A New Type of Explosive Chemical Detector Based on an Organic Photovoltaic Cell

A new type of chemical sensor to detect explosive related compounds has been designed and fabricated with an organic photovoltaic cell as the active element. The detection of chemical molecules is performed by optically exciting the cell while its photovoltaic open-circuit voltage is continuously sampled. Upon exposure to compounds like nitroaromatics, the sensors exhibit a significant increase in open-circuit voltage. This indicates an efficient internal energy transfer between the explosive chemicals and the organic thin film surface. It is quite unique that the organic chemical sensors directly use the open-circuit voltage as a detection indicator, while the vast majority of conventional chemical sensors are based on the change in resistance. Since the open-circuit voltage can be measured without current and can also be directly sampled or amplified in the circuits, this new type of chemical sensor is very attractive for low-power application and sensor networks for the future Internet of Things.