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Lee EJ, Lee W, Yun TH, You HR, Kim HJ, Yu HN, Kim SK, Kim Y, Ahn H, Lim J, Yim C, Choi J. Suppression of Thermally Induced Surface Traps in Colloidal Quantum Dot Solids via Ultrafast Pulsed Light. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2400380. [PMID: 38564784 DOI: 10.1002/smll.202400380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/11/2024] [Indexed: 04/04/2024]
Abstract
Thermal annealing (TA) of colloidal quantum dot (CQD) films is considered an important process for recent high-performing CQD solar cells (SCs) due to its beneficial effects on CQD solids, including enhanced electrical conductivity, denser packing of CQD films, and the removal of organic residues and solvents. However, the conventional TA for CQDs, which requires several minutes, leads to hydroxylation and oxidation on the CQD surface, resulting in the formation of trap states and a subsequent decline in SC performance. To address these challenges, this study introduces a flashlight annealing (FLA) technique that significantly reduces the annealing time to the millisecond scale. Through the FLA approach, it successfully suppressed hydroxylation and oxidation, resulting in decreased trap states within the CQD solids while simultaneously preserving their charge transport properties. As a result, CQD SCs treated with FLA exhibited a notable improvement, achieving an open-circuit voltage of 0.66 V compared to 0.63 V in TA-treated devices, leading to an increase in power conversion efficiency from 12.71% to 13.50%.
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Affiliation(s)
- Eon Ji Lee
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
| | - Wonjong Lee
- Graduate School of Energy Science and Technology, Chungnam National University (CNU), 99, Daehak-ro, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - Tae Ho Yun
- Department of Precision Mechanical Engineering, Kyungpook National University (KNU), 2559 Gyeongsang-daero, Sangju-si, Gyeongbuk, 37224, Republic of Korea
| | - Hyung Ryul You
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
| | - Hae Jeong Kim
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
| | - Han Na Yu
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
| | - Soo-Kwan Kim
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
| | - Younghoon Kim
- Department of Applied Chemistry, Kookmin University (KMU), Seoul, 02707, Republic of Korea
| | - Hyungju Ahn
- Pohang Accelerator Laboratory (PAL), 80, Jigok-ro 127 beon-gil, Nam-gu, Gyeongsangbuk-do, Pohang-si, 37673, Republic of Korea
| | - Jongchul Lim
- Graduate School of Energy Science and Technology, Chungnam National University (CNU), 99, Daehak-ro, Yuseong-gu, Daejeon, 34134, Republic of Korea
| | - Changyong Yim
- Department of Energy Chemical Engineering, Kyungpook National University (KNU), 2559 Gyeongsang-daero, Sangju-si, Gyeongbuk, 37224, Republic of Korea
- Convergence Research Center of Mechanical and Chemical Engineering (CRCMCE), Kyungpook National University (KNU), 2559 Gyeongsang-daero, Sangju-si, Gyeongbuk, 37224, Republic of Korea
- Department of Advanced Science and Technology Convergence, Kyungpook National University (KNU), 2559 Gyeongsang-daero, Sangju-si, Gyeongbuk, 37224, Republic of Korea
| | - Jongmin Choi
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungang-Daero, Hyeonpung-Eup, Dalseong-Gun, Daegu, 42988, Republic of Korea
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Kim J, Lee Y, Nguyen VL, Thu Huong CT, Kim D, Cho K, Sung MM. Self-Organized Phase-Composite Nanocrystal Solids with Superior Charge Transport. ACS APPLIED MATERIALS & INTERFACES 2023; 15:53835-53846. [PMID: 37939291 DOI: 10.1021/acsami.3c12282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Interparticle electronic coupling is essential for self-assembled colloidal nanocrystal (NC) solid semiconductors to fulfill their wide-tunable electrical and optoelectrical properties, but it has been limited by disorders. Here, a disorder-tolerant coupling approach is presented by synthesizing self-organized NC solids based on amorphous/nanocrystalline phase-composites. The ZnO amorphous matrix, which infills the space between the less regularly ordered ZnO NCs, enables robust electronic coupling between neighboring NCs via the resonant wave function overlap, leading to a disorder-tolerant resonant conducting state. Field-effect transistors based on phase-composite semiconductors show delocalized band-like transport with superior field-effect mobility values (∼75 cm2 V-1 s-1), compared to amorphous or polycrystalline ZnO semiconductors. Furthermore, the broad amorphous matrix can mitigate interfacial defects between crystalline regions through atomic relaxation, in contrast to narrow grain boundaries in polycrystalline films, resulting in a significantly low interface trap density for phase-composite NC solids. Density function theory calculations and quantum transport simulations using the nonequilibrium Green's function formalism elucidate the origins of superior and highly disorder-tolerant electron transport in phase-composite NC solids. Our report introduces a new class of NC solids complementary to the colloidal counterpart and will be applicable to CMOS-compatible emerging device technologies.
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Affiliation(s)
- Jongchan Kim
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea
| | - Yeonghun Lee
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Electronics Engineering, Incheon National University, Incheon 22012, Republic of Korea
| | - Van Long Nguyen
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea
| | - Chu Thi Thu Huong
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea
| | - Dongwook Kim
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Kyeongjae Cho
- Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Myung Mo Sung
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea
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Nugraha MI, Indriyati I, Primadona I, Gedda M, Timuda GE, Iskandar F, Anthopoulos TD. Recent Progress in Colloidal Quantum Dot Thermoelectrics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210683. [PMID: 36857683 DOI: 10.1002/adma.202210683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/12/2023] [Indexed: 06/18/2023]
Abstract
Semiconducting colloidal quantum dots (CQDs) represent an emerging class of thermoelectric materials for use in a wide range of future applications. CQDs combine solution processability at low temperatures with the potential for upscalable manufacturing via printing techniques. Moreover, due to their low dimensionality, CQDs exhibit quantum confinement and a high density of grain boundaries, which can be independently exploited to tune the Seebeck coefficient and thermal conductivity, respectively. This unique combination of attractive attributes makes CQDs very promising for application in emerging thermoelectric generator (TEG) technologies operating near room temperature. Herein, recent progress in CQDs for application in emerging thin-film thermoelectrics is reviewed. First, the fundamental concepts of thermoelectricity in nanostructured materials are outlined, followed by an overview of the popular synthetic methods used to produce CQDs with controllable sizes and shapes. Recent strides in CQD-based thermoelectrics are then discussed with emphasis on their application in thin-film TEGs. Finally, the current challenges and future perspectives for further enhancing the performance of CQD-based thermoelectric materials for future applications are discussed.
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Affiliation(s)
- Mohamad Insan Nugraha
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), South Tangerang, Banten, 15314, Indonesia
| | - Indriyati Indriyati
- Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), South Tangerang, Banten, 15314, Indonesia
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, 40132, Indonesia
| | - Indah Primadona
- Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), South Tangerang, Banten, 15314, Indonesia
- Collaboration Research Center for Advanced Energy Materials, National Research and Innovation Agency - Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, 40135, Indonesia
| | - Murali Gedda
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Gerald Ensang Timuda
- Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), South Tangerang, Banten, 15314, Indonesia
| | - Ferry Iskandar
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, 40132, Indonesia
- Collaboration Research Center for Advanced Energy Materials, National Research and Innovation Agency - Institut Teknologi Bandung, Jl. Ganesha 10, Bandung, 40135, Indonesia
| | - Thomas D Anthopoulos
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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Liu X, Fu T, Liu J, Wang Y, Jia Y, Wang C, Li X, Zhang X, Liu Y. Solution Annealing Induces Surface Chemical Reconstruction for High-Efficiency PbS Quantum Dot Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2022; 14:14274-14283. [PMID: 35289178 DOI: 10.1021/acsami.2c01196] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Colloidal quantum dots (CQDs) have a large specific surface area and a complex surface structure. Their properties in diverse optoelectronic applications are largely determined by their surface chemistry. Therefore, it is essential to investigate the surface chemistry of CQDs for improving device performance. Herein, we realized an efficient surface chemistry optimization of lead sulfide (PbS) CQDs for photovoltaics by annealing the CQD solution with concentrated lead halide ligands after the conventional solution-phase ligand exchange. During the annealing process, the colloidal solution was used to transfer heat and create a secondary reaction environment, promoting the desorption of electrically insulating oleate ligands as well as the trap-related surface groups (Pb-hydroxyl and oxidized Pb species). This was accompanied by the binding of more conductive lead halide ligands on the CQD surface, eventually achieving a more complete ligand exchange. Furthermore, this strategy also minimized CQD polydispersity and decreased aggregation caused by conventional solution-phase ligand exchange, thereby contributing to yielding CQD films with twofold enhanced carrier mobility and twofold reduced trap-state density compared with those of the control. Based on these merits, the fabricated PbS CQD solar cells showed high efficiency of 11% under ambient conditions. Our strategy opens a novel and effective avenue to obtain high-efficiency CQD solar cells with diverse band gaps, providing meaningful guidance for controlling ligand reactivity and realizing subtly purified CQDs.
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Affiliation(s)
- Xinlu Liu
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Ting Fu
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Jianping Liu
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Yinglin Wang
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Yuwen Jia
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Chao Wang
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Xiaofei Li
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Xintong Zhang
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
| | - Yichun Liu
- Center for Advanced Optoelectronic Functional Materials Research, and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun 130024, Jilin, P. R. China
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Amadi EV, Venkataraman A, Papadopoulos C. Nanoscale self-assembly: concepts, applications and challenges. NANOTECHNOLOGY 2022; 33. [PMID: 34874297 DOI: 10.1088/1361-6528/ac3f54] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 12/02/2021] [Indexed: 05/09/2023]
Abstract
Self-assembly offers unique possibilities for fabricating nanostructures, with different morphologies and properties, typically from vapour or liquid phase precursors. Molecular units, nanoparticles, biological molecules and other discrete elements can spontaneously organise or form via interactions at the nanoscale. Currently, nanoscale self-assembly finds applications in a wide variety of areas including carbon nanomaterials and semiconductor nanowires, semiconductor heterojunctions and superlattices, the deposition of quantum dots, drug delivery, such as mRNA-based vaccines, and modern integrated circuits and nanoelectronics, to name a few. Recent advancements in drug delivery, silicon nanoelectronics, lasers and nanotechnology in general, owing to nanoscale self-assembly, coupled with its versatility, simplicity and scalability, have highlighted its importance and potential for fabricating more complex nanostructures with advanced functionalities in the future. This review aims to provide readers with concise information about the basic concepts of nanoscale self-assembly, its applications to date, and future outlook. First, an overview of various self-assembly techniques such as vapour deposition, colloidal growth, molecular self-assembly and directed self-assembly/hybrid approaches are discussed. Applications in diverse fields involving specific examples of nanoscale self-assembly then highlight the state of the art and finally, the future outlook for nanoscale self-assembly and potential for more complex nanomaterial assemblies in the future as technological functionality increases.
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Affiliation(s)
- Eberechukwu Victoria Amadi
- University of Victoria, Department of Electrical and Computer Engineering, PO BOX 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada
| | - Anusha Venkataraman
- University of Victoria, Department of Electrical and Computer Engineering, PO BOX 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada
| | - Chris Papadopoulos
- University of Victoria, Department of Electrical and Computer Engineering, PO BOX 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada
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Nugraha MI, Sun B, Kim H, El-Labban A, Desai S, Chaturvedi N, Hou Y, Garcia de Arquer FP, Alshareef HN, Sargent EH, Baran D. Dopant-Assisted Matrix Stabilization Enables Thermoelectric Performance Enhancement in n-Type Quantum Dot Films. ACS APPLIED MATERIALS & INTERFACES 2021; 13:18999-19007. [PMID: 33856780 DOI: 10.1021/acsami.1c01886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Efficient thermoelectric generators require further progress in developing n-type semiconductors that combine low thermal conductivity with high electrical conductivity. By embedding colloidal quantum dots (CQDs) in a metal halide matrix (QDMH), the metal halide matrix can enhance phonon scattering, thus suppressing thermal transport; however, simultaneously achieving high electrical conductivity in such systems has previously been limited by the deleterious impact of a large density of interfaces on charge transport. Therefore, new strategies are needed to improve charge carrier transport without sacrificing matrix-enabled low thermal transport. Here, we report the use of chemical doping in the solution state to improve electron transport while maintaining low thermal transport in QDMH films. By incorporating cesium carbonate (Cs2CO3) salts as a dopant prior to matrix formation, we find that the dopant stabilizes the matrix in colloidal inks and enables efficient n-type doping in QDMH films. As a result, this strategy leads to an enhanced n-type thermoelectric behavior in solution-processed QDMH films near room temperature, with a thermal conductivity of 0.25 W m-1 K-1-significantly lower than in prior films based on organic-ligand-cross-linked CQD films (>0.6 W m-1 K-1) and spark-plasma-sintered CQD systems (>1 W m-1 K-1). This study provides a pathway to developing efficient n-type thermoelectric materials with low thermal conductivity using single-step deposition and low-temperature processing.
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Affiliation(s)
- Mohamad Insan Nugraha
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Bin Sun
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - Hyunho Kim
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Abdulrahman El-Labban
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Saheena Desai
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Neha Chaturvedi
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Yi Hou
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - F Pelayo Garcia de Arquer
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - Husam N Alshareef
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada
| | - Derya Baran
- Physical Science and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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Ahmad W, Gong Y, Abbas G, Khan K, Khan M, Ali G, Shuja A, Tareen AK, Khan Q, Li D. Evolution of low-dimensional material-based field-effect transistors. NANOSCALE 2021; 13:5162-5186. [PMID: 33666628 DOI: 10.1039/d0nr07548e] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Field-effect transistors (FETs) have tremendous applications in the electronics industry due to their outstanding features such as small size, easy fabrication, compatibility with integrated electronics, high sensitivity, rapid detection and easy measuring procedures. However, to meet the increasing demand of the electronics industry, efficient FETs with controlled short channel effects, enhanced surface stability, reduced size, and superior performances based on low-dimensional materials are desirable. In this review, we present the developmental roadmap of FETs from conventional to miniaturized devices and highlight their prospective applications in the field of optoelectronic devices. Initially, a detailed study of the general importance of bulk and low-dimensional materials is presented. Then, recent advances in low-dimensional material heterostructures, classification of FETs, and the applications of low-dimensional materials in field-effect transistors and photodetectors are presented in detail. In addition, we also describe current issues in low-dimensional material-based FETs and propose potential approaches to address these issues, which are crucial for developing electronic and optoelectronic devices. This review will provide guidelines for low-dimensional material-based FETs with high performance and advanced applications in the future.
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Affiliation(s)
- Waqas Ahmad
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Youning Gong
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Ghulam Abbas
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Karim Khan
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Maaz Khan
- Nanomaterials Research Group, Physics Division, PINSTECH, Nilore 45650, Islamabad, Pakistan
| | - Ghafar Ali
- Nanomaterials Research Group, Physics Division, PINSTECH, Nilore 45650, Islamabad, Pakistan
| | - Ahmed Shuja
- Centre for Advanced Electronics & Photovoltaic Engineering, International Islamic University, Islamabad, Pakistan
| | - Ayesha Khan Tareen
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Qasim Khan
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Delong Li
- Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, P. R. China.
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