a exhibits an obvious photocurrent generation in response to light illumination.