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Soluble Flavanthrone Derivatives: Synthesis, Characterization, and Application to Organic Light‐Emitting Diodes
Author(s) -
Kotwica Kamil,
Bujak Piotr,
Data Przemyslaw,
Krzywiec Wojciech,
Wamil Damian,
Gunka Piotr A.,
Skorka Lukasz,
Jaroch Tomasz,
Nowakowski Robert,
Pron Adam,
Monkman Andrew
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600513
Subject(s) - substituent , oled , electroluminescence , alkyl , acridine , photoluminescence , molecule , chemistry , carbazole , photochemistry , moiety , alkoxy group , materials science , crystallography , stereochemistry , organic chemistry , optoelectronics , layer (electronics)
Simple modification of benzo[ h ]benz[5,6]acridino[2,1,9,8‐ klmna ]acridine‐8,16‐dione, an old and almost‐forgotten vat dye, by reduction of its carbonyl groups and subsequent O ‐alkylation, yields solution‐processable, electroactive, conjugated compounds of the periazaacene type, suitable for the use in organic electronics. Their electrochemically determined ionization potential and electron affinity of about 5.2 and −3.2 eV, respectively, are essentially independent of the length of the alkoxyl substituent and in good agreement with DFT calculations. The crystal structure of 8,16‐dioctyloxybenzo[ h ]benz[5,6]acridino[2,1,9,8‐ klmna ]acridine ( FC‐8 ), the most promising compound, was solved. It crystallizes in space group P 1 ‾ and forms π‐stacked columns held together in the 3D structure by dispersion forces, mainly between interdigitated alkyl chains. Molecules of FC‐8 have a strong tendency to self‐organize in monolayers deposited on a highly oriented pyrolytic graphite surface, as observed by STM. 8,16‐Dialkoxybenzo[ h ]benz[5,6]acridino[2,1,9,8‐ klmna ]acridines are highly luminescent, and all have photoluminescence quantum yields of about 80 %. They show efficient electroluminescence, and can be used as guest molecules with a 4,4′‐bis( N ‐carbazolyl)‐1,1′‐biphenyl host in guest/host‐type organic light‐emitting diodes. The best fabricated diodes showed a luminance of about 1900 cd m −12 , a luminance efficiency of about 3 cd A −1 , and external quantum efficiencies exceeding 0.9 %.