UC Merced

Solar energy is a prominent renewable source of electricity if cheap methods are designed for its concentration and conversion. With the purpose of improving power conversion efficiency and lowering the cost, luminescent solar concentrations (LSCs) are developed for collecting and concentrating both direct and diffuse light for Photovoltaic systems without tracking. Nano-structured near infrared PbS quantum dots (QDs) as new luminescent materials are identified. This material is optically characterized by using steady state spectroscopic technologies and electrically characterized by outdoor testing. These properties are also compared with visible CdSe/ZnS QDs for LSC PV systems and organic dye LSC PV systems. The results show the promising future of near infrared QDs as luminescent material for LSCs if their stability can be properly controlled. Techniques for fabrication and characterization of LSCs as "smart" windows are developed. A range of prototypes are fabricated, optically and electrically characterized. A variety of optimal designs for improving the output power conversion efficiency are investigated both for QDs LSCs and for organic dye LSCs. For LSCs with organic dyes, the size dependent optimization methods are developed for both one layer and stacked structures. The largest fabricated prototype has 60cm by 120cm by 0.32cm. It yields electric gain 4.23, which is much larger than that of fixed concentrators based on geometrical optics. Prototypes fabricated with new outdoor use organic laser dyes show the same electric gain but with 5.88x smaller in size 2.67x larger in optical efficiency. This results show that LSCs fabricated with outdoor use organic dyes are very promising if applied into stacked structures. New generation LSCs with liquid crystals as matrix materials are explored. Properties of liquid crystals and dyes for the new generation LSCs are analyzed with the predicted theoretical improvement for trapping efficiency up to 21.3%. Such anisotropic LSCs containing identified organic dyes are successfully fabricated and optically characterized. Performances of these LSCs are compared with isotropic samples.