Luminescent Solar Concentrators (LSCs)

Project Title: End-to-end performance analysis of 3D printed luminescent solar concentrators

Project Dates: October 2019 - September 2020

Collaborators: Anne Richter, Bolong Zhang, Mike Bennison

Location: Functional Photoactive Materials Laboratory, University of Cambridge

Project Summary:

In recent years, there has been increasing urgency to develop cheap, efficient solar devices. However, most solar modules are large, bulky, and rectangular, making integration into the built environment non-trivial. A promising technological solution that may help solve this problem is the luminescent solar concentrator (LSC). A typical LSC is a plastic slab that absorbs sunlight and re-emits light of a tailored wavelength towards its edges, where solar cells can be installed. Because LSCs are colorful, semi-transparent, and modular, they hold great potential in reducing the cost and barrier to entry of solar technologies. However, they suffer from significant optical losses limiting their efficiency. Many novel device shapes have been proposed to improve light transport pathways in LSCs, but these often rely on expensive or wasteful fabrication techniques.

A potential solution to this is 3D printing, which has gained immense traction as an alternative manufacturing technology. 3D printing has many benefits including accessibility, rapid prototyping, and fabrication of completely new designs. This study presents an end-to-end performance analysis methodology to evaluate new LSC designs that can take advantage of this novel manufacturing technology. This methodology is applied to preliminary 3D printed parts as a proof of concept that can be applied to a wider variety of designs.

This study consists of 3 distinct steps: simulating the optical efficiency of the printed part, 3D printing the part with luminescent filament, and characterizing its optical efficiency experimentally.

Simulation of LSCs using ray tracing has been extensively investigated in the past; however, this has been limited to conventional, rectangular LSCs. Analyzing the performance of alternative LSC geometries requires developing a novel methodology for evaluating device efficiency, as well as implementing parallelization techniques to reduce computation time for complex geometries.

Among the 3D printing technologies, fused deposition modeling (FDM) is the most accessible and widely used, but it is not known for producing transparent parts usable for optical applications. This thesis aims to solve some of the complications of FDM to develop a cheap, rapid, and accessible methodology for printing efficient LSCs.

Similar to modeling, device characterization has been limited to rectangular LSCs, so a standardized methodology for evaluating device efficiency has been developed, allowing for comparison between different device shapes.

The simulated results of this study indicate 3D printed devices have the potential to offer a twofold increase in efficiency over conventionally manufactured bulk devices. Actual 3D printed devices were measured to have similar efficiency to bulk devices (within 1%), but extrapolating the results to parts made with higher quality material also suggests some parts would have twice the efficiency of their bulk counterparts. 3D printed parts may have additional benefits in improving directionality of edge-emitted light, but this will have to be confirmed in future work.

Overall, 3D printing provides major benefits over conventional manufacturing techniques, as it introduces rapid prototyping by allowing experimental iteration and model validation, allows custom-built designs for easier integration into the built environment, and increases the optical efficiency of devices by improving light transport pathways. With further development, this technology can help make widespread solar adoption a reality.

Full thesis available here!