Effect of Zinc Oxide (ZnO) Nanoparticles on Interfacial Barrier Height and Band Bending of Phenosafranin (PSF) Dye-Based Organic Device

Abstract

In this work, the interfacial barrier height and formation of band bending are studied in a phenosafranin (PSF) dye-based organic device and the effect of zinc oxide nanoparticles on both of these device parameters is estimated. The results show that interfacial band bending influences the barrier height at the metal–organic semiconductor contact. Indium tin oxide (ITO)-coated glass and aluminium are used as front electrode and back electrode, respectively, in the device. Analysis of the current–voltage (I–V) characteristics of the device show that the barrier height is reduced from 0.81 eV to 0.67 eV in the presence of ZnO nanoparticles. The barrier height is also calculated by using the Norde method, which shows a reduction from 0.83 eV to 0.69 eV in the presence of ZnO nanoparticles. Thus the results obtained using the two methods are consistent. The presence of ZnO nanoparticles also reduces the band bending from 0.218 eV to 0.183 eV at the metal—organic dye interface. As both parameters are reduced due to the incorporation of ZnO nanoparticles, it can be concluded that the charge injection process at the interface of the metal–organic layer is improved. The improvement of the charge injection process also results in lowering the threshold voltage of the organic device from 4 V to 3.5 V.