Solution-Processed Gold Nanorods Integrated with Graphene for Near-Infrared Photodetection via Hot Carrier Injection.

Graphene-based photodetectors have attracted wide interest due to their high-speed, wide-band photodetection and potential as highly energy-efficient integrated devices. However, the inherently low-absorption cross-section and nonselective spectra response hinder its utilization as a high-performance photodetector. Here, we report a solution-processed and high-spectral-selectivity photodetector based on a gold nanorods (Au NRs)-graphene heterojunction with near-infrared (NIR) detection. Au NRs are used as a subwavelength scattering source, and nanoantennas with wide light absorption range from ultraviolet to near-infrared via tuning their geometry. Photons couple into Au NRs, exciting resonant plasmas and generating hot carriers that pump into graphene, resulting in selective NIR photodetection. A flexible NIR photodetector is also demonstrated based on this simple structure. Au NRs can achieve variable resonance frequencies by the design of different aspect ratios as nanoantennae for graphene, which promises the selective amplifying of the photoresponsivity and enables highly specific detection.