[8a-A501-1~10] 12.5 有機太陽電池

[8a-A501-5] The Surface Electronic Structure of Hybrid Organo Lead Bromide Perovskite Single Crystals

〇米須 尚¹、Huang Xin^1,2、Paudel Tula¹、Losovyj Yaroslav³、Zhang Xin¹、Schwier Eike⁴、Kojima Yohei⁵、Zheng Mingtian⁵、Iwasawa Hideaki⁴、Shimada Kenya⁴、Saidaminov Makhsud⁶、Shi Dong⁶、Abdelhady Ahmed⁶、Bakr Osman⁶、Tsymbal Evgeny¹、Dowben Peter¹ (1.Univ. Nebraska、2.Southeast Univ.、3.Indiana Univ.、4.広大放射光セ、5.広大院理、6.KAUST)

キーワード：Electronic band structure、Density functional theory、Angle-resolved photoemission and inverse photoemission spectroscopy

The electronic structure and band dispersion of methylammonium (MA = CH₃NH₃⁺) lead bromide, CH₃NH₃PbBr₃, has been investigated through a combination of angle-resolved photoemission spectroscopy (ARPES), Fig. 1 and 2, and inverse photoemission spectroscopy (IPES), Fig. 2, as well as theoretical modeling based on density functional theory (DFT). The experimental band structures are consistent with DFT calculations. The results demonstrate the presence of a dispersive valence band in MAPbBr₃ that peaks at the point of the surface Brillouin zone (SBZ), Fig. 1. The results also indicate that the surface termination of the MAPbBr₃ is the methylammonium bromide (MABr) layer, discussed in our presentation. We find our results support models that predict a heavier hole effective mass in the region of -0.23 to -0.26 m_e, along the (SBZ center) to point of the SBZ edge. The surface appears to be n-type as a result of an excess of lead in the surface region.