Presentation Information
[9p-P06-10]Depth-resolved evaluation of electronic states and composition of CH3NH3PbI3 using X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy
〇(B)Koki Sawai1, Aruto Akatsuka2, Ryota Tozaki2, Masato Iwasawa3, Hiroyuki Yoshida1,2,4 (1.Chiba Univ., 2.Chiba Univ., 3.Nissan Chemical Corp., 4.Chiba Univ. MCRC)
Keywords:
Perovskite Solar Cells,Hard X-ray photoelectron spectroscopy
To efficiently extract charge carriers generated in the perovskite layer, proper interfacial energy level alignment with the charge transport layer is essential. In CH3NH3PbI3 (MAPI), it has been reported that adjusting the precursor ratio of methylammonium iodide (MAI) to lead iodide (PbI2) can modulate the energy levels to achieve favorable alignment. However, energy level variation between the surface and the bulk remains poorly understood. In this study, we evaluated the depth-dependent valence band maximum (VBM) of MAPI films fabricated with varying MAI:PbI2 ratios (1.2:1, 1:1, 1:1.2) using ultraviolet photoelectron spectroscopy (UPS, ~1 nm probing depth), X-ray photoelectron spectroscopy (XPS, ~10 nm), and hard X-ray photoelectron spectroscopy (HAXPES, ~30 nm). The conduction band minimum (CBM) was estimated using low-energy inverse photoelectron spectroscopy (LEIPS). Results show that while the surface exhibits n-type behavior, deeper regions show p-type character, indicating a consistent internal energy level gradient regardless of precursor ratio. SEM analysis supported differences in surface and bulk composition.