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Recent Progress on Graphene Flexible Photodetectors. MATERIALS 2022; 15:ma15144820. [PMID: 35888288 PMCID: PMC9318373 DOI: 10.3390/ma15144820] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/18/2022] [Accepted: 06/29/2022] [Indexed: 01/02/2023]
Abstract
In recent years, optoelectronics and related industries have developed rapidly. As typical optoelectronics devices, photodetectors (PDs) are widely applied in various fields. The functional materials in traditional PDs exhibit high hardness, and the performance of these rigid detectors is thus greatly reduced upon their stretching or bending. Therefore, the development of new flexible PDs with bendable and foldable functions is of great significance and has much interest in wearable, implantable optoelectronic devices. Graphene with excellent electrical and optical performance constructed on various flexible and rigid substrates has great potential in PDs. In this review, recent research progress on graphene-based flexible PDs is outlined. The research states of graphene conductive films are summarized, focusing on PDs based on single-component graphene and mixed-structure graphene, with a systematic analysis of their optical and mechanical performance, and the techniques for optimizing the PDs are also discussed. Finally, a summary of the current applications of graphene flexible PDs and perspectives is provided, and the remaining challenges are discussed.
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Ali A, Kim SY, Hussain M, Jaffery SHA, Dastgeer G, Hussain S, Anh BTP, Eom J, Lee BH, Jung J. Deep-Ultraviolet (DUV)-Induced Doping in Single Channel Graphene for Pn-Junction. NANOMATERIALS 2021; 11:nano11113003. [PMID: 34835767 PMCID: PMC8623685 DOI: 10.3390/nano11113003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 11/24/2022]
Abstract
The electronic properties of single-layer, CVD-grown graphene were modulated by deep ultraviolet (DUV) light irradiation in different radiation environments. The graphene field-effect transistors (GFETs), exposed to DUV in air and pure O2, exhibited p-type doping behavior, whereas those exposed in vacuum and pure N2 gas showed n-type doping. The degree of doping increased with DUV exposure time. However, n-type doping by DUV in vacuum reached saturation after 60 min of DUV irradiation. The p-type doping by DUV in air was observed to be quite stable over a long period in a laboratory environment and at higher temperatures, with little change in charge carrier mobility. The p-doping in pure O2 showed ~15% de-doping over 4 months. The n-type doping in pure N2 exhibited a high doping effect but was highly unstable over time in a laboratory environment, with very marked de-doping towards a pristine condition. A lateral pn-junction of graphene was successfully implemented by controlling the radiation environment of the DUV. First, graphene was doped to n-type by DUV in vacuum. Then the n-type graphene was converted to p-type by exposure again to DUV in air. The n-type region of the pn-junction was protected from DUV by a thick double-coated PMMA layer. The photocurrent response as a function of Vg was investigated to study possible applications in optoelectronics.
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Affiliation(s)
- Asif Ali
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
| | - So-Young Kim
- Center for Semiconductor Technology Convergence, Department of Electrical Engineering, Pohang University of Science and Technology, Cheongam-ro 77, Nam-gu, Pohang 37673, Korea; (S.-Y.K.); (B.H.L.)
| | - Muhammad Hussain
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
| | - Syed Hassan Abbas Jaffery
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
| | - Ghulam Dastgeer
- Department of Physics & Astronomy, Graphene Research Institute-Texas Photonics Center International Research Center (GRI–TPC IRC), Sejong University, Seoul 05006, Korea; (G.D.); (J.E.)
| | - Sajjad Hussain
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
| | - Bach Thi Phuong Anh
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
| | - Jonghwa Eom
- Department of Physics & Astronomy, Graphene Research Institute-Texas Photonics Center International Research Center (GRI–TPC IRC), Sejong University, Seoul 05006, Korea; (G.D.); (J.E.)
| | - Byoung Hun Lee
- Center for Semiconductor Technology Convergence, Department of Electrical Engineering, Pohang University of Science and Technology, Cheongam-ro 77, Nam-gu, Pohang 37673, Korea; (S.-Y.K.); (B.H.L.)
| | - Jongwan Jung
- HMC (Hybrid Materials Center), Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 05006, Korea; (A.A.); (M.H.); (S.H.A.J.); (S.H.); (B.T.P.A.)
- Correspondence:
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Park S, Kim HR, Kim J, Hong BH, Yoon HJ. Enhanced Thermopower of Saturated Molecules by Noncovalent Anchor-Induced Electron Doping of Single-Layer Graphene Electrode. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103177. [PMID: 34453364 DOI: 10.1002/adma.202103177] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/22/2021] [Indexed: 06/13/2023]
Abstract
Enhancing thermopower is a key goal in organic and molecular thermoelectrics. Herein, it is shown that introducing noncovalent contact with a single-layer graphene (SLG) electrode improves the thermopower of saturated molecules as compared to the traditional gold-thiolate covalent contact. Thermoelectric junction measurements with a liquid-metal technique reveal that the value of Seebeck coefficient in large-area junctions based on n-alkylamine self-assembled monolayers (SAMs) on SLG is increased up to fivefold compared to the analogous junction based on n-alkanethiolate SAMs on gold. Experiments with Raman spectroscopy and field-effect transistor analysis indicate that such enhancements benefit from the creation of new in-gap states and electron doping through noncovalent interaction between the amine anchor and the SLG electrode, which leads to a reduced energy offset between the Fermi level and the transport channel. This work demonstrates that control of interfacial bonding nature in molecular junctions improves the Seebeck effect in saturated molecules.
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Affiliation(s)
- Sohyun Park
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
| | - Hwa Rang Kim
- Department of Chemistry, Seoul National University, Seoul, 08826, South Korea
| | - Juhee Kim
- Department of Chemistry, Seoul National University, Seoul, 08826, South Korea
| | - Byung-Hee Hong
- Department of Chemistry, Seoul National University, Seoul, 08826, South Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul, 02841, South Korea
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