title: Highly efficient graphene-based Cu(In, Ga)Se₂ solar cells with large active area.
abstract: Two-dimensional graphene has tremendous potential to be used as a transparent conducting electrode (TCE), owing to its high transparency and conductivity. To date graphene films have been applied to several kinds of solar cells except the Cu(In, Ga)Se₂ (CIGS) solar cell. In this work, we present a novel TCE structure consisting of a doped graphene film and a thin layer of poly(methyl methacrylate) (PMMA) to replace the ZnO:Al (AZO) electrode for CIGS. By optimizing the contact between graphene and intrinsic ZnO (i-ZnO), a high power conversion efficiency (PCE) of 13.5% has been achieved, which is among the highest efficiencies of graphene-based solar cells ever reported and approaching those of AZO-based solar cells. Besides, the active area of our solar cells reaches 45 mm(2), much larger than other highly efficient graphene-based solar cells (>10%) reported so far. Moreover, compared with AZO-based CIGS solar cells, the total reflectance of the graphene-based CIGS solar cells is decreased and the quantum efficiency of the graphene-based CIGS is enhanced in the near infrared region (NIR), which strongly support graphene as a competitive candidate material for the TCE in the CIGS solar cell. Furthermore, the graphene/PMMA film can protect the solar cell from moisture, making the graphene-based solar cells much more stable than the AZO-based solar cells.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China. xdxiao@phy.cuhk.edu.hk.
authors.forename: Ling
authors.initials: L
authors.lastname: Yin
authors.forename: Kang
authors.initials: K
authors.lastname: Zhang
authors.forename: Hailin
authors.initials: H
authors.lastname: Luo
authors.forename: Guanming
authors.initials: G
authors.lastname: Cheng
authors.forename: Xuhang
authors.initials: X
authors.lastname: Ma
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Xiong
authors.forename: Xudong
authors.initials: X
authors.lastname: Xiao