Efficiency and stability enhancement of perovskite solar cells using reduced graphene oxide derived from earth-abundant natural graphite

Graphene - two-dimensional (2D) sheets of carbon atoms linked in a honeycomb pattern - has unique properties that exhibit great promise for various applications including solar cells. Herein we prepared two-dimensional (2D) reduced graphene oxide (rGO) nanosheets from naturally abundant graphite flakes (obtained from Tuv aimag in Mongolia) using solution processed chemical oxidation and thermal reduction methods. As a proof of concept, we used our rGO as a hole transporting material (HTM) in perovskite solar cells (PSCs). Promisingly, the use of rGO in the hole transporting layer (HTL) not only enhanced the photovoltaic efficiency of PSCs, but also improved the device stability. In particular, the best performing PSC employing rGO nanosheets exhibited a power conversion efficiency (PCE) of up to 18.13%, while the control device without rGO delivered a maximum efficiency of 17.26%. The present work demonstrates the possibilities for solving PSC issues (stability) using nanomaterials derived from naturally abundant graphite sources.