Stable p-type chemical doping of graphene with reduced contact resistance by single-layer perfluorinated polymeric sulfonic acid. - Zhang, Xiao-rui; Yao, Yao; Peng, Song-ang; Zhu, Chao-yi; Huang, Xin-nan; Yan, Yun-peng; Zhang, Da-yong; Shi, Jing-yuan; Jin, Zhi (Nanotechnology, 2021)