THE DEVICE PERFORMANCE DUE TO VARIATION OF PVK CONCENTRATION ACTED AS THE HOLE TRANSPORT LAYER THROUGH BLUE ORGANIC LIGHT EMITTING DIODE BY USING EMISSIVE LAYER DPVBI.

Abstract

Bi-layer devices of the structure ITO/PVK/DPVBi/Al with the thickness of 4,4’bis(2, 2’-diphenyl vinyl)-1,1’ biphenyl (DPVBi) 56 nm were fabricated. In this study the performance of the device has been observed through variation in the Poly(9 vinylcarbazole) (PVK) concentration as the hole transport layer (HTL). The relation between PVK concentration and the threshold voltage, maximum voltage, and maximum current as well as luminance has been identified. The device performance was analyzed in the perspective of current voltage curved (I-V) and light intensity characteristic. From the result, the device with PVK concentration 0.7% showed the optimum performance at the threshold voltage 13.0 V and the maximum current achieved was 12.7 mV. The device is found to emit blue light spectrum centred at peak 371.92 nm with the maximum voltage 14 V, whereas the maximum luminous intensity with optimum luminance are 1.04×10⁶ candela and 0.212 cd/m². DPVBi acted as the emissive EL layer was embedded by thermal evaporation while PVK film was prepared by spin coated technique.