Dye alignment in luminescent solar concentrators: I. Vertical alignment for improved waveguide coupling.

Area of Science:

• Materials Science
• Renewable Energy
• Optics

Background:

• Luminescent solar concentrators (LSCs) capture solar radiation using embedded dyes within a waveguide.
• Photon loss occurs when re-emitted light escapes the waveguide, limiting LSC efficiency.
• Optimizing light re-emission into waveguide modes is crucial for efficient solar energy conversion.

Purpose of the Study:

• To improve the fundamental efficiency limit of luminescent solar concentrators (LSCs).
• To investigate the impact of controlled dye molecule orientation on waveguide trapping efficiency.
• To explore the use of liquid crystalline hosts for dye alignment in LSCs.

Main Methods:

• Developed a theoretical model correlating waveguide trapping efficiency with dye dipole orientation.
• Fabricated LSCs using a liquid crystalline host to align dye molecules.
• Measured trapping efficiency for aligned and unaligned dye configurations.

Main Results:

• Achieved a significant increase in waveguide trapping efficiency from 66% (no alignment) to 81% (vertical dye alignment).
• Demonstrated that enhanced trapping efficiency is maintained for geometric gains up to 30.
• Confirmed that an external diffuser can mitigate weak absorption issues in vertically-aligned LSCs.

Conclusions:

• Controlling dye molecule orientation via liquid crystals is a viable strategy to enhance LSC performance.
• Vertically aligned dyes in LSCs offer a pathway to overcome fundamental efficiency limitations.
• Further optimization of LSC design with aligned dyes holds promise for improved solar energy harvesting.