Significantly enhanced photoresponse of carbon nanotube films modified with cesium tungsten bronze nanoclusters in the visible to short-wave infrared range.

ABSTRACT

Carbon nanotube (CNT) films are promising materials for application in ultra-broadband photodetectors because their absorption range covers the entire spectrum from ultraviolet to the terahertz region, and their detection mechanism is the bolometric effect. Because of the different and limited photothermal conversion efficiencies of CNTs with respect to various wavelengths, the response performance of existing photodetector devices is unsatisfactory, particularly in the infrared band. In this paper, we propose for the first time the use of cesium tungsten bronze (Cs x WO3) nanomaterials, which have strong infrared absorption and excellent photothermal conversion properties, to decorate a CNT film for construction of a Cs x WO3-CNT composite film photodetector. When compared with CNT-based film photodetectors, the proposed Cs x WO3-CNT composite film photodetector shows a significantly enhanced broadband photoresponse over the range from visible light (405 nm) to the short-wave infrared (1550 nm) region, with an average increase in responsivity of 400% and an average increase in specific detectivity of 549%. In addition, the Cs x WO3-CNT photodetector shows a fast photoresponse, with a rise time of only 28 ms, which represents a 30% improvement over that of the CNT photodetector. This paper thus provides a new concept for the design of a high-performance broadband photodetector.