Planar Black Silicon: disentangling optical and electrical properties of textured interfaces using transformation optics

平面黑硅：使用变换光学解开纹理界面的光学和电学特性

• 批准号: 413644979
• 负责人: Professor Dr. Carsten Rockstuhl
• 金额: --
• 依托单位: Institut für Theoretische Festkörperphysik (TFP)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413644979?language=en
• 关键词: Planar; Black; Silicon; disentangling; optical

Nanotexturing a solar cell’s absorber material leads to a strong and spectrally broadband absorption enhancement of incident sun light. However, nanotexturing the interfaces degrades simultaneously the electronic properties of the optoelectronic device. This denies the complete harvest of the absorption improvement and does not allow to translate it to a comparable improvement in device efficiency. In contrast, external light management structures that leave the absorber material undamaged are optically far from optimum and they provide substantially weaker absorption enhancement.To solve this problem, we propose to capitalize on the notion of transformation optics to design photonic structures that preserve the geometrical flatness of the absorber material, to leave it electrically intact, while acting optically like a textured interface with optimized antireflection and scattering properties. Following transformations optics procedures, the invariance of Maxwell’s equations can be exploited to deduce a material distribution that regulates the light flow in exactly the same way as a template surface texture, e.g. conventional black silicon, would do. By doing so, we are effectively deducing an inhomogeneous planar layer that, when placed on top of the absorber layer, can provide antireflection and light trapping, thus absorption enhancement, equivalent to the template surface texture without its electronic degradation. We will pursue the experimental realization of the dielectric graded refractive index light management structures and demonstrate its integration into a solar cell. As building blocks, we will utilize dielectric high refractive index nanostructures and thin film layers of different materials conformally deposited by an advanced atomic layer deposition technique.Our approach of deducing light management structures with transformation optics, to the best of our knowledge, is pioneering. Our design approach is a departure from currently common transformation optics applications and will open up applications of transformation optics concepts in designing structures for various real devices. Solar energy conversion is the obvious and most important application that would directly benefit from the findings of this project. However, the methods to be developed here may also contribute to the development of novel concepts in other fields of optics. For example, one can also deduce alternative light outcoupling structures in light emitting diodes (LEDs), which is the inverse of what we mainly aim to do here.

太阳能电池吸收材料的纳米纹理可增强入射太阳光的强烈光谱宽带吸收。然而，界面的纳米纹理同时降低了光电器件的电子特性。这否认了吸收改进的完全收获，并且不允许将其转化为设备效率的类似改进。相比之下，使吸收体材料完好无损的外部光管理结构在光学上远非最佳，并且它们提供的吸收增强要弱得多。为了解决这个问题，我们建议利用变换光学的概念来设计光子结构，以保持吸收体材料的几何平坦度，使其电气完好无损，同时在光学上像具有优化的抗反射和散射特性的纹理界面一样。遵循变换光学程序，可以利用麦克斯韦方程组的不变性来推导以与模板表面纹理完全相同的方式调节光流的材料分布，例如传统的黑硅就可以了。通过这样做，我们有效地推导出了一个不均匀的平面层，当将其放置在吸收层顶部时，可以提供抗反射和光捕获，从而增强吸收，相当于没有电子退化的模板表面纹理。我们将追求介电渐变折射率光管理结构的实验实现，并展示其与太阳能电池的集成。作为构建块，我们将利用介电高折射率纳米结构和通过先进原子层沉积技术共形沉积的不同材料的薄膜层。据我们所知，我们用变换光学推导光管理结构的方法是开创性的。我们的设计方法与当前常见的变换光学应用不同，并将开辟变换光学概念在各种实际设备的结构设计中的应用。太阳能转换是显而易见且最重要的应用，将直接受益于该项目的研究结果。 然而，这里开发的方法也可能有助于其他光学领域新概念的发展。例如，人们还可以推导出发光二极管（LED）中的替代光输出耦合结构，这与我们在这里主要目标相反。