Fabrication of stable and efficient 2D/3D perovskite solar cells through post-treatment with TBABF4

Perovskite solar cells (PSCs), with their low cost and simple fabrication, have emerged as promising devices to solve global warming issues. In this study, tetrabutylammonium tetrafluoroborate (TBABF4) was used as a passivator to boost the performance and the stability of the fabricated PSCs. Through TBABF(4) post-treatment, the perovskite film's grain boundaries were passivated, which caused a reduction of charge traps on the surface of the perovskite layer and served as interfacial engineering at the perovskite/hole transport layer (HTL) interface. It was found that TBABF(4) can act as a source of TBA(+) cations and cause the formation of a 2D/3D heterostructure layer, which increases the stability of PSCs. Indeed, the 2D/3D structure derived from TBABF(4) solution plays the role of a shield layer to protect the surface of the perovskite layer from degradation and facilitates charge transport processes. The posttreatment of perovskite films is, thus, introduced as an approach to address both the stability and the performance of PSCs and as a step forward to commercialize PSCs.