TY - JOUR
T1 - Static Rashba Effect by Surface Reconstruction and Photon Recycling in the Dynamic Indirect Gap of APbBr3(A = Cs, CH3NH3) Single Crystals
AU - Ryu, Hongsun
AU - Park, Dae Young
AU - McCall, Kyle M.
AU - Byun, Hye Ryung
AU - Lee, Yongjun
AU - Kim, Tae Jung
AU - Jeong, Mun Seok
AU - Kim, Jeongyong
AU - Kanatzidis, Mercouri G.
AU - Jang, Joon I.
N1 - Funding Information:
This work was supported by the Basic Science Research Programs (2017R1D1A1B03035539 and 2020R1F1A1069646) through the National Research Foundation of Korea (NRF), funded by the Korean government. At Northwestern this work was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, under Grant No. SC0012541 (synthesis and structural characterization).
Publisher Copyright:
© 2020 American Chemical Society. All rights reserved.
PY - 2020/12/16
Y1 - 2020/12/16
N2 - Recently, halide perovskites have gained significant attention from the perspective of efficient spintronics owing to the Rashba effect. This effect occurs as a consequence of strong spin-orbit coupling under a noncentrosymmetric environment, which can be dynamic and/or static. However, there exist intense debates on the origin of broken inversion symmetry since the halide perovskites typically crystallize into a centrosymmetric structure. In order to clarify the issue, we examine both dynamic and static effects in the all-inorganic CsPbBr3 and organic-inorganic CH3NH3PbBr3 (MAPbBr3) perovskite single crystals by employing temperature- and polarization-dependent photoluminescence excitation spectroscopy. The perovskite single crystals manifest the dynamic effect by photon recycling in the indirect Rashba gap, causing dual peaks in the photoluminescence. However, the effect vanishes in CsPbBr3 at low temperatures (<50 K) accompanied by a striking color change of the crystal, arising presumably from lower degrees of freedom for inversion symmetry breaking associated with the thermal motion of the spherical Cs cation compared with the polar MA cation in MAPbBr3. We also show that the static Rashba effect occurs only in MAPbBr3 below 90 K, presumably due to surface reconstruction via MA-cation ordering, which likely extends across a few layers from the crystal surface to the interior. We further demonstrate that this static Rashba effect can be completely suppressed upon surface treatment with polymethyl methacrylate (PMMA) coating. We believe that our results provide a rationale for the Rashba effects in halide perovskites.
AB - Recently, halide perovskites have gained significant attention from the perspective of efficient spintronics owing to the Rashba effect. This effect occurs as a consequence of strong spin-orbit coupling under a noncentrosymmetric environment, which can be dynamic and/or static. However, there exist intense debates on the origin of broken inversion symmetry since the halide perovskites typically crystallize into a centrosymmetric structure. In order to clarify the issue, we examine both dynamic and static effects in the all-inorganic CsPbBr3 and organic-inorganic CH3NH3PbBr3 (MAPbBr3) perovskite single crystals by employing temperature- and polarization-dependent photoluminescence excitation spectroscopy. The perovskite single crystals manifest the dynamic effect by photon recycling in the indirect Rashba gap, causing dual peaks in the photoluminescence. However, the effect vanishes in CsPbBr3 at low temperatures (<50 K) accompanied by a striking color change of the crystal, arising presumably from lower degrees of freedom for inversion symmetry breaking associated with the thermal motion of the spherical Cs cation compared with the polar MA cation in MAPbBr3. We also show that the static Rashba effect occurs only in MAPbBr3 below 90 K, presumably due to surface reconstruction via MA-cation ordering, which likely extends across a few layers from the crystal surface to the interior. We further demonstrate that this static Rashba effect can be completely suppressed upon surface treatment with polymethyl methacrylate (PMMA) coating. We believe that our results provide a rationale for the Rashba effects in halide perovskites.
UR - http://www.scopus.com/inward/record.url?scp=85097886453&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85097886453&partnerID=8YFLogxK
U2 - 10.1021/jacs.0c09132
DO - 10.1021/jacs.0c09132
M3 - Article
C2 - 33217232
AN - SCOPUS:85097886453
SN - 0002-7863
VL - 142
SP - 21059
EP - 21067
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 50
ER -