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 Hsu^1*, Cheng-Chieh Lin^2,3, Shao-Ku Huang³, Tzu-Pei Chen¹, Yung-Han Tsai³, Chia-Chun Chen⁴, Ya-Ping Chiu^1,5, Chun-Wei Chen^3,5,6

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, email:Hsiuta617@gmail.com

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