Internal Built-In Electric Fields at Organic-Inorganic Interfaces of Two-Dimensional Ruddlesden-Popper Perovskite Single Crystals
Journal
ACS Applied Materials and Interfaces
Journal Volume
14
Journal Issue
17
Pages
19818-19825
Date Issued
2022
Author(s)
Lin C.-C
Yang K.-D
Shih M.-C
Huang S.-K
Chen T.-P
Hsu H.-C
Chuang C.-A
Huang C.-Y
Wang L
Chen C.-C
Ho C.-H
Abstract
Two-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper perovskites (OIRPPs), which consist of naturally formed "multiple quantum well (MQW)-like" structure, have received considerable interest in optoelectronic applications, owing to their outstanding optical properties and tailorable functionalities. While the quantum-confined electrons and holes at an MQW structure are under an applied electric field, the tilt of the energy bands may cause a significant influence on their optical properties. This work demonstrates the presence of internal built-in electric fields (BIEFs) at the as-synthesized 2D OIRPP single crystals. Spontaneous Franz-Keldysh oscillations, which usually act as the fingerprint to account for the presence of BIEFs in the MQW-like structures, are observed at 2D OIRPPs by the highly sensitive differential technique of modulated thermoreflectance spectroscopy. The strength of BIEFs at 2D OIRPP single crystals reduces with increased n values due to the increased width of the quantum well. The origin of the presence of BIEFs at 2D OIRPPs is further unveiled by atomically resolved scanning tunneling microscopy on their electronic band structures at organic-inorganic interfaces. Unlike the conventional III-V MQW semiconductors with the BIEFs, which are dominated by the spatial concentration gradients at heterointerfaces, the presence of BIEFs at the 2D OIRPP single crystals is attributed to the molecular dipoles within organic spacers pointing to the organic-inorganic interfaces. The discovery of internal BIEFs at the 2D OIRPPs may provide deep insight into understanding the fundamental optical properties for the future design of large-area and low-cost perovskite optoelectronic devices. © 2022 American Chemical Society. All rights reserved.
Subjects
built-in electric fields; organic-inorganic interfaces; spontaneous Franz-Keldysh oscillations; thermoreflectance modulation spectroscopy; two-dimensional perovskite
SDGs
Other Subjects
Band structure; Electric fields; Molecular spectroscopy; Optical properties; Optoelectronic devices; organic-inorganic materials; Scanning tunneling microscopy; Semiconductor quantum wells; Structural properties; Built-in electric fields; Franz-Keldysh oscillations; Modulation spectroscopy; Organic-inorganic interface; Ruddlesden-Popper; Spontaneous franz-keldysh oscillation; Thermoreflectance; Thermoreflectance modulation spectroscopy; Two-dimensional; Two-dimensional perovskite; Perovskite
Type
journal article