LSCs for Displays and Energy Harvesting

Article in Journal of Photonics for Energy on luminescent solar concentrators.

01 July 2017
energy harvesting

Researchers at Ritsumeikan University (Japan) have successfully conducted a proof-of-concept experiment that employs a luminescent solar concentrator (LSC) to harvest energy from ambient light as well as display high-resolution images.

The researchers describe the development, processes, and applications for replacing the phosphor screen in a laser phosphor display (LPD) with an LSC in a recent article published in the Journal of Photonics for Energy.

In “Energy-harvesting laser phosphor display and its design considerations,” SPIE member Ichiro Fujieda and his colleagues at Ritsumeikan University (Japan) fabricated a 95 × 95 × 10 mm screen by sandwiching a thin layer of coumarin 6 with two transparent plates. These plates guided the photoluminescent (PL) photons emitted in both directions toward their edge surfaces.

After removing the light source in a commercial grade projector using digital micromirror device technology and feeding a blue laser beam into its optics, the screen generated green images.

Attaching a photodiode with a 10 × 10 mm sensitive area on the bottom edge of the screen to record the power of the PL photons indicated that a fully covered version would harvest up to 71% of the incoming optical power. However, a ghost image was noticeable when displaying a high-contrast still image.

A resolution test chart displayed on a phosphor screen, from Journal of Photonics for Energy.

Fujieda and coauthors Shunsuke Itaya, Masamichi Ohta, Yuuki Hirai, and Takamasa Kohmoto addressed two important design considerations.

First, tiling small modules and extracting the PL photons in each module reduces the thickness of a large-area system and alleviates the effect of self-absorption. For seamless tiling, attaching an output coupler to the wave guiding plate and mounting solar cells provides an optimal solution.

Second, the origin of the ghost image is the PL photons reflecting at the interface between the rear plate and the outside environment. By reducing the thickness of the rear plate on the LPD, they were able to eliminate this optical cross talk between pixels.

Loucas Tsakalakos, associate editor for the Journal of Photonics for Energy, called the study “a unique and novel application of a luminescent solar concentrator for display applications.”

He said the work shows practical operation of such a device, “describes the basic operational principle and expected energy-harvesting capability of such a system, and describes ways of improving the design in future work.”


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