Fabrication and properties of compact (CH3NH3)3Bi2I9 perovskite solar cell by the hot immersion method

In this paper, the performance of the methylammonium bismuth iodide (MBI) solar cells device fabricated using the hot immersion method (HIM) is evaluated for the first time. The hot immersion time (HIT) varied between 1 h and 24 h to obtain a compact MBI film. The scanning electron microscopy images visually depicted that the compact MBI film was fabricated at 24 h. The cross-sectional SEM image confirmed the uniformity and smoothness of the film, while the Dektak measurement revealed that the surface roughness decreased as the HIT was increased to 24 h. The crystallinity of the MBI film showed much improvement and UV–vis showed the extended absorption of light towards the visible region. The performance of MBI solar cells indicates five times and four times increment in the voltage and the efficiency, respectively. Our findings provide a new route to design a better absorber film in the bismuth-perovskite solar cells (Bi-PeSCs) device development using a simple method in the future. © 2022 The Authors