High-Detectivity Flexible Near-Infrared Photodetector Based on Chalcogenide Ag2Se Nanoparticles

Novel, low-voltage, high-detectivity, solution-processed, flexible near-infrared (NIR) photodetectors for optoelectronic applications are realized and their optoelectronic properties are investigated for the first time. This is achieved by synthesizing Ag2Se nanoparticles (NPs) in aqueous solutions, and depositing highly crystalline Ag2Se thin films at 150 degrees C with redistributed Ag2Se NPs in aqueous inks. The high conductivity and low trap concentration of the 150 degrees C annealed Ag2Se films result from the Ag formed inside the films and the improved film quality, respectively. These factors are both critical for the realization of high-performance flexible photodetectors. The fabricated device exhibits a high detectivity of 7.14 x 10(9) Jones (above 1 x 10(9)) at room temperature, delivering low power consumption. This detectivity is superior to those of reported low band-gap semiconductor systems, although the device has undergone 0.38% compressive and tensile strains. Moreover, the performance of the device is better than that of MoS2-based phototransistors, black arsenic phosphorus field-effect transistors, or commercial thermistor bolometers at room temperature (D* approximate to 10(8) Jones), and is exposed to mid-infrared light.