Surface reinforcement of perovskite films with heteroatom-modulated carbon nanosheets for heat-resistant solar cells†

The stability issue induced by surface defects in perovskite films remains one of the key constraints in facilitating the commercial adoption of perovskite solar cells (PSCs). Developing reliable passivation strategies based on inexpensive multifunctional passivation materials is expected to solve the above problems. Here, gelatin-derived carbon nanosheets (G-DC) prepared by a self-doping template method are developed to strengthen the surface of perovskite films, thus enhancing the heat resistance of PSCs. This two-dimensional passivation material has an ultra-thin layered structure and contains abundant heteroatoms such as N and O, which can effectively reduce surface defects and mitigate the impact of residual lead iodide in perovskite films. The excellent interfacial compatibility of G-DC promotes more efficient carrier extraction at the rear interface of PSCs, greatly reducing non-radiative recombination. Thanks to these, the optimal device with G-DC modification achieves a power conversion efficiency of up to 21.65%, which is higher than the 20.32% of the control device. Furthermore, thermally induced organic component loss and ion migration of the modified PSCs are significantly suppressed due to the interactions between G-DC and the perovskite. Finally, the G-DC-modified devices retain 87% of the initial efficiency after aging under an inert atmosphere at 85 °C for 720 h.