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

All-carbon nano-heterostructure photodetectors basedon differentcarbon allotropes demonstrate excellent photoelectric performancedue to their ultrahigh carrier mobility, excellent optoelectronicproperties, and strong interfacial coupling effects. However, thefurther improvement of device performance is still limited by theinterfacial charge transfer and the large dark current of graphene.Herein, asymmetric all-carbon nano-heterostructures have been designedas active channels to fabricate C-60/graphene/single-walledcarbon nanotube (SWCNT) heterojunction photodetectors. With an optimalC(60) thickness of 35 nm, the asymmetric C-60/graphene/SWCNTphotodetector exhibits excellent broadband photoelectric responsefrom the visible to NIR range (405-1064 nm) with a high responsivityof 4568 A W-1 @ 940 nm, an ultrahigh detectivityof 3.56 x 10(14) Jones @ 940 nm, and a fast responsetime of 2.57 ms. Importantly, the interfacial charge transfer mechanismhas been for the first time investigated by combining Raman shiftstatistics, absorption spectra, and fluorescence lifetime with photoluminescencespectra at room temperature. Our results demonstrate that the asymmetricchannel structure effectively promotes the separation and transferefficiency of photogenerated carriers, thus enhancing the photoelectricperformance of photodetectors. This work not only gives a method tocharacterize the interfacial charge transfer in carbon-based heterostructuresbut also provides a strategy to design and fabricate high-performanceall-carbon nano-heterostructure photodetectors.