Atomic Origins of Tunable Quantum-Confined Electronic Structures at Conducting Edge of Two-Dimensional Ruddlesden−Popper Halide Perovskites Quantum Wells
Min-Chuan Shih1, Hung Chang Hsu1*, Cheng-Chieh Lin2,3, Shao-Ku Huang3, Tzu-Pei Chen1, Yung-Han Tsai3, Chia-Chun Chen4, Ya-Ping Chiu1,5, Chun-Wei Chen3,5,6
1Department of physics, National Taiwan University, Taipei, Taiwan
2International Graduate Program of Molecular Science and Technology (NTU-MST), National Taiwan University, Taipei, Taiwan
3Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
4Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan
5Center of Atomic Initiative for New Materials, National Taiwan University, Taipei, Taiwan
6Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology, Taipei, Taiwan
* Presenter:Hung Chang Hsu,
Vertical aligned two-dimensional (2D) Ruddlesden−Popper halide perovskites (RPPs) provided a path for charge transport along slab edge to avoid insulating organic barriers, improving solar cell device performance. Here, scanning tunneling microscopy and spectroscopy (STM/S) are utilized to investigate the solvent-engineered 2D RPPs, which vertically align on conducting substrate, to demonstrate the quantum-confined electronic structure at 2D RPPs edge in atomic scale. The atomic quantum well structure at 2D RPPs edge is well presented. In situ band alignment across its organic-inorganic interfaces showed that quantum-well characteristic is preserved; hence the bandgap size due to quantum confined effect is dependent on layer thickness or n value of 2D RPPs slabs. Also, n-type semiconductor characteristics with carrier density in the order of 1021cm-3 indicated the conductive edge state of 2D RPPs quantum wells. The observation reveals the quantum-confined electronic structure and conductive characteristic at 2D RPPs layer edge in atomic scale, which provides a different perspective for future nano-optoelectronic devices.

Keywords: two-dimensional perovskites, scanning tunneling microscopy, quantum-well electronic structure, organic−inorganic interface