title: Giant enhancement in vertical conductivity of stacked CVD graphene sheets by self-assembled molecular layers.
abstract: Layer-by-layer-stacked chemical vapour deposition (CVD) graphene films find applications as transparent and conductive electrodes in solar cells, organic light-emitting diodes and touch panels. Common to lamellar-type systems with anisotropic electron delocalization, the plane-to-plane (vertical) conductivity in such systems is several orders lower than its in-plane conductivity. The poor electronic coupling between the planes is due to the presence of transfer process organic residues and trapped air pocket in wrinkles. Here we show the plane-to-plane tunnelling conductivity of stacked CVD graphene layers can be improved significantly by inserting 1-pyrenebutyric acid N-hydroxysuccinimide ester between the graphene layers. The six orders of magnitude increase in plane-to-plane conductivity is due to hole doping, orbital hybridization, planarization and the exclusion of polymer residues. Our results highlight the importance of interfacial modification for enhancing the performance of LBL-stacked CVD graphene films, which should be applicable to other types of stacked two-dimensional films.
authors.affiliation: 1] Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore [2] NanoCore, National University of Singapore, 117576 Singapore, Singapore.
authors.forename: Yanpeng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore, Singapore.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Linjun
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Libo
authors.initials: L
authors.lastname: Gao
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Nisachol
authors.initials: N
authors.lastname: Nerngchamnong
authors.affiliation: 1] Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore [2] NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive #05-01, 117597 Singapore, Singapore.
authors.forename: Chang Tai
authors.initials: CT
authors.lastname: Nai
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: C S Suchand
authors.initials: CS
authors.lastname: Sangeeth
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore, Singapore.
authors.forename: Yuan Ping
authors.initials: YP
authors.lastname: Feng
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Nijhuis
authors.affiliation: Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore.
authors.forename: Kian Ping
authors.initials: KP
authors.lastname: Loh