Plasmon Coupled Colloidal Gold Nanorods for Near‐Infrared and Short‐Wave‐Infrared Broadband Photodetection

Abstract Solution‐processed plasmonic colloidal gold nanorods (Au NRs) are promising candidates leading to new photodetection applications. While plasmonic Au NRs of a specific dimension will lead to a well‐defined optical extinction due to the localized surface plasmon resonance, in photodetection applications broadband functioning is often desired. In this work, a broadband optical extinction is achieved from λ = 400 to 2000 nm by coupling colloidal Au NRs of various dimensions in a thin film form. Such an Au NR thin film is further applied on a platinum (Pt) electrode to fabricate hybrid Au‐NR/Pt photodetectors. On these hybrid Au‐NRs/Pt devices, thanks to the plasmonic‐induced photothermal effect, a clear broadband photoresponse is demonstrated covering the near‐infrared (NIR) and short‐wave‐infrared (SWIR) spectrum from λ = 800 to 2000 nm, with a <200 µs fast photoresponse time. This work suggests that suitably coupled plasmonic colloidal Au NRs and their strong photothermal effect are promising strategies for the future development of low‐cost and broadband NIR/SWIR photodetection.