Enhancing optoelectronic performance of two-dimensional organic perovskites through anchoring groups: A first-principles study

Anchoring groups interface modification is one of the effective methods for regulating the stability and photoelectric properties of two-dimensional (2D) perovskites. In this paper, Pb-free 2D organic calcium titanium perovskite MA2SnI4 are chosen to investigate the effects of 11 representative anchoring groups on the crystal structure, electronic properties, and optical properties of 2D organic perovskites by using First-principles calculation methods. The results show that the role played by halogen bonds in the stabilization of the interfacial structure cannot be ignored. Meanwhile, the adsorption of anchoring groups affects the stability of 2D MA2SnI4 to different degrees. Interestingly, the adsorption of anchoring groups caused the absorption spectra of 2D MA2SnI4 to be red-shifted with different degrees, among which the addition of fluorobenzene red-shifted the absorption spectra by the farthest distance, whereas benzoic acid not only red-shifted the absorption spectra but also enhanced the light absorption intensity of them the most. The redshift of the absorption spectra and the increase in light absorption intensity result in improved light absorption efficiency of 2D MA2SnI4 near visible light. This provides a good reference value for the design of solar cells.