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导致入射太阳光的强光谱宽带吸收增强。然而，界面的纳米纹理同时降低了光电器件的电子性能。这否定了吸收改善的完全收获，并且不允许将其转化为设备效率的可比改进。相比之下，使吸收材料不受损坏的外部光管理结构在光学上远未达到最佳效果，并且它们提供的吸收增强效果明显较弱。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，以保持吸收材料的几何平面，使其在电上保持完整，同时在光学上像一个具有优化抗反射和散射特性的纹理界面。根据变换光学过程，可以利用麦克斯韦方程的不变性来推导出一种材料分布，这种材料分布调节光流的方式与模板表面纹理（例如传统的黑硅）完全相同。通过这样做，我们有效地推导出一种非均匀平面层，当将其放置在吸收层的顶部时，可以提供抗反射和光捕获，从而增强吸收，相当于模板表面纹理而不会产生电子退化。我们将继续进行电介质渐变折射率光管理结构的实验实现，并演示其与太阳能电池的集成。我们将利用电介质高折射率纳米结构和不同材料的薄膜层，通过先进的原子层沉积技术共形沉积。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。我们的设计方法与目前常见的变换光学应用不同，并将在各种实际设备的结构设计中开辟变换光学概念的应用。太阳能转换是最明显和最重要的应用，将直接受益于这个项目的发现。然而，这里发展的方法也可能有助于在光学的其他领域的新概念的发展。例如，人们还可以推断出发光二极管（led）中的其他光解耦结构，这与我们在这里主要要做的相反。