Hong You

High-Efficiency White Polymer Light-Emitting Diodes Based on Blended RGB Polymers

We have fabricated white polymer light-emitting devices (WPLEDs) from RGB polymer blending systems using ITO/PEDOT:PSS/blended polymers/LiF/Al structure. The highest current efficiency reached 5.34 cd/A and the maximum brightness value of 27,000 cd/m2 at 11.4 V was obtained. As the green dopant concentration increased, the spectrum deviated from the white because of more energy transfer from host to guest. As a result, the 450 nm blue peak was reduced by increasing green dopant ratio. On the other hand, 600 nm red shoulder peaks were slightly increased at the same conditions. Therefore, red-orange and green electroluminescence emissions are promoted by excitation energy and charge transfer from the blue host polymer to the dopants.

Improvement of Current Injection and Efficiency of Polymer Light-Emitting Diodes with the Octadecyltrichlorosilane-Treated PEDOT:PSS

We studied the improvement of a polymer light-emitting diode (PLED) by inserting an interlayer between a poly(3,4-ethylenedioxythiophene)-poly-(styrenesulfonate) (PEDOT:PSS) and an emissive layer. An octadecyltrichlorosilane (OTS) was treated on the PEDOT:PSS as the interlayer. It improved the device efficiency of the PLED from 4.4 to 5.3 cd/A, and increased the maximum luminance from 10,000 to 17,000 cd/m 2 . It increased the forward current by 20% and reduced the reverse current by 80%. Inserting the OTS layer between PEDOT:PSS and the emissive polymer reduced the injection barrier between the PEDOT:PSS and emissive layer. Therefore, the increases of the effective work function of the anode led to better hole injection and thus, higher current density.

P-146: Fluorene-Based Deep Blue Polymer Light-Emitting Diodes

We developed the new polymers, SKB1 and SKB2, exhibiting deep-blue emission (CIE: x=0.145–0.148, y=0.093–0.135). The device using SKB1 demonstrated the current efficiency of 3.11 cd/A at 6.6V with 3,251 cd/m2, and then the CIE coordinate of the emission was x=0.147 and y=0.123. The SKB2 device showed the current efficiency of 3.70 cd/A at 6.6V with 2,930 cd/m2, and then the CIE coordinate of the emission was x=0.148 and y=0.135.