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Terpenes for Use in OLEDs

Lance Griffin
Written by Lance Griffin

Organic light-emitting diodes (OLEDs) are LEDs that make use of an organic (carbon-based) film. Electrodes deliver current to the semiconductor film, and the organic material emits diffuse light. OLEDs are a significant innovation with the potential to transform technology, and terpenes may become key materials in the construction of OLED devices.

OLEDs are ultra-thin and may be flexible and transparent. OLEDs match the efficiency of LED lights without producing glare and intense brightness. They are an attractive option for technological displays. The Samsung A8 and iPhone X are examples of mobile phones with OLED displays. The television company LG offers TVs with different styles of OLED screens (e.g., flat, curved, and wallpaper). OLEDs may also be utilized to develop cutting-edge healthcare devices; microscopic OLEDs can illuminate and modulate biological cells at high resolution. [1]

Nonetheless, the US Department of Energy reports that “innovations are still needed on multiple fronts to increase the efficiency, lifetime, and light output of OLED devices.” Materials that facilitate charge are one challenge; they are often synthetic, non-renewable, and susceptible to chemical degradation. [2,3] Early OLED lights and television sets were known to suffer dark spots, for example, due to dust, oxygen, and moisture contact. [4]

Terpenes are organic, ubiquitous, environmentally-friendly hydrocarbons that OLED device manufacturers may consider implementing for different purposes. A recent study in 2019 determined that flawless thin films could be made from D-limonene derived from waste orange peels quickly and easily. [5]

Individual terpene chemistry appears to influence conduction properties. In one study, linalyl acetate (the acetate ester of linalool) was tested as a polymer thin film and demonstrated electrical transport attributes on par with conventional insulating materials. [6] Polyterpenol thin film (from non-synthetic terpenol), on the other hand, blocks electrons while allowing hole transport. It therefore acts as a rectifier, meaning it converts bidirectional alternating current (AC) into unidirectional direct current (DC). [7] Steady DC voltages are necessary for most electronics.

In an investigation published in Scientific Reports, researchers probed the dielectric attributes of cis−β−ocimene thin films. They also tested degradation in aqueous settings; specifically, they examined biocompatibility with simulated body fluid, actual human leukemia cells, and mouse macrophage cells. The films were transparent, smooth, and free of defects; the dielectric constant of 3.5-3.6 (1kHz) was maintained in all aqueous conditions and up to 200 ° C. The researchers conclude that cis−β−ocimene thin films may be successfully used in biomedical OLED devices. [2]

OLED applications are complex; the technology brings together chemistry, physics, electrical engineering, material science, and design. [3] Emerging research suggests that terpenes may have a role to play in this application yet.

References
1. Steude, Anja, et al. “Arrays of Microscopic Organic LEDs for High-Resolution Optogenetics.” Science Advances, vol. 2, no. 5, 2016, doi:10.1126/sciadv.1600061. Journal Impact Factor = 11.51 Times Cited = 15 (Web of Science)
2. Bazaka, Kateryna, et al. “Plant-Derived Cis-β-Ocimene as a Precursor for Biocompatible,
Transparent, Thermally-Stable Dielectric and Encapsulating Layers for Organic Electronics.” Scientific Reports, vol. 6, no. 1, 2016, doi:10.1038/srep38571. Journal Impact Factor = 4.122 Times Cited = 4 (Nature)
3. Gaspar, Daniel J, and Evgueni Polikarpov. “Introduction.” OLED Fundamentals: OLED Fundamentals: Materials, Devices, and Processing of Organic Light-Emitting Diodes, CRC Press, 2015, pp. 1–4. Google Books
4. Schaer, M., et al. “Water Vapor and Oxygen Degradation Mechanisms in Organic Light Emitting Diodes.” Advanced Functional Materials, vol. 11, no. 2, 2001, pp. 116–121., doi:10.1002/1616-3028(200104)11:2<116::aid-adfm116>3.3.co;2-2. Journal Impact Factor = 13.325 Times Cited = 145 (ResearchGate)
5. Gerchman, D., et al. “Thin Film Deposition by Plasma Polymerization Using d-Limonene as a Renewable Precursor.” Progress in Organic Coatings, vol. 129, 2019, pp. 133–139., doi:10.1016/j.porgcoat.2019.01.018. Journal Impact Factor = 2.995
6. Anderson, L.J., and M.V. Jacob. “Temperature Dependent Electrical Impedance Spectroscopy Measurements of Plasma Enhanced Chemical Vapour Deposited Linalyl Acetate Thin Films.” Thin Solid Films, vol. 534, 2013, pp. 452–458., doi:10.1016/j.tsf.2013.02.015. Journal Impact Factor = 1.939 Times Cited = 5 (ResearchGate)
7. Jacob, Mohan V., et al. “Electron-Blocking Hole-Transport Polyterpenol Thin Films.” Chemical Physics Letters, vol. 528, 2012, pp. 26–28., doi:10.1016/j.cplett.2012.01.031. Journal Impact Factor = 1.686 Times Cited = 23 (ResearchGate)

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Lance Griffin

Lance Griffin

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