Self-Alignment of the Methylammonium Cations in Thin-Film Organometal Perovskites.
A comparative study of the electronic structure of methylammonium (CH3NH3) in organometallic lead triiodide perovskite (CH3NH3PbI3) thin films synthesized using either one- or two-step deposition protocols is performed using angle-resolved C K-edge soft X-ray absorption spectroscopy (XAS) and model calculations. We find that our XAS measurements can be accurately related to the ground-state unoccupied orbitals using a simple crystal field model. We further find that films made by the one-step deposition protocol exhibit angle-dependent features, indicating long-range alignment of the CH3NH3 molecules, although the angle-dependency decreases as the film thickness increases. No angle-dependency was observed in the films made via the two-step deposition method.
†Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.|‡Soochow University-Western University Center for Synchrotron Radiation Research, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
John A
JA
McLeod
†Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
Zhongwei
Z
Wu
†Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.|‡Soochow University-Western University Center for Synchrotron Radiation Research, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
Pengfei
P
Shen
†Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
Baoquan
B
Sun
†Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.|‡Soochow University-Western University Center for Synchrotron Radiation Research, 199 Ren'ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China.
Lijia
L
Liu
X-ray absorption spectroscopy; crystal field theory; density functional theory; organometallic halide perovskites; self-alignment