Effects of Temperature and Humidity on Electrical Properties of Organic Semiconductor Orange Dye Films Deposited from Solution

In this study the effects of temperature and humidity on electrical properties of organic semiconductor orange dye (OD) have been examined. Thin films of OD were deposited from 10 wt.% aqueous solution on Au and SnO2 substrates at room temperature under normal gravity conditions, i.e., 1 g and also by using a spin coater at an angular speed of 1000 RPM. Two different types of structures: surface OD/Au and sandwich Al/OD/SnO2, Al/OD/Au were fabricated and their DC and low frequency AC characteristics were evaluated for the temperature range 30–70°C at ambient humidity of 50–80%. It was observed that the Schottky characteristics exhibited by these devices are temperature and humidity dependent. It was further observed that devices with Al electrodes act as a primary battery and the zero biased current ($I_{\text{zo}}$) increases by increasing the device temperature which is explained on the basis of temperature assisted electrochemical reaction due to the correction of Al electrode. It was found that certain sandwich structures are more sensitive to humidity than others and the observed resistance to humidity ratio for OD/Au was 5.4 whereas for Ga/OD/Au samples it was 5.0.