Yang Jinpeng, Sato Haruki, Orio Hibiki, Liu Xianjie, Fahlman Mats, Ueno Nobuo, Yoshida Hiroyuki, Yamada Takashi, Kera Satoshi
College of Physical Science and Technology, Yangzhou University, Jiangsu, China.
Department of Photo-Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, Japan.
J Phys Chem Lett. 2021 Apr 22;12(15):3773-3778. doi: 10.1021/acs.jpclett.1c00530. Epub 2021 Apr 12.
The conduction band dispersion in methylammonium lead iodide (CHNHPbI) was studied by both angle-resolved two-photon photoelectron spectroscopy (AR-2PPE) with low photon intensity (∼0.0125 nJ/pulse) and angle-resolved low-energy inverse photoelectron spectroscopy (AR-LEIPS). Clear energy dispersion of the conduction band along the Γ-M direction was first observed by these independent methods under different temperatures, and the dispersion was found to be consistent with band calculation under the cubic phase. The effective mass of the electrons at the Γ point was estimated to be (0.20 ± 0.05) at the temperature of 90 K. The observed conduction band energy was different between the AR-LEIPS and AR-2PPE, which was ascribed to the electronic-correlation-dependent difference of initial and final states probing processes. The present results also indicate that the surface structure in CHNHPbI provides the cubic-dominated electronic property even at lower temperatures.
通过低光子强度（约0.0125 nJ/脉冲）的角分辨双光子光电子能谱（AR-2PPE）和角分辨低能逆光电子能谱（AR-LEIPS）研究了甲基碘化铅铵（CH₃NH₃PbI₃）中的导带色散。通过这些独立方法在不同温度下首次观察到沿Γ-M方向的导带清晰的能量色散，并且发现该色散与立方相下的能带计算一致。在90 K温度下，Γ点处电子的有效质量估计为（0.20±0.05）。AR-LEIPS和AR-2PPE观察到的导带能量不同，这归因于初始和最终状态探测过程中与电子相关性相关的差异。目前的结果还表明，即使在较低温度下，CH₃NH₃PbI₃中的表面结构也具有以立方为主的电子性质。
