Effect of Silver Nanoparticles in the Hole Injection Layer on the Performance of Organic Light Emitting Diodes
- PDF / 92,439 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 54 Downloads / 191 Views
0936-L05-26
Effect of Silver Nanoparticles in the Hole Injection Layer on the Performance of Organic Light Emitting Diodes Jin heon Kim, Joon Ho Lee, Tae-Heon Kim, and Chang Seoul Department of Advanced Fiber Engineering, Division of Nanosystems Engineering, Inha University, 253, Yonghyun-Dong, Nam-Gu, Incheon, 402-751, Korea, Republic of ABSTRACT The configuration of the OLED device is like this : ITO/PEDOT:PSS(Ag nanoparticle) /NPB/Alq3/Al The effect of Ag nanoparticles in the hole injection layer on the performance of Organic Light Emitting Diodes(OLED) was investigated. The hole mobility in the hole injection layer seems to be increased by Ag nanoparticles. The increased current in the hole injection layer increased the emission efficiency of the OLED. Initially, we try to incorporate silver nanoparticles(diameter:30nm) directly into the hole injection layer. However the Ag nanoparticles are aggregated into big particles, ( size 1~2 µm). We can confirm this behavior by the optical microscope. Thus, PEDOT:PSS/Ag nanoparticles solutions were filtered before spin-coating and big particles were eliminated by this process. The several silver nanoparticles concentration were selected (0.05, 0.1, 0.25 wt % of the silver nanoparticles was mixed with PEDOT;PSS solutions). Theses solutions were spin-coated on the ITO layer with 3000 rpm for 60 secs. The spin coated Ag, PEDOT:PSS solutions were heat
℃
treated at 100 in 30 min. The big Ag agglomerate was not observed in the optical microscope. Then the thermal evaporation of the NPB and Alq3 layer was conducted. The current-voltage relation was measured for the device and compared with the OLED device without Ag particle. The lumninance of the devices are also measured. The Ag nanoparticle increases the deriving current and thus increases the quantum efficiency of the OLED.
INTRODUCTION Organic light-emitting diodes (OLEDs) made from organic semiconductors are attracting attention due to the potential for fabrication of full color and flexible displays at a simple process. OLEDs are thin film structures, in which organic materials are sandwiched between two electrodes. The carriers (holes injected from the anode and electrons injected from the cathode) move towards the oppositely charged electrodes and some of them can recombine radiatively to produce light.1 OLEDs are commonly fabricated on glass substrates coated with a thin film of indium tin oxide (ITO). The ITO glass is generally employed as the anode in OLEDs because of its good electrical conductivity, high transparency over the visible region, ease of patterning, and relatively high work function. However, it has been suggested that the inefficiency of hole injection from bare ITO, poor adhesion at the ITO-organic film interface, and the diffusion of material across the ITO-organic interface have led to poor device performance of OLEDs.2,3,4,5,6 As a result, great effort has been made to modify the ITO anode, such as various treatments of the ITO surface and the deposition of very thin buffer layers between the
Data Loading...
