Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Nano Lett. 2010 Aug 11;10(8):3135-41. doi: 10.1021/nl101929j.
For ultrathin films of a given material, light absorption is proportional to the film thickness. However, if the optical constants of the film are chosen in an optimal way, light absorption can be high even for extremely thin films and optical path length. We derive the optimal conditions and show how the maximized absorptance depends on film thickness. It is then shown that the optimal situation can be emulated by tuning of the geometric parameters in feasible nanocomposites combining plasmonic materials with semiconductors. Useful design criteria and estimates for the spatial absorption-distribution over the composite materials are provided. On the basis of efficient exchange of oscillator strength between the plasmonic and semiconductor constituents, a high quantum yield for semiconductor absorption can be achieved. The results are far-reaching with particularly promising opportunities for plasmonic solar cells.
对于给定材料的超薄薄膜，光吸收与薄膜厚度成正比。然而，如果以最佳方式选择薄膜的光学常数，即使对于极薄的薄膜和光程长度，光吸收也可以很高。我们推导出最佳条件，并展示了最大吸收率如何取决于薄膜厚度。然后表明，可以通过调整等离子体材料与半导体相结合的可行纳米复合材料的几何参数来模拟最佳情况。提供了复合材料的空间吸收分布的有用设计标准和估计。基于等离子体和半导体成分之间的振子强度的有效交换，可以实现半导体吸收的高光量子产率。这些结果意义深远，对于等离子体太阳能电池来说，尤其具有广阔的前景。
