Halide-Substituted Electronic Properties of Organometal Halide Perovskite Films: Direct and Inverse Photoemission Studies.
Solution-processed perovskite solar cells are attracting increasing interest due to their potential in next-generation hybrid photovoltaic devices. Despite the morphological control over the perovskite films, quantitative information on electronic structures and interface energetics is of paramount importance to the optimal photovoltaic performance. Here, direct and inverse photoemission spectroscopies are used to determine the electronic structures and chemical compositions of various methylammonium lead halide perovskite films (MAPbX3, X = Cl, Br, and I), revealing the strong influence of halide substitution on the electronic properties of perovskite films. Precise control over halide compositions in MAPbX3 films causes the manipulation of the electronic properties, with a qualitatively blue shift along the I → Br → Cl series and showing the increase in ionization potentials from 5.96 to 7.04 eV and the change of transport band gaps in the range from 1.70 to 3.09 eV. The resulting light absorption of MAPbX3 films can cover the entire visible region from 420 to 800 nm. The results presented here provide a quantitative guide for the analysis of perovskite-based solar cell performance and the selection of optimal carrier-extraction materials for photogenerated electrons and holes.
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou 215123, China.
Chi
C
Li
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou 215123, China.
Jian
J
Wei
Department of Physics, Faculty of Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Mikio
M
Sato
Department of Physics, Faculty of Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Harunobu
H
Koike
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou 215123, China.
Zhong-Zhi
ZZ
Xie
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou 215123, China.
Yan-Qing
YQ
Li
Department of Physics, Faculty of Science and Technology, Tokyo University of Science , 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Kaname
K
Kanai
Division of Photo-Molecular Science III, Department of Photo-Molecular Science, Institute for Molecular Science, National institute of Natural Sciences , 38 Nishigo-naka, Myodaiji, Okazaki 444-8585, Japan.
Satoshi
S
Kera
Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Nobuo
N
Ueno
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou 215123, China.
Jian-Xin
JX
Tang
band gap; electronic structures; inverse photoemission spectroscopy; perovskite; photoemission spectroscopy