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A compound parabolic concentrator (CPC) is proposed to mix light from RGBW LEDs. The designed CPC with an overall length of 49.6 mm and a concentration ratio of 17.3 achieves the efficiency of 95.2% in simulation. The proposed module has the merits of high efficiency and low cost.

This research involves a simple and high concentration simulation design for a passive solar lighting system. This system incorporates the technology and optical design that are required for the collection and emission of sunlight for solar lighting. Several pieces of Plano-convex lens are placed in a specific geometric arrangement, so that without a solar tracking system, parallel light emitted by the sun at different times can be collected. The light can then be focused via lenses and internally transmitted through optical fibers and ultimately be transmitted to the emission element. This system is expected to be used as a reference for sufficient lighting for indoor rooms and toilets in a building whether in the morning or afternoon on a sunny day.

A light-mixing module consisting of a compound parabolic concentrator (CPC) and a fiber for mixing light from red, green, blue, and white (RGBW) LEDs was proposed. The design principle was investigated and a design prototype was demonstrated in a simulation. The simulated results showed that the chromatic nonuniformity was reduced to 1/10 when the fiber length was 40 times the core width, and the module efficiencies were more than 80% and more than 60% when the fiber lengths were 350 mm and 5 m, respectively. The proposed module is suitable for solar lighting compensation or indoor lighting, such as plant-factory lighting.

Biomimetic nanostructures have shown to enhance the optical absorption of Ga(0.5)In(0.5)P/GaAs/Ge triple junction solar cells due to excellent antireflective (AR) properties that, however, are highly dependent on their geometric dimensions. In practice, it is challenging to control fabrication conditions which produce nanostructures in ideal periodic arrangements and with tapered side-wall profiles, leading to sacrificed AR properties and solar cell performance. In this work, we introduce compound biomimetic nanostructures created by depositing a layer of silicon dioxide (SiO(2)) on top of titanium dioxide (TiO(2)) nanostructures for triple junction solar cells. The device exhibits photogenerated current and power conversion efficiency that are enhanced by ~8.9% and ~6.4%, respectively, after deposition due to their improved antireflection characteristics. We further investigate and verify the optical properties of compound structures via a rigorous coupled wave analysis model. The additional SiO(2) layer not only improves the geometric profile, but also serves as a double-layer dielectric coating. It is concluded that the compound biomimetic nanostructures exhibit superior AR properties that are relatively insensitive to fabrication constraints. Therefore, the compound approach can be widely adopted for versatile optoelectronic devices and applications.