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II2.03 - Light Trapping Structures Fabricated by Low Cost and Scalable Techniques 
April 22, 2014   2:15pm - 2:30pm

Light management schemes have known a steady development in the past decade as a solution envisioned to enhance the performance of optical and optoelectronic systems. However, to avoid additional processing costs, it is important to propose simple and scalable fabrication techniques to integrate such schemes within functional devices. In this project, we demonstrate highly efficient and tunable light trapping structures prepared using simple and scalable Sol-Gel chemistry, spin coating processing, and Nanoimprint lithography techniques. First, Distributed Bragg Mirrors in the form of periodic dielectric stacks are fabricated with dense TiO2 layers as the high index material (2.08 in the visible range), and macroporous silica layers as the low index counterpart (1.24 with 50% of porosity). In our approach, a single high temperature annealing step is used to create the porosity in the full stack, highlighting its simplicity and potential for industrial deployment. A defect-free semi-transparent 9-layer stack is obtained and shows a high specular reflectivity up to 96% at normal incidence in its prescribed bandwidth. We also demonstrate the flexibility of our process by making highly reflective DBRs with a tunable reflection range from UV to IR (from 400nm to 1300nm). To demonstrate the versatility of our approach, we optimized a 8-layer DBR and integrated it within in a a-Si:H thin-film solar cell, which resulted in an increase of efficiency by 14.6%. More over, we demonstrated an enhancement of the light emission from an Europium-doped luminescent silica layer that is deposited on a Bragg reflector. Finally we will present our latest results on the possibilities opened by the integration of diffraction gratings fabricated by soft Nanoimprint Lithography, with our DBR structures.

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
Application of In-situ X-ray Absorption, Emission and Powder Diffraction Studies in Nanomaterials Research - From the Design of an In-situ Experiment to Data Analysis