▎ 摘　　要

Development of energy harvesting system becomes one of the most important necessities of today. In this context, nanogenerators (NGs) have attracted considerable attentions in recent years due to their potential applications such as self-powered portable devices. This review article addresses the significant development of NGs systems based on semiconducting and insulating piezoelectric materials. Further, the need of mechanical flexibility and optical transparency on the demand of various electronic applications has been highlighted. In addition, we discussed some recent studies on graphene-based NGs which have been explored for stable performance of NGs. (c) 2013 The Japan Society of Applied Physics