Luminescent solar concentrator efficiency enhanced via nearly lossless propagation pathways

Luminescent solar concentrators (LSCs) have the potential to serve as energy-harvesting windows in buildings. Although recent advances in nanotechnology have led to the emergence of novel fluorophores such as quantum dots, perovskites and others, the commercialization of such functional glass remains immature due to an insufficient power conversion efficiency. In other words, improvements in fluorophores alone cannot fully maximize the potential of LSCs. Here we introduce a new laminated type of LSC structure where a patterned low-refractive-index medium acts as an optical 'guard rail', providing a practically non-decaying path for guiding photons. We also propose the design rules regarding the dimensions of LSCs and the spectral characteristics of fluorophores. Once these rules were applied, we achieved record-high LSC performance. The measured external quantum efficiencies at 450 nm are 45% for a 100 cm2 area and 32% for the LSC with an edge aspect ratio of 71. The device efficiency is 7.6%, the highest value ever reported, to the best of our knowledge. These findings may have industrial implications and could accelerate the commercialization of LSCs. Luminescence solar concentrators are improved by using a laminated structure that creates a practically non-decaying optical 'guard rail' for light. Design rules enabled external quantum efficiencies as high as 45% for 450 nm light, yielding a device efficiency of 7.6%, probably useful for energy-harvesting windows.