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Rosyadi AS, Lin YX, Peng YH, Ho CH. Axially-Polarized Excitonic Series and Anisotropic van der Waals Stacked Heterojunction in a Quasi-1D Layered Transition-Metal Trichalcogenide. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2406781. [PMID: 39099435 DOI: 10.1002/advs.202406781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Revised: 07/17/2024] [Indexed: 08/06/2024]
Abstract
Anisotropic optical 2D materials are crucial for achieving multiple-quanta functions within quantum materials, which enables the fabrication of axially polarized electronic and optoelectronic devices. In this work, multiple excitonic emissions owning polarization-sensitive orientations are clearly detected in a multilayered quasi-1D ZrS3 nanoribbon with respect to the nanostripe edge. Four excitons denoted as AS1, AS2, AS, and A2 with E ⊥ b polarized direction and one prominent A1 exciton with E || b polarized emission are simultaneously detected in the polarized micro-photoluminescence (µPL) measurement of 1.9-2.2 eV at 10 K. In contrast to light emission, polarized micro-thermoreflectance (µTR) measurements are performed to identify the polarization dependence and verify the excitons in the multilayered ZrS3 nanoribbon from the perspective of light absorption. At 10 K, a prominent and broadened peak on the lower-energy side, containing an indirect resonant emission (DI) observed by µPL and an indirect defect-bound exciton peak (AInd) observed by both µPL and µTR, is simultaneously detected, confirming the existence of a quasi-direct band edge in ZrS3. A van der Waals stacked p-GaSe/n-ZrS3 heterojunction solar cell is fabricated, which demonstrates a maximum axially-polarized conversion efficiency up to 0.412% as the E || b polarized light incident onto the device.
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Affiliation(s)
- Adzilah Shahna Rosyadi
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
| | - Ying-Xuan Lin
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
| | - Yu-Hung Peng
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
| | - Ching-Hwa Ho
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials (TCECM), National Science and Technology Council, Taipei, 106, Taiwan
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Peng YH, Muhimmah LC, Ho CH. Phosphorus-Doped Multilayer In 6Se 7: The Study of Structural, Electrical, and Optical Properties for Junction Device. JACS AU 2024; 4:58-71. [PMID: 38274254 PMCID: PMC10806775 DOI: 10.1021/jacsau.3c00653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/24/2023] [Accepted: 11/27/2023] [Indexed: 01/27/2024]
Abstract
This work investigates the characteristic of layered In6Se7 with varying phosphorus (P) dopant concentrations (In6Se7:P) from P = 0, 0.5, 1, to P = 5%. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses indicate that the structure and morphology of the In6Se7:P series compounds remain unchanged, exhibiting a monoclinic structure. Room-temperature micro-Raman (μRaman) result of all the compositions of layered In6Se7:P reveals two dominant peaks at 101 ± 3 cm-1 (i.e., In-In bonding mode) and 201 ± 3 cm-1 (i.e., Se-Se bonding mode) for each P composition in In6Se7. An extra peak at approximately 171 ± 2 cm-1 is observed and it shows enhancement at the highest P composition of In6Se7:P 5%. This mode is attributed to P-Se bonding caused by P doping inside In6Se7. All the doped and undoped In6Se7:P showed n-type conductivity, and their carrier concentrations increased with the P dopant is increased. Temperature-dependent resistivity revealed a reduction in activation energy (for the donor), as the P content is increased in the In6Se7:P samples. Kelvin probe measurement shows a decrease in work function (i.e., an energy increase of Fermi level) of the n-type In6Se7 multilayers with the increase of P content. The indirect and direct band gaps for all of the multilayer In6Se7:P of different P composition are identical. They are determined to be 0.732 eV (indirect) and 0.772 eV (direct) obtained by microtransmittance and microthermoreflectance (μTR) measurements. A rectified n-n+ homojunction was formed by stacking multilayered In6Se7/In6Se7:P 5%. The built-in potential is about Vbi ∼ 0.15 V. It agrees well with the work function difference between the two layer compounds.
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Affiliation(s)
- Yu-Hung Peng
- Graduate
Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - Luthviyah Choirotul Muhimmah
- Graduate
Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - Ching-Hwa Ho
- Graduate
Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan
- Taiwan
Consortium of Emergent Crystalline Materials, National Science and Technology Council, Taipei 106, Taiwan
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Lin CC, Yang KD, Shih MC, Huang SK, Chen TP, Hsu HC, Chuang CA, Huang CY, Wang L, Chen CC, Ho CH, Chiu YP, Chen CW. Internal Built-In Electric Fields at Organic-Inorganic Interfaces of Two-Dimensional Ruddlesden-Popper Perovskite Single Crystals. ACS APPLIED MATERIALS & INTERFACES 2022; 14:19818-19825. [PMID: 35446017 DOI: 10.1021/acsami.2c00055] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
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.
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Affiliation(s)
- Cheng-Chieh Lin
- International Graduate Program of Molecular Science and Technology, National Taiwan University (NTU-MST), Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 11529, Taiwan
| | - Kai-Di Yang
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
- Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Min-Chuan Shih
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Shao-Ku Huang
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Tzu-Pei Chen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Hung-Chang Hsu
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Ching-An Chuang
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Chih-Ying Huang
- International Graduate Program of Molecular Science and Technology, National Taiwan University (NTU-MST), Taipei 10617, Taiwan
- Molecular Science and Technology Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 11529, Taiwan
| | - Lucas Wang
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Chia-Chun Chen
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Ching-Hwa Ho
- Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
- Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
| | - Ya-Ping Chiu
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Center of Atomic Initiative for New Materials (AI-MAT), National Taiwan University (NTU), Taipei 10617, Taiwan
| | - Chun-Wei Chen
- International Graduate Program of Molecular Science and Technology, National Taiwan University (NTU-MST), Taipei 10617, Taiwan
- Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
- Center of Atomic Initiative for New Materials (AI-MAT), National Taiwan University (NTU), Taipei 10617, Taiwan
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Yan H, Liang X, Dong S, Lei Y, Zhang G, Chen R, Hu J, Jing M, Wang S, Su X, Qin C, Xiao L, Jia S. Exploration of exciton dynamics in GaTe nanoflakes via temperature- and power-dependent time-resolved photoluminescence spectra. OPTICS EXPRESS 2021; 29:8880-8889. [PMID: 33820329 DOI: 10.1364/oe.418749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/27/2021] [Indexed: 06/12/2023]
Abstract
GaTe nanoflakes have been receiving much research attention recently due to their applications in optoelectronic devices, such as anisotropic non-volatile memory, solar cells, and high-sensitivity photodetectors from the ultraviolet to the visible region. Further applications, however, have been impeded due to the limited understanding of their exciton dynamics. In this work we perform temperature- and power-dependent time-resolved photoluminescence (PL) spectra to comprehensively investigate the exciton dynamics of GaTe nanoflakes. Temperature-dependent PL measurements manifest that spectral profiles of GaTe nanoflakes change dramatically from cryogenic to room temperature, where the bound exciton and donor-to-acceptor pair transition normally disappear above 100 K, while the charged exciton survives to room temperature. The lifetimes of these excitons and their evolution vs temperature have been uncovered by time-resolved PL spectra. Further measurements reveal the entirely different power-dependent exciton behaviors of GaTe nanoflakes between room and cryogenic temperatures. The underlying mechanisms have been proposed to explore the sophisticated exciton dynamics within GaTe nanoflakes. Our results offer a more thorough understanding of the exciton dynamics of GaTe nanoflakes, enabling further progress in engineering GaTe-based applications, such as photodetectors, light-emitting diodes, and nanoelectronics.
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Ho CH. Ga 2Se 3 Defect Semiconductors: The Study of Direct Band Edge and Optical Properties. ACS OMEGA 2020; 5:18527-18534. [PMID: 32743231 PMCID: PMC7392520 DOI: 10.1021/acsomega.0c02623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Direct band edge is a crucial factor for a functional chalcogenide to be applied in luminescence devices, photodetectors, and solar-energy devices. In this work, the room-temperature band-edge emission of III-VI Ga2Se3 has been first observed by micro-photoluminescence (μPL) measurement. The emission peak is at 1.85 eV, which matches well with the band-edge transition that is measured by micro-thermoreflectance (μTR) and micro-transmittance (μTransmittance) for verification of the direct band edge of Ga2Se3. The temperature-dependent μTR spectra of Ga2Se3 show a general semiconductor behavior with its temperature-energy shift following Varshni-type variation. With the well-evident direct band edge, the peak responsivities of photovoltaic response (∼6.2 mV/μW) and photocurrent (∼2.25 μA/μW at f = 30 Hz) of defect zincblende Ga2Se3 can be, respectively, detected at ∼2.22 and ∼1.92 eV from a Cu/Ga2Se3 Schottky solar cell and a Ga2Se3 photoconductor. On the basis of experimental analysis, the optical band edge and photoresponsivity properties of a III-VI Ga2Se3 defect semiconductor are thus realized.
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Affiliation(s)
- Ching-Hwa Ho
- Graduate Institute of Applied
Science and Technology, National Taiwan
University of Science and Technology, Taipei 106, Taiwan
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