tailieunhanh - Báo cáo hóa học: " Tailoring photonic metamaterial resonances for thermal radiation"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Tailoring photonic metamaterial resonances for thermal radiation | Bermel et al. Nanoscale Research Letters 2011 6 549 http content 6 1 549 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Tailoring photonic metamaterial resonances for thermal radiation Peter Bermel Michael Ghebrebrhan Michael Harradon Yi Xiang Yeng Ivan Celanovic John D Joannopoulos and Marin Soljacic Abstract Selective solar absorbers generally have limited effectiveness in unconcentrated sunlight because of reradiation losses over a broad range of wavelengths and angles. However metamaterials offer the potential to limit radiation exchange to a proscribed range of angles and wavelengths which has the potential to dramatically boost performance. After globally optimizing one particular class of such designs we find thermal transfer efficiencies of 78 at temperatures over 1 000 C with overall system energy conversion efficiencies of 37 exceeding the Shockley-Quiesser efficiency limit of 31 for photovoltaic conversion under unconcentrated sunlight. This represents a 250 increase in efficiency and 94 decrease in selective emitter area compared to a standard angular-insensitive selective absorber. PACS Keywords metamaterials photonic crystals solar absorbers 1 Background Solar thermophotovoltaic TPV systems offer a distinct approach for converting sunlight into electricity 1-6 . Compared to standard photovoltaics sunlight is not absorbed directly by a photovoltaic material but is instead absorbed by a selective absorber. That selective absorber is thermally coupled to a selective emitter which then thermally radiates electromagnetic radiation. The key challenge to making such a system efficient is achieving a relatively high temperature. Generally this implies high optical concentrations 7 . However one could consider whether there would be another way to concentrate heat in the selective absorber-without using optical concentrators at all. The key idea here is to replace the .