Interface and bulk engineering by dual sulfonates toward high efficiency perovskite solar cells with better reproducibility and stability

In the study of high efficiency perovskite solar cells (PSCs), the improvement of device efficiency and stability is still limited by interface and bulk defects. In this work, a new regulation strategy is proposed, that organic sulfonate additives are introduced into the interface and perovskite film of PSCs respectively to obtain higher performance. Firstly, potassium methanesulfonate (KMsO) has acted as a multifunctional additive to passivate the surface defects of SnO2 and improve the morphology and reduce the defect density of the bottom surface of perovskite (PVSK) films. Furthermore, sodium pyridine-3-sulphonate (SP3S) has been added to the precursor of perovskite that can effectively passivate the bulk defects and improve crystallinity. This has been realized by the interactions among the sulfonate groups and pyridine groups with perovskite. Finally, the device optimized by KMsO and SP3S exhibits higher repeatability and average efficiency. The champion device has shown power conversion efficiency (PCE) of 23.8 %. What’s more, the unencapsulated device has still remained 90.8 % of the initial efficiency after storage of 1000 h at 25 °C and ∼30 %RH, while the control device has remained only 62.4 % under the same condition. These results have in general revealed a facile passivation strategy for the perovskite solar cells with composite mechanism with quite good tunability and controllability for future applications. •Dual additive engineering improves PSCs performance.•Sulfonate additives improve the bottom surface topography and enhance carrier transport.•Hydrogen and coordination bonds enhance perovskite crystallization.•A champion device efficiency of 23.8 % is achieved.