Electrical Characteristics of a Turmeric Dye-Based Organic Thin Film Device and the Effect of Light on Barrier Height

Abstract

: Herbal (turmeric) dye-based organic thin film is fabricated and characterized to prepare thin film electronic devices (i.e., Al/turmeric/Cu diodes) for optoelectronic applications. The temperature-dependent current–voltage (I-V) characteristics were evaluated considering different conditions. The values of the ideality factor (n), series resistance (R S ) and shunt resistance (R sh ) of the Al/turmeric/Cu diode were calculated using thermionic emission theory. The rectification ratio was found to be very high, and the current increased with the temperature. At 65 ◦ C, R S was 56 K Ω , and at 28 ◦ C, R S was 1.06 M Ω . The values of n, R S and R sh were found to be 6.56, 8 K Ω and 100 K Ω , respectively. An interesting result obtained from the present work was that the series resistance decreased with the temperature, indicating the semiconducting behavior of the present dye material. with Fermi-level pinning at the interface region. In this device, the thickness of the dye layer was greater in comparison to the normal Schottky diode. The greater thickness of the curcumin layer led to a huge recombination of electrons and holes. Therefore, probable reasons for the high values of the ideality factor of the devices are a potential drop in the interfacial layer, the presence of excess current and a high recombination current through the interfacial states between the metal curcumin layers [19]. It was observed for this device that the values for R s and R sh were 8 and 100 K Ω , respectively. Using Figures 2 and 5 we have calculated the values of R s and n.