Functionalized organic semiconductor molecules to enhance charge carrier injection in electroluminescent cell

Abstract

Organic semiconductor (OSC) materials as a charge carrier interface play an important role to improve the device performance of organic electroluminescent cells. In this study, 4,4"-bis(diphenyl amino)-1,1':3',1"-terphenyl-5'-carboxylic acid (TPA) and 4,4"-di-9H-carbazol-9-yl-1,1':3',1"-terphenyl-5'-carboxylic acid (CAR) has been designed and synthesized to modify indium tin oxide (ITO) layer as interface. Bare ITO and PEDOT:PSS coated on ITO was used as reference anode electrodes for comparison. Furthermore, PEDOT:PSS coated over CAR/ITO and TPA/ITO to observe stability of OSC molecules and to completely cover the ITO surface. Electrical, optical and surface characterizations were performed for each device. Almost all modified devices showed around 36% decrease at the turn on voltage with respect to bare ITO. The current density of bare ITO, ITO/CAR and ITO/TPA were measured as 288, 1525 and 1869 A/m(2), respectively. By increasing current density, luminance of modified devices showed much better performance with respect to unmodified devices. (C) 2017 Elsevier B.V. All rights reserved.