6 research outputs found
Indanthrone dye revisited after sixty years
Indanthrone, an old, insoluble dye can be converted into a solution processable, self-assembling and electroluminescent organic semiconductor, namely tetraoctyloxydinaptho[2,3-a:20,30-h]phenazine (P-C8), in a simple one-pot process consisting of the reduction of the carbonyl group by sodium dithionite followed by the substitution with solubility inducing groups under phase transfer catalysis condition
New semiconducting naphthalene bisimides N-substituted with alkoxyphenyl groups: spectroscopic, electrochemical, structural and electrical properties
International audienc
Soluble Flavanthrone Derivatives: Synthesis, Characterization, and Application to Organic Light-Emitting Diodes
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 Pmath formula 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 %
Structural, Spectroscopic, Electrochemical, and Electroluminescent Properties of Tetraalkoxydinaphthophenazines: New Solution-Processable Nonlinear Azaacenes
A series
of solution-processable tetraalkoxy-substituted dinaphtho[2,3-<i>a</i>:2′,3′-<i>h</i>]phenazines were
synthesized by reductive functionalization of indanthrone (6,15-dihydrodinaphtho[2,3-<i>a</i>:2′,3′-<i>h</i>]phenazine-5,9,14,18-tetraone),
an old intractable dye. The melting point of these new compounds was
found to decrease from 204 °C to 98 °C upon extension of
the number of carbons from 4 to 12 in the alkoxy substituent. All
derivatives show a strong tendency to self-organize in 2D as evidenced
by STM investigations of monolayers deposited on HOPG. The 2D structure
is less dense and shows different alkoxy group interdigitation pattern
as compared to the 3D structure determined from the X-ray diffraction
data obtained for the corresponding single crystals. Electrochemical,
absorption, and emission properties of tetraalkoxy-substituted dinaphtho[2,3-<i>a</i>:2′,3′-<i>h</i>]phenazines, studied
in solution, are essentially independent of the length of the alkoxy
substituents. All derivatives exhibit high photoluminescence quantum
yield, approaching 60%. When molecularly dispersed in a solid matrix
consisting of poly(9-vinylcarbazole) (PVK) (60 wt %) and (2-<i>tert</i>-butylphenyl-5-biphenyl-1,3,4-oxadiazole) (PBD) (40
wt %) (so-called “guest/host configuration”), they show
green electroluminescence due to an effective energy transfer from
the matrix to the luminophore. The best light-emitting diodes were
obtained for the butoxy derivative showing a luminance approaching
1500 cd/m<sup>2</sup> and a luminous efficiency over 0.8 cd/A