Abstract
In recent years, using two-dimensional (2D) materials to realize broadband photodetection has become a promising area in optoelectronic devices. Here, we successfully synthesized SnSe nanosheets (NSs) by a facile tip ultra-sonication method in water-ethanol solvent which was eco-friendly. The carrier dynamics of SnSe NSs was systematically investigated via a femtosecond transient absorption spectroscopy in the visible wavelength regime and three decay components were clarified with delay time of τ1 = 0.77 ps, τ2 = 8.3 ps, and τ3 = 316.5 ps, respectively, indicating their potential applications in ultrafast optics and optoelectronics. As a proof-of-concept, the photodetectors, which integrated SnSe NSs with monolayer graphene, show high photoresponsivities and excellent response speeds for different incident lasers. The maximum photo-responsivities for 405, 532, and 785 nm were 1.75 × 104 A/W, 4.63 × 103 A/W, and 1.52 × 103 A/W, respectively. The photoresponse times were ~22.6 ms, 11.6 ms, and 9.7 ms. This behavior was due to the broadband light response of SnSe NSs and fast transportation of photocarriers between the monolayer graphene and SnSe NSs.
Highlights
Graphene-based photodetectors have attracted significant research interest [1,2,3]
The light wavelength of sensing in this hybrid graphene photodetectors is mainly based on the absorption band of NSs or quantum dots (QDs)
SnSe NSs dispersed in water-ethanol were synthesized from SnSe bulk using four main processes of grinding, water bath and ice-bath probe sonication, and centrifugation as shown in Figure 1
Summary
Graphene-based photodetectors have attracted significant research interest [1,2,3]. the photo-responsivity is restricted by the low absorption of the one-atom thick graphene [4]. Several studies have reported that one of the effective ways is to construct hybrid structures, such as graphene-nanosheets (NSs) or graphene-quantum dots (QDs) This hybrid structure complements the low carrier mobility of nanomaterials and exhibits excellent chemical stability under incident radiation. Sun et al successively reported two kinds of photodetectors, which are based on oil phase QDs-graphene, these two devices can respond 895 nm light with a responsivity of 107 AW−1 and 405 nm light with a responsivity of 103 AW−1 , and the sense time is about 0.26 s and 0.52 s, respectively [7,8]. The light wavelength of sensing in this hybrid graphene photodetectors is mainly based on the absorption band of NSs or QDs. it turns out to be vital to explore facile and green methods to fabricate NSs or QDs and apply them with graphene to achieve broadband and sensitive detection. The fast photo-response time was ~22.6 ms, 11.6 ms, and 9.7 ms, respectively
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