High-Performance Broadband Photodetectors Based on Asymmetric All-Carbon Nano-Heterostructures

Abstract

All-carbon nano-heterostructure photodetectors based on different carbon allotropes demonstrate excellent photoelectric performance due to their ultrahigh carrier mobility, excellent optoelectronic properties, and strong interfacial coupling effects. However, the further improvement of device performance is still limited by the interfacial charge transfer and the large dark current of graphene. Herein, asymmetric all-carbon nanoheterostructures have been designed as active channels to fabricate C 60 /graphene/single-walled carbon nanotube (SWCNT) heterojunction photodetectors. With an optimal C 60 thickness of 35 nm, the asymmetric C 60 /graphene/SWCNT photodetector exhibits excellent broadband photoelectric response from the visible to NIR range (405−1064 nm) with a high responsivity of 4568 A W −1 @ 940 nm, an ultrahigh detectivity of 3.56 × 10 14 Jones @ 940 nm, and a fast response time of 2.57 ms. Importantly, the interfacial charge transfer mechanism has been for the first time investigated by combining Raman shift statistics, absorption spectra, and fluorescence lifetime with photoluminescence spectra at room temperature. Our results demonstrate that the asymmetric channel structure effectively promotes the separation and transfer efficiency of photogenerated carriers, thus enhancing the photoelectric performance of photodetectors. This work not only gives a method to characterize the interfacial charge transfer in carbon-based heterostructures but also provides a strategy to design and fabricate highperformance all-carbon nano-heterostructure photodetectors.