title: Enhanced Conversion Efficiency of III-V Triple-junction Solar Cells with Graphene Quantum Dots.
abstract: Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the InGaP top subcell.
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Tzu-Neng
authors.initials: TN
authors.lastname: Lin
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Svette Reina Merden S
authors.initials: SR
authors.lastname: Santiago
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Jie-An
authors.initials: JA
authors.lastname: Zheng
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Yu-Chiang
authors.initials: YC
authors.lastname: Chao
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Chi-Tsu
authors.initials: CT
authors.lastname: Yuan
authors.affiliation: Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Ji-Lin
authors.initials: JL
authors.lastname: Shen
authors.affiliation: Institute of Nuclear Energy Research, P. O. Box 3-11, Lung-Tan 32500, Taiwan.
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
authors.forename: Cheng-An J
authors.initials: CJ
authors.lastname: Lin
authors.affiliation: Department of Chemical Engineering, Chung Yuan Christian University, Chungli, 32023, Taiwan.
authors.forename: Wei-Ren
authors.initials: WR
authors.lastname: Liu
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan.
authors.forename: Ming-Chiang
authors.initials: MC
authors.lastname: Cheng
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan.
authors.forename: Wu-Ching
authors.initials: WC
authors.lastname: Chou