Graphene oxide derivatives as hole- and electron-extraction layers for high-performance polymer solar cells

Owing to their solution processability, unique two-dimensional structure, and functionalization-induced tunable electronic structures, graphene oxide (GO) and its derivatives have been used as a new class of efficient hole- and electron-extraction materials in polymer solar cells (PSCs). Highly efficient and stable PSCs have been fabricated with GO and its derivatives as hole- and/or electron-extraction layers. In this review, we summarize recent progress in this emerging research field. We also present some rational concepts for the design and development of the GO-based hole- or electron-extraction layers for high-performance PSCs, along with challenges and perspectives.