Study Of Gold Nanoparticle Size And Shape Effect In "Far-Field" Surface Plasmon Resonance

The metal nanoparticles can enhance the performance of the oganic light emitting diodes(OLED)drastically due to the optical characteristic and electrical characteristic,which drew academic extensive attention in recent years.Our research group put forward to utilize the"far field" surface plasmon resonance(FSPR)of metal nanoparticle strengthen the organic electroluminescent with nice reproducibility,and built a facile way to emission enhancement of red,green,blue and white.It is similar to the localized surface plasmon resonance(LSPR)effect and the scattering effect,the FSPR effect has a strong correlation to size,shape and surface ligands of the metal nanoparticles.This thesis discuss the metal nanoparticles shape and size effects in the FSPR,mainly includes the following three aspects:1.The synthesis and characterization of different size,shape and surface ligands gold nanoparticles,and the enhancing effect of OLED by nanoparticles.We synthesized different sizes of spherical gold nanoparticles(5-20 nm)and gold nanorods,doped the gold nanoparticles into the PEDOT:PSS layer and fabricated the formal OLED devices when P-PPV applied as the emitting layer.The experimental results show that the condition of ligand concentration is less than the critical value,the introduction of the metal nanoparticles bring the negative effects are negligible,the device have nice reproducibility and higher electroluminescent life compare to the control device.On this basis,we compared the enhancement effects for different shape,size of the nanoparticles in different doping concentrations.For the same nanoparticles,with the concentration of the nanoparticles incresed,the enhancement effect from strong to weak;until reach the best enhancement effect,the large size nanoparticles have a better enhancement effect than the small size,and the concentration of gold nanoparticles is smaller relatively.The enhancement effect of gold nanorods significantly better than the spherical gold nanoparticles.2.The mechanistic study of the enhance device performance by gold nanoparticles.Firstly,We proved the enhancment effect in our device structure come from FSPR effect and eliminated the influence of the LSPR effect,light scattering effect and electronic effect utilize the fluorescence lifetime,variable Angle electroluminescent spectra etc.Further,according to the theory model of the far field,we compare the LSPR effect with different size and shape gold nanoparticles,and give a reasonable explanation to the experimental phenomena in the previous chapter.According to the theory of the "far-field" effect,the reflectivity of the metal surface and the phase shift at the reflection play an important role in enhancing ratio and the two parameters are the function of metal nanoparticles shapes and sizes.The reflectivity of a variety of gold nanoparticles are simulated by the FDTD,the result confirmed the large size gold nanoparticles corresponding to a higher reflectivity which caused the FSPR effect have a better enhancement effect to the OLED device,and the calculation results by the "far field"theory formula are consistent with the experimental results.We investigated the best enhancing distance between the surface of gold nanoparticles and emitters of a variety of gold nanoparticles by changing the thickness of the device,the best enhancing distance corresponding to the phase shift and the size of nanoparticles.In general,utilizing FSPR effect of the large size gold nanoparticles have a better effect to enhance the performance of the device,deriving from the high reflectivity and the appropriate phase shift of the metal nanoparticles.The metal nanoparticles with high reflectivity and the appropriate phase shift have a significance on OLED performance enhancement.3.The optical effect and electrical effect of Fe3O4 nanoparticles to enhance the performance of OLED.The relatively uniform size Fe3O4 nanoparticles were synthesized by using the method of the grinding method and introduced the Fe3O4 nanoparticles into the OLED device to improve the performance of the device,the enhancement of the current density and luminescence brightness indicate Fe3O4 nanoparticles enhance the carrier injection and transmission by the electrical effect.The Fe3O4 nanoparticles are cheap,convenient preparation and remarkable electrical effect to enhance the device performance is very meaningful.