[16p-Z20-1~11] 12.5 Organic solar cells

▲ [16p-Z20-7] Surface structure of quasi-2D perovskite

〇(D)Abduheber Mirzehmet¹, Tomoki Ohtsuka², Muhammad Akmal Kamarudin³, Shuzi Hayase³, Tomoki Yuyama², Peter Kruger^4,5, Hiroyuki Yoshida^4,5 (1.GSAIS Chiba Univ., 2.GSSE Chiba Univ., 3.i-PERC Univ. Electro-Communication, 4.GSE Chiba Univ., 5.MCRC Chiba Univ.)

Keywords:2D perovskite, surface structure, electron spectroscopy

In this work, we investigate the surface structure of the quasi-2D perovskites with R= C₆H₅CH₃CH₂NH₃ (PEA), A= CH₃NH₃, B= Pb, and X= I. Recently we examined surface termination of solution-processed MAPbI₃ film using ultraviolet photoelectron spectroscopy (UPS) and metastable-atom electron spectroscopy (MAES). UPS examines the valence electronic states of materials based on the photoemission excited by ultraviolet photons. In MAES, the excitation source is replaced with a metastable He atom. MAES selectively sensitive to the outermost surface atoms because the metastable atoms do not penetrate into the inner layers. Therefore, a combination of the UPS and MAES enables us to obtain information about the outermost surface.
We proved that PEA ligands cover the surface of 3D perovskite in both cases. From the dependence of the concentration of PEAI in the precursor solution, we gain more precise structural information. We found that 0.5 % of PEA is insufficient to cover the 3D surface and the increased PEA ratios of 5 %, 10 %, and 20 % fully covered the surface. 1 % PEA is the intermediate case and just sufficient to cover the 3D surface. These results indicate that the plausible structure of the quasi-2D perovskite is that 2D perovskite layers covered the surface and bottom of the 3D perovskite.