| dc.description.abstract | Due to its unique optical (electrical) properties such as wide-range absorbance of wavelength, and high carrier mobility, graphene becomes a promising candidate for photodetector devices. The ability to tune the band gap, scalability of high-throughput production, and low cost-production methods make graphene derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), attractive for light detection applications from deep ultra-violet to far infrared.
Devices that are used for sensing applications such as photodetectors and gas sensors need to be used in ambient environment. Unfortunately, reliability and stability of graphene derivatives-based devices can be significantly affected by ambient molecule species. Moreover, to maximize the utilization of graphene-derivatives properties in photodetector devices, creating a new active material or engineering the design of device structure is needed.
Therefore, to overcome these three factors, we demonstrated some solutions that are reported for the first time. Firstly, for the aim of creating a new active material that works in ambient environment, we developed a hybrid material that consists of graphene oxide femtogel (GFOG) and polymer (poly(methyl methacrylate) PMMA), and demonstrate the effects on the reliability and operational stability of the photodetector. Secondly, we designed and fabricated a GFOG photodetector that has a combination of large GOFG-metal interface area and GOFG-metal end contact in the device’s structure for the first time to enhance the responsivity of the device.
Remarkable reliability, high operation stability, and a significant photoresponsivity have been achieved in GOFG/polymer hybrid photodetector compared to GOFG photodetectors. Moreover, compared to other graphene derivatives photodetectors, a fast response time and a high responsivity have been achieved as high as 3.5s and 0.73 A W-1 respectively at low power intensity. The change in the sensing mechanism of a polymer-GOFG hybrid photodetector from bolometric to photovoltaic effect is reported for the first time.
In terms of device structure engineering, this could open a new method in engineering the nanodevice structure of electronic devices based on the aqueous solution form of graphene-derivatives as putting this type of materials between electrodes in nanoscale is quite a challenge. In terms of material, this study opens a new avenue in the engineering of graphene derivatives-based nanosensor and photodetector active material that have high reliability and responsivity which can be operated in ambient environment. Moreover, the fabrication method and the active material of the device can be used in many nanoapplications such as gas sensing and biosensing applications. | en |
