Carbon nanotube cathode with capping carbon nanosheet

•A few layers of carbon nanosheet (FLCN)-capped vertically-aligned carbon nanotubes (VACNT) film was synthesized in situ.•The square resistance of the VACNT film is significantly reduced from 1500Ω/□ to 300Ω/□ when it is capped with carbon nanosheet, because FLCN increased horizontal conductive connection.•The FLCN serves as a good electric conductivity medium material to improve the contact between VACNTs and the electrode, because FLCN increased vertical conductive connection also. Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500Ω/□ to 300Ω/□ when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.