title: N-Doped graphene nanoplatelets as superior metal-free counter electrodes for organic dye-sensitized solar cells.
abstract: Highly efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) were developed using thin films of scalable and high-quality, nitrogen-doped graphene nanoplatelets (NGnP), which was synthesized by a simple two-step reaction sequence. The resultant NGnP was deposited on fluorine-doped SnO2 (FTO)/glass substrates by using electrospray (e-spray) coating, and their electrocatalytic activities were systematically evaluated for Co(bpy)3(3+/2+) redox couple in DSSCs with an organic sensitizer. The e-sprayed NGnP thin films exhibited outstanding performances as CEs for DSSCs. The optimized NGnP electrode showed better electrochemical stability under prolonged cycling potential, and its Rct at the interface of the CE/electrolyte decreased down to 1.73 Ω cm(2), a value much lower than that of the Pt electrode (3.15 Ω cm(2)). The DSSC with the optimized NGnP-CE had a higher fill factor (FF, 74.2%) and a cell efficiency (9.05%), whereas those of the DSSC using Pt-CE were only 70.6% and 8.43%, respectively. To the best of our knowledge, the extraordinarily better current-voltage characteristics of the DSSC-NGnP outperforming the DSSC-Pt for the Co(bpy)3(3+/2+) redox couple (in paticular, FF and short circuit current, Jsc) is highlighted for the first time.
authors: Global GET-Future Laboratory and Department of Advanced Materials Chemistry, Korea University, 2511 Sejong-ro, Sejong 339-700, Korea.
authors: Myung Jong
authors: MJ
authors: Ju
authors: Jae Cheon
authors: JC
authors: Kim
authors: Hyun-Jung
authors: HJ
authors: Choi
authors: In Taek
authors: IT
authors: Choi
authors: Sang Gyun
authors: SG
authors: Kim
authors: Kimin
authors: K
authors: Lim
authors: Jaejung
authors: J
authors: Ko
authors: Jae-Joon
authors: JJ
authors: Lee
authors: In-Yup
authors: IY
authors: Jeon
authors: Jong-Beom
authors: JB
authors: Baek
authors: Hwan Kyu
authors: HK
authors: Kim