Lithium-ion-based solid electrolyte tuning of the carrier density in   graphene
  We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate.It can induce a change in the carrier density as large as 1*10^14/cm^2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Gate modulation of the carrier density is still visible at 150 K, which is lower than the glass transition temperature of most liquid gating electrolytes. 
Jialin Zhao, Meng Wang, Hui Li, Xuefu Zhang, Lixing You, Shan Qiao, Bo   Gao, Xiaoming Xie, Mianheng Jiang
cond-mat.mtrl-sci