Facile synthesis of nitrogen-doped graphene frameworks for enhanced performance of hole transport material-free perovskite solar cells

Nitrogen-doped graphene frameworks (N-GFs) with a large specific surface area (1149 m(2) g(-1)) are successfully synthesized from fumaric acid in the presence of sodium carbonate with urea added as nitrogen precursor through a facile one-step fast pyrolysis. The N-GFs can be utilized as an excellent counter electrode in hole transport material (HTM)-free perovskite solar cells (PSCs), achieving the power conversion efficiency of 10.32%, higher than the PSCs using undoped graphene frameworks. The enhanced performance of N-GF-based PSCs is probably due to the superiority of N-GFs in enabling increased charge extraction efficiency and transportation to substantially reduce charge recombination losses. This work indicates the great potential of N-GFs to replace expensive organic HTM and noble-metal electrodes in developing low-cost and efficient HTM-free PSCs.