Study on the Effect of Zinc Oxide Nanoparticles on Injection Barrier Height of Crystal Violet Dye Based Organic Device

Abstract

Organic devices have achieved substantial progress due to its flexibility, cost effectiveness, simple processing and wide customizability. But there are certain limitations of these devices. One of the main limitations is the lower charge injection from metal electrodes to the organic layer which affects the performance of these devices. The charge injection process is strongly dependent on the injection barrier height at metal- organic layer interface. Due to high barrier height at metal – organic layer interface, the charge injection is reduced at the interface. Attempts need to be made to reduce the injection barrier height at metal – organic layer interface to improve the charge injection process. In the present work, we have studied the injection barrier height of Indium tin oxide coated glass/Crystal violet dye/Aluminium based organic device and subsequently we have also observed the effect of zinc oxide nanoparticles on injection barrier height of this device. Indium tin oxide coated glass and aluminium are used as front electrode and back electrode respectively to form this device. The device has been prepared with and without zinc oxide nanoparticles by using spin coating technique. We have analyzed the steady state current-voltage characteristics of the device to determine the barrier height of the device. Barrier height is reduced from 0.87 eV to 0.78 eV in the presence of zinc oxide nanoparticles. The barrier height is also estimated by using another alternative method which is known as Norde method. By using Norde method, barrier height is measured which reduces from 0.83 eV to 0.77 eV in presence of zinc oxide nanoparticles. Both the methods show good consistency with each other. Reduction of the injection barrier height in presence of zinc oxide nanoparticles indicates better charge injection through the metal - organic dye interface. The higher electron mobility of zinc oxide nanoparticles facilitates efficient charge injection at the interface. Thus, this work will be informative to study the effect of zinc oxide nanoparticles on injection barrier height as it reduces the barrier height to improve the charge flow at metal – organic dye interface.