Insight into the photoelectrical properties of metal adsorption on a two-dimensional organic–inorganic hybrid perovskite surface: theoretical and experimental research

In order to study the photoelectric properties of the adsorption of different metal atoms on a two-dimensional (2D) perovskite surface, in this article, we built many models of Ag, Au, and Bi atoms adsorbed on 2D perovskite. We studied the rules influencing 2D perovskite adsorbing metal atoms with different n values (the n value is the number of inorganic layers of 2D perovskite; here n = 1, 2, and 3). Based on n = 2 2D perovskite, we successively used Ag, Au, and Bi metal atoms to adsorb on the 2D perovskite surface. Firstly, we calculated their adsorption energies. Based on the lowest energy principle, we found that Bi atom adsorption on the 2D perovskite surface gave the most stable structure among the three metal adsorptions because the energy of the Bi adsorption system was the smallest. Secondly, the electron transport process takes place from the s to the p orbital when Au and Ag atoms adsorb on the 2D perovskite surface, but in the Bi atom adsorption, the electron transport process takes place from the p to the p orbital, because the p–p orbital transport energy is lower than that of the s–p orbital. Therefore, Bi atom adsorption on the 2D perovskite surface can improve charge carrier transfer. Thirdly, we calculated the bond angles and bond energies of different metal adsorptions on 2D perovskite. Bi adsorption has greater interaction with the surface atoms of 2D perovskite than Ag or Au atom adsorption, which effectively enhances the surface polarization effects, and enhances the photoelectric properties of 2D perovskite. The light absorption spectrum further confirms that Bi atom adsorption has a greater impact on the 2D perovskite than the action of Ag or Au adsorption. Finally, in an experiment, we fabricated a 2D perovskite solar cell with an ITO/PEDOT:PSS/2D perovskite/PEI/Ag (Au, Bi) structure. The Bi electrode solar cell achieves the highest photoelectric conversion efficiency (PCE) of 15.16% among the three cells with forward scanning, which is consistent with the theoretical analysis. We believe that the adsorption of metals like Bi on a 2D perovskite surface as an electrode is conducive to improving the charge transport performance.