Highly Sensitive Broadband Single‐Walled Carbon Nanotube Photodetectors Enhanced by Separated Graphene Nanosheets

Abstract

that of conventional narrow-bandgap semiconductors, which enable SWCNTs to be used in semitransparent or transparent photodetectors with thinner active materials. [7] In addition, it has been theoretically and experimentally demonstrated that multiple electron-hole pairs can be generated from one high-energy photon in S-SWCNTs, [8,9] which provides the possibility for fabricating high performance photoelectronic devices.Apart from the different device architectures, the SWCNT-based photodetectors have been extensively investigated using different nanotube types as a light absorber, such as individual SWCNT, aligned SWCNT arrays, SWCNT networks, and SWCNT films. [3,10,11] Compared with the former two types, the SWCNT film/networks favor the largescale fabrication of high-performance photodetectors with low-cost due to their simple process, high optical absorption, and good device reliability. To improve the performance of SWCNT-based photodetectors, low-dimensional carbon allotropes are widely used to form all-carbon heterojunctions with SWCNTs due to the intimate electronic coupling between the two sp 2 -hybridized carbon allotropes. [12] In addition, the devices with planar structures are adopted, in which the exciton diffusion along the SWCNTs plays a major role while the exciton diffusion perpendicular to the films is suppressed. Park et al. [13] demonstrated an SWCNT/C 60 -based phototransistor with the C 60 serving as electron traps and the SWCNTs as the hole carrier. The maximum responsivity and detectivity are 97.5 A W −1 at gate voltage of −2 V and 1.17 × 10 9 Jones at 1 kHz, respectively. Except for 0D C 60 , 2D graphene has also been demonstrated to enhance significantly the carrier separation by forming the Schottky junctions with S-SWCNTs due to exceedingly high carrier mobility and thermal conductivity. [14,15] Liu et al. [3,16] demonstrate an effective charge transfer between SWCNTs and graphene in the planar nanohybrids. Zhang et al. [17] developed the SWCNT film/graphene Schottky junctions for visible-NIR photodetector. The device exhibits a fast response time of 68 µs and good reproducibility in a wide range of 50-5400 Hz. However, it is still a big challenge to further improve the performance. First, the ultrathin S-SWCNT layer means poor optical absorption, which will be difficult to meet the different application requirements. While dark current will be increased with increasing the thickness or density of SWCNTs. On the other hand, continuous graphene sheets in the planar nanohybrids give a very large dark Single-walled carbon nanotube (SWCNT)/graphene Schottky junctions have great potential for high-performance all-carbon photodetector due to their excellent optical and electronic properties and efficient charge transfer. However, the further improvement of device performance is limited by the low absorption of ultrathin SWCNTs and large dark current of continuous graphene nanosheets. Here a proof-of-concept photodetector is reported using SWCNT/separated graphene (SGR) hybrid networks. The ...

Emerging Internet of Things driven carbon nanotubes-based devices

“…The CNT optoelectronic devices also have considerable potential in neural interfaces [243]. With three cascading configurations, SWCNT film photodetectors linearly amplify the output photovoltage [244]. The Schottky junction formed in SWCNT-separated graphene has also exhibited excellent photoresponse [245].…”

Application of organic–graphene hybrids in high performance photodetectors

“…Graphene-organic hybrid materials are composites of graphene and organic photoactive materials, such as organic dyes, organic small molecules or polymer semiconductors. [33][34][35][36][37][38][39][40][41][42][43][44][45][46] Light absorption in the spectral region of such graphene-organic hybrids is tuneable by appropriately selecting the property of photoactive materials, which makes them more fascinating in the optoelectronic field. This review aims to give an overview of the progress in graphene-organic hybrid materials and their applications in high performance photodetectors.…”

“…179 In addition to 0D C60, 2D graphene has also been demonstrated to enhance significantly the carrier separation by forming Schottky junctions with SWCNTs due to exceedingly high carrier mobility and thermal conductivity. 180,181 However, the intrinsic large dark current of graphene and the poor optical absorption of the ultrathin SWCNT layer inhibit further improvement in the detectivity and on-off ratio of the devices. Zhang et al demonstrate a carbon-based photodetector using SWCNT/separated graphene (SGR) hybrid networks, which is illustrated in Fig.…”

“…7a and b. 40 In this hybrid material, graphene nanosheets were connected by SWCNTs with the dip-coating method to form a continuous network. The discontinuous graphene nanosheets exhibit a much lower dark current than the SWCNT/graphene film, which enhances the current to a large extent.…”

“…(d) Transient photoresponse of the device to pulsed illumination (1064 nm, 35 mW cm À2 ) with a frequency of 625 Hz. Copyright Advanced Optical Materials 2018 40.…”