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Zarei M, Li M, Medvedeva EE, Sharma S, Kim J, Shao Z, Walker SB, LeMieux M, Liu Q, Leu PW. Flexible Embedded Metal Meshes by Sputter-Free Crack Lithography for Transparent Electrodes and Electromagnetic Interference Shielding. ACS APPLIED MATERIALS & INTERFACES 2024; 16:6382-6393. [PMID: 38279914 PMCID: PMC10859897 DOI: 10.1021/acsami.3c16405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/14/2024] [Accepted: 01/14/2024] [Indexed: 01/29/2024]
Abstract
A facile and novel fabrication method is demonstrated for creating flexible poly(ethylene terephthalate) (PET)-embedded silver meshes using crack lithography, reactive ion etching (RIE), and reactive silver ink. The crack width and spacing in a waterborne acrylic emulsion polymer are controlled by the thickness of the polymer and the applied stress due to heating and evaporation. Our innovative fabrication technique eliminates the need for sputtering and ensures stronger adhesion of the metal meshes to the PET substrate. Crack trench depths over 5 μm and line widths under 5 μm have been achieved. As a transparent electrode, our flexible embedded Ag meshes exhibit a visible transmission of 91.3% and sheet resistance of 0.54 Ω/sq as well as 93.7% and 1.4 Ω/sq. This performance corresponds to figures of merit (σDC/σOP) of 7500 and 4070, respectively. For transparent electromagnetic interference (EMI) shielding, the metal meshes achieve a shielding efficiency (SE) of 42 dB with 91.3% visible transmission and an EMI SE of 37.4 dB with 93.7% visible transmission. We demonstrate the highest transparent electrode performance of crack lithography approaches in the literature and the highest flexible transparent EMI shielding performance of all fabrication approaches in the literature. These metal meshes may have applications in transparent electrodes, EMI shielding, solar cells, and organic light-emitting diodes.
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Affiliation(s)
- Mehdi Zarei
- Department
of Mechanical Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Mingxuan Li
- Department
of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Elizabeth E. Medvedeva
- Department
of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Sooraj Sharma
- Department
of Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Jungtaek Kim
- Department
of Industrial Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Zefan Shao
- Department
of Mechanical Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - S. Brett Walker
- Electroninks
Incorporated, Austin, Texas 78744, United States
| | - Melbs LeMieux
- Electroninks
Incorporated, Austin, Texas 78744, United States
| | - Qihan Liu
- Department
of Mechanical Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Paul W. Leu
- Department
of Mechanical Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department
of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department
of Industrial Engineering, University of
Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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Zarei M, Loy JC, Li M, Zhou Z, Sinha S, LeMieux M, Walker SB, Rand BP, Leu PW. Substrate-embedded metal meshes for ITO-free organic light emitting diodes. OPTICS EXPRESS 2023; 31:34697-34707. [PMID: 37859220 DOI: 10.1364/oe.499932] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/01/2023] [Indexed: 10/21/2023]
Abstract
Organic light-emitting diodes (OLEDs) have great potential for use in large-area display and lighting applications, but their widespread adoption for large areas is hindered by the high cost and insufficient performance of indium tin oxide (ITO) anodes. In this study, we introduce an alternative anode material - a silver mesh embedded in glass - to facilitate production of large-area OLEDs. We present a facile, scalable manufacturing technique to create high aspect ratio micromeshes embedded in glass to provide the planar geometry needed for OLED layers. Our phosphorescent green OLEDs achieve a current efficiency of 51.4 cd/A at 1000 cd/m2 and reach a slightly higher external quantum efficiency compared to a standard ITO/glass reference sample. Notably, these advancements are achieved without any impact on the viewing angle of the OLEDs. These findings represent a promising advancement towards ITO-free, high-efficiency OLEDs for various high performance, large-area applications, such as lighting and displays.
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Huo N, Tenhaeff WE. High Refractive Index Polymer Thin Films by Charge-Transfer Complexation. Macromolecules 2023; 56:2113-2122. [PMID: 36938507 PMCID: PMC10019454 DOI: 10.1021/acs.macromol.2c02532] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/19/2023] [Indexed: 03/06/2023]
Abstract
High refractive index polymers are essential in next-generation flexible optical and optoelectronic devices. This paper describes a simple synthetic method to prepare polymeric optical coatings possessing high refractive indexes. Poly(4-vinylpyridine) (P4VP) thin films prepared using initiated chemical vapor deposition are exposed to highly polarizable halogen molecules to form stable charge-transfer complexes: P4VP-IX (X = I, Br, and Cl). Fourier transform infrared spectroscopy was used to confirm the formation of charge-transfer complexes. Characterized by spectroscopic ellipsometry, the maximum refractive index of 2.08 at 587.6 nm is obtained for P4VP-I2. For P4VP-IBr and P4VP-ICl, the maximum refractive indexes are 1.849 and 1.774, respectively. By controlling the concentration of charge-transfer complexes, either through the halogen incorporation step or polymer composition through copolymerization with ethylene glycol dimethacrylate, the refractive indexes of the polymer thin films can be precisely controlled. The feasibility of P4VP-IX materials as optical coatings is also explored. The refractive index and thickness uniformity of a P4VP-I2 film over a 10 mm diameter circular area were characterized, showing standard deviations of 0.0769 and 1.91%, respectively.
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