Optimization of perovskite/carbon interface performance using N-doped coal-based graphene quantum dots and its mechanism analysis

Optimizing the interfacial properties between perovskite and carbon electrodes has always been an important way to improve the photoelectric conversion efficiency (PCE) of carbon-based perovskite solar cells (C-PSCs) and facilitate their commercialization. In this paper, nitrogen-doped graphene quantum dots (N-GQDs) with fluorescent properties were successfully prepared using inexpensive coal as raw material by a facile and environmentally friendly chemical reagent oxidation. The results show that the electron-rich pyridinic nitrogen in N-GQDs can act as Lewis bases to form coordination bonds with uncoordinated lead ions by sharing electron pairs, thereby reducing the defect density and nonradiative recombination of photo-generated electron-hole, and extending lifetime of charge carriers. In addition, due to the passivation of N-GQDs, the hysteresis effect of the device is significantly reduced and the long-term stability is also improved. By optimizing the concentration, the PCE of C-PSCs achieved a max-imum of 14.31%, which was improved by 20.25% compared with 11.90% of the pristine C-PSCs. This work provides a facile, environmentally friendly and efficient strategy for improving the overall performance of C-PSCs using inexpensive coal-based N-GQDs.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

Optimizing the interface properties between perovskite and carbon electrodes is crucial for improving the photoelectric conversion efficiency and commercialization of carbon-based perovskite solar cells (C-PSCs). In this study, nitrogen-doped graphene quantum dots (N-GQDs) were successfully prepared from inexpensive coal using a facile and environmentally friendly chemical oxidation method. The N-GQDs with electron-rich pyridinic nitrogen effectively reduced defect density and nonradiative recombination, thereby extending the lifetime of charge carriers. The PCE of C-PSCs reached a maximum of 14.31% after optimizing the concentration, demonstrating a 20.25% improvement compared to pristine C-PSCs. This work provides a facile and efficient strategy for enhancing the overall performance of C-PSCs using inexpensive coal-based N-GQDs.