The syntheses of a series of oligo (phenylene vinylenes) (OPVs) were described. The extended π-chains were built up by sequences of Wittig reactions. Their electronic structures were systematically studied with absorption spectra, photo-luminescent spectra. The influences of the effective conjugation length on the performance of the light emitting devices were investigated.
A stable red organic light-emitting device has been realized by doping a red dye tetra-methyljuloidine (DCJT)in electron transporting layer(ETL). The structure of the device was ITO/ CuPc/ NPB/ Alq: DCJT/ MgAg, where copper phthalocyanine(CuPc) was used as a buffer layer, N, N ’-his-(1-napthyl)-N, N’- diphenyl-1, 1’ -biphenyl-4, 4’ -diamine(NPB) as the hole transporting layer, tris(8-quinolinolato) aluminum complex(Alq) as ETL, in which DCJT was doped, indium tin oxide(ITO) and MgAg were as the anode and cathode, respectively. The red emission with peak at 620nm and CIE coordinates x = 0. 63, y = 0. 37, maximum luminance 4 687cd/m2, maximum luminous efficency 0. 83lm/W were obtained. The device showed a high stability under 12mA/cm2 current density continuous operation, the half decay time reached 2 500 hours at the initial luminance 150cd/m2 and the change of driving voltage was 0. 6mV/hour in the degradation process. If 50cd/m2 is taken as the initial luminance of red device, the half decay time is considered to be 7 500 hours. (According to European Broadcasting Union(EBU) standard, for color display the ratios for red, green, blue luminance should be 30 %, 59 % and 11 %, respectively, since 100cd/m2 is often used as initial luminance of green emission in degradation test, 50cd/m2 should be adapted as the initial luminance for red emission. )
Novel low dipole moment (μ) and large first hyperpolarizability (β) electrooptic chromophores have been designed based on the special characteristic of reversed dipole moment in the excited state of exocyclic double bond (ECDB) conjugated bridge by the optimization of the substituted method, and their electronic and second-order nonlinear optical properties have been theoretically investigated by employing the AM1/FF and ZINDO/S-CI approaches. By extending the conjugation length and optimizing the donor/acceptor strength, the oscillator strength of the excited transition that contributes to the molecular nonlinearity can be further enhanced. The designed chromophores possess a larger figure of merit (FOM) than that of 4-N,N-dimethylamino-4’-nitrostilbene (DANS), and lower (5 D) ground state dipole moment.Novel low dipole moment (μ) and large first hyperpolarizability (β) electrooptic chromophores have been designed based on the special characteristic of reversed dipole moment in the excited state
WANG Peng, LI Shaojun & YE ChengCenter for Molecular Science, Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China
