In recent years aromatic diamine derivatives with good photoluminescent and hole transporting properties have been widely used in organic electroluminescence devices. However

their layer represents the weakest link in the electroluminescent structure considering the thermal stability of these materials. In this paper

1

5-bis[N-(1-naphthyl)-N-phenyl] naphthalene diamine(NPN) with high purity was synthesized by liquid-phase Ullmann reaction and high quality film of NPN was formed on cleaned glass substrates by vacuum evaporation. NPN and its film were characterized by FTIR spectra

1H NMR spectra

UV absorption spectra and fluorescence spectra. Differential scanning calorimeter (DSC) showed NPN has high

T

g

(129.7℃) and T m (245.7℃). Photoluminescent properties of NPN were studied by solvent effects on UV absorption spectra and fluorescence spectra. Stokes shifts of compound NPN

solved in such solvents with different polarity as cyclohexane

chloroform and ethanol

were calculated based on Bilot-Kawski equation and they were 3496

5164 and 5402cm

-1

respectively. Distinct difference of dipole moment of NPN molecule between the ground state and excited state

which was 3.74D

showed that the charge transfer in NPN molecule occurred. In addition photoluminescent properties of NPN film were investigated by UV absorption spectra and fluorescence spectra. The results indicate that the synthetic route in NPN is efficient and safe. According to UV absorption spectra the long wave absorption peak

which has contribution to fluorescence

is attributed to charge transfer transition from nitrogen to aromatic ring. UV absorption spectra and fluorescence spectra of NPN in ethanol solvent and its film show that the absorption and emitting peak have red-shift. It is indicated the molecules of NPN in its film form "J-aggregate". NPN film can emit intense blue fluorescence with peak wavelength at 448.6nm and bandwidth of 72.6nm (Chromaticity coordinates:

x

=0.1677

y

=0.1400; Purity:0.7168) under UV excitation of 365nm. It is demonstrated that NPN is a good hole transporting material and blue electroluminescent material with good thermal stability.