[Investigation on electroluminescence of MEH-PPV/ZnSe nanocomposite device]

ZnSe nanocrystals were synthesized in aqueous solution by using mercapto-acetate acid as stabilizer. Products were characterized by X-ray diffraction patterns (XRD) and X-ray photoelectron spectra (XPS). A surfactant was used to transfer the nanocrystals from the aqueous solution to organic solvent, so that ZnSe and MEH-PPV could be mixed sufficiently and were used as an emitting layer in a multilayered electroluminescence device: Glass/ITO/MEH-PPV : ZnSe /BCP/Alq3/LiF/Al. A comparison between absorption spectra and photoluminescence spectra of ZnSe nanocrystals and MEH-PPV thin film exhibits an effective energy transfer from ZnSe nanocrystals to MEH-PPV, which is one reason for the existing difference between photoluminescence spectrum and electroluminescence spectrum of MEH-PPV : ZnSe nanocomposite film. The recombination mechanism of the nanocomposite film under photoexcitation and electric injection was discussed respectively. The authors investigated the photo- and electroluminescence properties of the device, and found that the EL intensity of ZnSe nanocrystals increased with the applied voltages. The I-V characteristic of this device is similar to that of a classic diode.