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Park J, Huh S, Choi YW, Kang D, Kim M, Kim D, Park S, Choi HJ, Kim C, Yi Y. Visualizing the Low-Energy Electronic Structure of Prototypical Hybrid Halide Perovskite through Clear Band Measurements. ACS NANO 2024; 18:7570-7579. [PMID: 38377437 DOI: 10.1021/acsnano.3c12587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Organic-inorganic hybrid perovskites (OIHPs) are a promising class of materials that rival conventional semiconductors in various optoelectronic applications. However, unraveling the precise nature of their low-energy electronic structures continues to pose a significant challenge, primarily due to the absence of clear band measurements. Here, we investigate the low-energy electronic structure of CH3NH3PbI3 (MAPI3) using angle-resolved photoelectron spectroscopy combined with ab initio density functional theory. We successfully visualize the electronic structure of MAPI3 near the bulk valence band maximum by using a laboratory photon source (He Iα, 21.2 eV) at low temperature and explore its fundamental properties. The observed valence band exhibits a highly isotropic and parabolic band characterized by small effective masses of 0.20-0.21 me, without notable spectral signatures associated with a large polaron or the Rashba effect, subjects that are intensely debated in the literature. Concurrently, our spin-resolved measurements directly disprove the giant Rashba scenario previously suggested in a similar perovskite compound by establishing an upper limit for the Rashba parameter (αR) of 0.28 eV Å. Our results unveil the unusually complex nature of the low-energy electronic structure of OIHPs, thereby advancing our fundamental understanding of this important class of materials.
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Affiliation(s)
- Jeehong Park
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Soonsang Huh
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Young Woo Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Donghee Kang
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Minsoo Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Donghan Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Soohyung Park
- Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Hyoung Joon Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Yeonjin Yi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
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Liang Y, Zhao L, Li C, Du J, Shang Q, Wei Z, Zhang Q. Strong Exciton-Exciton Scattering of Exfoliated van der Waals InSe toward Efficient Continuous-Wave Near-Infrared P-Band Emission. NANO LETTERS 2023; 23:4058-4065. [PMID: 37083440 DOI: 10.1021/acs.nanolett.3c00932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
P-band emission is a superlinear low-coherence emission through exciton-exciton (X-X) scattering into photon-like states. It occurs without the prerequisites of population inversion or macroscopical coherence, rendering lower power consumption than the widely explored superlinear low-coherence emissions including superfluorescence, amplified spontaneous emission, and random lasing, and holds great potential for speckle-free imaging and interferometric sensing. However, competition processes including exciton dissociation and annihilation undermine its operation at room temperature and/or low excitation conditions. Here we report room-temperature P-band emission from InSe microflakes with excitation density of 1010 cm-2, offering 2-orders-of-magnitude lower operation density compared to the state-of-the-art superlinear low-coherence emissions. The efficient P-band emission is attributed to a large X-X scattering strength of 0.25 μeV μm2 due to enhanced spatial confinement along with intrinsic material metrics of 3D/2D exciton complex and asymmetric electron/hole mass. These findings open an avenue toward strong low-coherence near-infrared light sources based on van der Waals semiconductors.
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Affiliation(s)
- Yin Liang
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Liyun Zhao
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Chun Li
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Jiaxing Du
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Qiuyu Shang
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Zhongming Wei
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Qing Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
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