High-efficiency light emission by means of exciton–surface-plasmon coupling

• Published in: Journal of photochemistry and photobiology. C, Photochemistry reviews Photochemistry reviews, 2017-09, Vol.32, p.58-77
• Main Authors: Okamoto, Koichi, Funato, Mitsuru, Kawakami, Yoichi, Tamada, Kaoru
• Format: Article
• Language: English
• Subjects: Coupling; Efficiency; Exciton; Excitons; Fluorescence; Gallium nitrides; Indium gallium nitrides; LEDs; Light emission; Light emitting diodes; Light sources; Organic light emitting diodes; Photocatalysis; Photochemistry; Plasmonics; Plasmons; Quantum wells; Spontaneous emission; Surface plasmon
• ISSN: 1389-5567; 1873-2739
• DOI: 10.1016/j.jphotochemrev.2017.05.005

[Display omitted] •A brief history and underlying mechanism of the surface-plasmon (SP)-enhanced light emissions were presented.•Enhancements of the spontaneous emission rates of the excited states were discussed by the terms of the coupling states between an exciton and SP.•Recent progress and current problems regarding device applications of plasmonic light-emitting diodes (LEDs) were reviewed.•Future possibilities of SP-enhanced light emissions were discussed to extend the wavelength regions from deep ultraviolet (UV) to infrared (IR). Coupling between surface plasmons (SPs) and excitons can be used to enhance the emission efficiencies of light-emitting materials and devices. This approach had been theoretically predicted and, in 2004, was experimentally demonstrated by our group for enhancing the visible emission from InGaN/GaN quantum wells (QWs). Exciton–SP coupling increases the spontaneous emission rates of the excited states, causes a relative reduction in nonradiative relaxation, and ultimately increases the internal quantum efficiencies (IQEs) of such devices. Here, we present a brief history of the increases in emission efficiency that have been achieved and the underlying mechanism thereof. This method has the potential to enable the development of high-efficiency light-emitting diodes (LEDs), eventually leading to the replacement of fluorescent lights with solid-state light sources. After the initial discovery of this phenomenon, many device structures were proposed and reported; however, their emission efficiencies have thus far remained insufficient for practical application. Here, we also present recent progress on device applications and the current problems that must be solved. Finally, we explain the future possibilities regarding the extension of SP-enhanced light emission over a broader wavelength region, from the deep ultraviolet (UV) to the infrared (IR).