1. InGaN solar cells show promise for concentrated photovoltaic applications Jingyu Lin, Texas Tech University, DMR 0906879 InGaN alloys recently emerge as a new solar cell materials system due to their tunable energy band gaps varying from 0.7 eV for InN to 3.4 eV for GaN, covering almost the whole solar spectrum. One could obtain a photovoltaic cell that could achieve better than 50% solar energy conversion by using InGaN alloys up to 40% indium fraction. Unfortunately these remain theoretical hopes because it is very difficult to grow high-quality InGaN with high indium contents. The material quality of InGaN severely degrades due to phase separation and inhomogeneity of solid solution as indium content and layer thickness increase. Utilizing the idea of suppressing phase separation by strain engineering, we demonstrated the operation of In x Ga 1- x N/GaN multiple quantum well solar cells. The conversion power efficiency of 2.95% still falls short of the ~8% theoretical maximum of a single junction cell at this optical energy band gap, but is a significant improvement over previously reported values for InGaN based solar cells. The conversion efficiency was found to increase under concentrated sunlight and the results revealed strong potential of InGaN-based quantum well solar cells for concentrated photovoltaic applications. R. Dahal et al, Appl. Phys. Lett., 97, 073115 (2010)

2. PIs work with undergraduate students to help them learn the physical and engineering principles of solar cells, solid state detectors, and light emitting diodes. Students learned to construct portable and self-sustainable light sources, energy efficiency product, or a UV radiation monitoring package. Bridging the Miscibility Gap in InGaN Alloys Jingyu Lin, Texas Tech University, DMR 0906879

3. Jingyu Lin, Texas Tech University, DMR 0906879