| Autor: |
Xing Z; Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong Special Administrative Region of the People's Republic of China., Zang Z; School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China., Li H; School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China., Ning Z; School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China., Wong KS; Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong Special Administrative Region of the People's Republic of China., Chow PCY; Department of Mechanical Engineering, The University of Hong Kong, Pok Fu Lam 999077, Hong Kong Special Administrative Region of the People's Republic of China. |
| Abstrakt: |
Engineering of quasi-two-dimensional (quasi-2D) tin halide perovskite structures is a promising pathway to achieve high-performance lead-free perovskite solar cells, with recently developed devices demonstrating over 14% efficiency. Despite the significant efficiency improvement over the bulk three-dimensional (3D) tin perovskite solar cells, the precise relationship between structural engineering and electron-hole (exciton) properties is not fully understood. Here, we study exciton properties in high-member quasi-2D tin perovskite (which is dominated by large n phases) and bulk 3D tin perovskite using electroabsorption (EA) spectroscopy. By numerically extracting the changes in polarizability and dipole moment between the excited and ground states, we show that more ordered and delocalized excitons are formed in the high-member quasi-2D film. This result indicates that the high-member quasi-2D tin perovskite film consists of more ordered crystal orientations and reduced defect density, which is in agreement with the over 5-fold increase in exciton lifetime and much improved solar cell efficiency in devices. Our results provide insights on the structure-property relationship of high-performance quasi-2D tin perovskite optoelectronic devices. |
