Spatially Resolved Local Electronic Properties of 2D Lead Halide Perovskite Single Crystals Studied by X‐Ray Photoemission Electron Microscopy. Issue 1 (16th November 2022)

• Record Type: Journal Article
• Authors: Liang, Mingli; Lin, Weihua; Zhao, Qian; Li, Jun; Zhu, Lin; Sarpi, Brice; Zakharov, Alexei; Scheblykin, Ivan G.; Pullerits, Tönu; Niu, Yuran; Canton, Sophie E.; Zheng, Kaibo
• Is Part Of: Solar RRL. Volume 7:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-16
• Subjects: edge states -- lattice mismatches -- local electronic properties -- X-ray photoemission electron microscopy -- 2D lead halide perovskites; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202200795
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Recently, research on the edge states of 2D lead halide perovskites (LHPs) has been attracting much attention. The lower‐energy edge state (LES) is believed to provide an efficient pathway for the dissociation of photoexcited excitons. However, the mechanism of the LES formation remains controversial, and studies that establish precisely the local electronic properties are lacking. Herein, the first study of spatially resolved electronic structures in 2D LHP single‐crystal flakes by X‐ray photoemission electron microscopy is presented, specifically identifying the contribution from the edge area. The results show that blueshifts occur in the Pb 5 d core‐level peaks at the edge area compared to the interior area with much less difference in I 4 d core‐level peaks. The shift becomes more pronounced as n varies from 1 to 3 (≈0.2–1.0 eV). This phenomenon is attributed to the surface restructuring of the edge area induced by the release of mechanical strain through lattice expansion. This work provides an important reference on the origin of the LES of 2D LHPs and is beneficial for future optoelectronic device applications. Abstract : In 2D lead halide perovskites, a blueshift of Pb 5 d core levels at the edge area by X‐ray photoemission electron microscopy is observed. With the increase of the number of quantum wells, the blueshift becomes more obvious. Such an edge state is attributed to lattice expansion at the edge area.