Investigation of Optical and Humidity-Sensing Properties of Vanadyl Phthalocyanine-Derivative Thin Films

Abstract

In this study an active layer of Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO) has been employed in surface type humidity sensor. On top of preliminary deposited asymmetric metal electrodes, a VOPcPhO thin film was spun cast to obtain a surface type Al/VOPcPhO/Au sensor. The gap between the electrodes was 40 um. A solution of 30 mg/ml was deposited at 3000 rpm. The thickness of the VOPcPhO film was 150 nm. The capacitive effect of the sample was evaluated in the relative humidity range 0–87%RH, at room temperature. It was observed that the capacitance of the sensor increases 10 times under the effect of entire humidity range in the relative humidity level. The optical properties of VOPcPhO thin film were also investigated. The humidity-dependent capacitive properties make the sensor suitable for the application in the instruments used for environmental monitoring of humidity.

Keywords:

• Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine
• humidity sensor
• UV/Vis spectroscopy

Acknowledgement

The extended support of Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is greatly acknowledged. The authors acknowledge the enabling role of Higher Education Commission, Pakistan and appreciate the financial support through Indigenous Fellowship program. The authors are also grateful to Department of Physics, University of Malaya, Malaysia for assistance in characterizing thin film of VOPcPhO.