ARI-MA: Trap-Triggered Organic Field Effect Transistor as Low-Cost, Uncooled, Highly Sensitive Solid-State Photodetectors for Radiation Sensing

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The goal of this project is to develop a type of extremely high-gain, low-noise organic photodetector as a replacement for expensive photomultiplier tubes (PMTs) for applications in the low-cost radiation detectors systems. The proposed device will use the incident photon as a switching valve to control the source-drain output current of organic field effect transistors. These photodetectors allow dramatic changing of the hole injection from electrode into semiconductor channel by the trapped-electrons-induced charge injection at the organic semiconductor-electrode interface. Because the trapped electrons are injected by the incident photons, each absorbed photon will cause a large output current change in the devices, producing a very large apparent gain. The proposed photodetector will provide a new mechanism to achieve a high gain and low noise comparable to that of PMTs driven by relative low bias, and has substantial potential to replace PMTs due to superior characteristics including compact size, robustness, high gain, low noise, low power consumption, low cost, and excellent responsivity to the photon emission from scintillator. The success of this project will yield a new generation of solid-state photodetectors to achieve the NSF/Domestic Nuclear Detection Office (DNDO)'s capital investment cost goals of less than $100 per detector/sensor. This new, low-cost photodetector may then be integrated with future low-cost nanocomposite scintillators, enabling the detection and interdiction of nuclear/radiological devices or component materials by allowing for deployment of many compact, unobtrusive detectors in remote areas - such as smuggling routes - where persistent manned surveillance would be difficult. This will significantly improve the nation?s ability to prevent nuclear or radiological attacks. Successful execution of the proposed research will also have significant importance for science, technology, and society, particularly in industrial, medical, and other defense applications. For example, an increased sensitivity photodetector would reduce the radiation dose exposed to the patient in computerized tomography scanning. This project will also add another new category of low-cost electronic device into the emerging class of printable electronics. Further, undergraduate students will be recruited from well-known undergraduate research and outreach programs at the University of Nebraska-Lincoln, including the highly successful Undergraduate Creative Activities and Research Experiences Program (UCARE) and Research Experience for Undergraduates (REU) program in the Nebraska Center of Materials and Nanoscience.