Shining Light on Limits: Luminescent Solar Concentrators as Power Generating Windows

INTRODUCTION In the future, more and more people will live in cities, while the space for renewable energy in urban areas is scarce. As a result, there is a strong need for renewable energy generation technologies that double as a building element to sustainably supply our future cities. A promising technology is the luminescent solar concentrator (LSC), which is a type of transparent solar panel. The LSC can function as a window while at the same time generating renewable electricity. The LSC uses luminescent particles to absorb and emit sunlight, which is guided through the window glass to solar cells attached at the sides. This leads to a trade-off between the transmitted light necessary for functioning as a window and the absorbed light necessary to generate electricity. RESEARCH QUESTIONS The main question research question is: "Is it possible to develop efficient, transparent, and durable luminescent solar concentrators to replace conventional windows?" For LSCs to function as a window, they need to be sufficiently transparent while being efficient enough to generate a significant amount of electricity. Furthermore, they need to be able to maintain this power output for a long period of time in an outdoor environment. In this thesis, these requirements are investigated in six chapters that broadly cover the following three topics. Chapter 2 and 3: The viability of tandem configurations is explored, i.e., the stacking of two different LSCs, and the maximum theoretical efficiency of LSCs is researched. Chapter 4 and 5: A novel algorithm that is much quicker than previous algorithms is introduced. The algorithm calculates the maximum efficiency based on existing LSC data from the scientific literature. Chapter 6 and 7: The performance of LSCs during and after two years in an outdoor environment is presented. The results from chapters two to seven provide the answer to the main research question. RESULTS The results based on the six chapters: Chapters 2 and 3: Tandem configurations are feasible but do not lead to significantly better performances for the tested luminophores. The maximum theoretical power conversion efficiency for a luminescent solar concentrator that functions as a window is around 10%. Chapters 4 and 5: The maximum power conversion efficiency for window-appropriate LSCs based on currently existing luminophores is around 1%. Chapters 6 and 7: LSCs in an outdoor environment perform well over a full day, showing consistent performance for sunny and cloudy days and can remain stable after two years. CONCLUSION AND DISCUSSION Based on chapters two and three and chapters six and seven, the LSC can theoretically have an efficiency of 10%, and it can remain stable for more than two years in an outdoor environment. However, based on chapters four and five, the currently feasible efficiency for an LSC that can function as a window is around 1%. As a result, the answer to the research question is that durable and transparent LSCs are feasible but with a maximum efficiency of 1%. Future research should focus on improved LSCs and alternative applications, e.g., in agriculture.