Absorption and luminescence spectra of electroluminescent liquid crystals with triphenylene, pyrene and perylene units

New derivatives of triphenylene, perylene, and pyrene are described, some of which form columnar mesophases. The absorption spectra are investigated both experimentally and theoretically. The spectra calculated using the density functional tight binding (DFTB) theory are in good agreement with experimental results. The investigated compounds show photoluminescence of violet-blue (triphenylene), yellow-green (pyrene), and orange-red (perylene) colours. In addition, electroluminescence is observed in thin films of these compounds between a positively charged ITO electrode and a negatively charged aluminium electrode. The brightness of the electroluminescence decreases in the order perylene > pyrene > triphenylene. Threshold voltages below 20 V and a luminance up to 100 cd m-2 were observed.

[1]  H. Shirai,et al.  Discotic liquid crystals of transition metalcomplexes, Part 30:spontaneous uniform homeotropic alignment of octakis(dialkoxyphenoxy)phthalocyaninatocopper(II)complexes , 2001 .

[2]  B. Batlogg,et al.  An organic solid state injection laser. , 2000, Science.

[3]  J. Wendorff,et al.  Polarized electroluminescence from liquid crystalline polymers , 2000 .

[4]  H. Bock,et al.  An all-columnar bilayer light-emitting diode , 2000 .

[5]  M. Grell,et al.  Polarized electroluminescence from highly aligned liquid crystalline polymers , 2000 .

[6]  M. Grell,et al.  Polarized emission from liquid crystal polymers , 2000 .

[7]  M. Grell,et al.  Highly polarized blue electroluminescence from homogeneously aligned films of poly(9,9-dioctylfluorene) , 2000 .

[8]  Walter Riess,et al.  Temperature stability of OLEDs using amorphous compounds with spiro-bifluorene core , 1999, Optics & Photonics.

[9]  Hans-Werner Schmidt,et al.  A Combinatorial Study of the Dependence of Organic LED Characteristics on Layer Thickness , 1999 .

[10]  Peter Strohriegl,et al.  Phenylquinoxaline Polymers and Low Molar Mass Glasses as Electron-Transport Materials in Organic Light-Emitting Diodes , 1998 .

[11]  J. Wendorff,et al.  Liquid crystalline materials for light-emitting diodes , 1998 .

[12]  Jeffrey T. Roberts,et al.  Low Temperature CVD of Crystalline Titanium Dioxide Films Using Tetranitratotitanium(IV , 1998 .

[13]  W. Brütting,et al.  Electron transport in a starburst oxadiazole , 1997 .

[14]  J. Wendorff,et al.  Preliminary communication Multilayer light emitting diodes based on columnar discotics , 1997 .

[15]  Stephen R. Forrest,et al.  Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques. , 1997, Chemical reviews.

[16]  J. Brédas,et al.  Electronic structure and optical properties of electroluminescent spiro-type molecules , 1997 .

[17]  A. Greiner,et al.  Multicoloured chromophore for white‐light‐emitting diodes , 1997 .

[18]  Ching Wan Tang,et al.  Organic electroluminescent devices with improved stability , 1996 .

[19]  Rainer F. Mahrt,et al.  Efficient two layer leds on a polymer blend basis , 1995 .

[20]  M. Kakimoto,et al.  FABRICATION OF POLYMERIC LIGHT EMITTING DIODES BASED ON POLY(P-PHENYLENE VINYLENE) LB FILMS , 1994 .

[21]  P. Schuhmacher,et al.  Fast photoconduction in the highly ordered columnar phase of a discotic liquid crystal , 1994, Nature.

[22]  N. Kawasaki,et al.  Bright blue electroluminescence from hole transporting polycarbonate , 1992 .

[23]  H. Bässler,et al.  Progress towards processible materials for light‐emitting devices using poly(p‐phenylphenylenevinylene) , 1992 .

[24]  Katsutoshi Nagai,et al.  Organic electroluminescent devices based on molecularly doped polymers , 1992 .

[25]  Tetsuo Tsutsui,et al.  Double-heterostructure electroluminescent device with cyanine-dye bimolecular layer as an emitter , 1991 .

[26]  R. N. Marks,et al.  Light-emitting diodes based on conjugated polymers , 1990, Nature.

[27]  Tetsuo Tsutsui,et al.  Organic electroluminescent device having a hole conductor as an emitting layer , 1989 .

[28]  Tetsuo Tsutsui,et al.  Organic Electroluminescent Device with a Three-Layer Structure , 1988 .

[29]  C. Tang,et al.  Organic Electroluminescent Diodes , 1987 .

[30]  A. Heeger,et al.  Visible light emission from semiconducting polymer diodes , 1991 .

[31]  M. I. Bán,et al.  Spectrophotometric determination of enthalpies and entropies of photoassociation for dissolved aromatic hydrocarbons , 1964 .

[32]  C. A. Parker,et al.  Delayed fluorescence of pyrene in ethanol , 1963 .