Enhancing the efficiency and stability of carbon-based perovskite solar cells through treatment of the CsPbI2Br surface with neostigmine bromide

[Display omitted] •NMB effectively promoted the recrystallization of intrinsic phase segregation on the surface of CsPbI2Br film and enhanced the crystal integrity of perovskite surface.•Bromine ions (Br−) can occupy halide vacancies, reducing the defect density of the perovskite surface and improving the energy level arrangement between the perovskite and the carbon electrode.•The champion device not only exhibits excellent stability but also achieves a high power conversion efficiency (PCE) of 14.15%. Carbon-based all-inorganic perovskite solar cells (C-PSCs) are reknown for their inexpensive manufacturing process. However, the perovskite constituents in C-PSCs are susceptible to the formation of numerous structural defects and halide vacancies, which can induce substantial energy level misalignments between the light-absorbing layer and the carbon electrode. This discrepancy hinders the extraction and transfer of holes, thereby adversely affecting the overall efficiency of the device. In this study, we propose an interfacial post-treatment strategy aimed at reinforcing perovskite layers through the application of Neostigmine bromide (NMB) as a modifier. NMB effectively promoted the recrystallization of intrinsic phase segregation on the surface of CsPbI2Br film and enhanced the crystal integrity of perovskite surface. Furthermore, bromine ions (Br−) can occupy halide vacancies. Incorporating NMB at the interface significantly reduces the surface defect concentration of the perovskite layer and optimizes the energy level alignment with the carbon electrode. Experimental results demonstrate that the optimized device exhibits remarkable stability and achieves an striking power conversion efficiency (PCE) of 14.15%. This research lays the foundation for the development of cost-effective, high-performance, and durable all-inorganic perovskite solar cells.