Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Center for Nanophotonics, FOM Institute AMOLF , 1098 XG Amsterdam, The Netherlands.
Nano Lett. 2016 Oct 12;16(10):6467-6471. doi: 10.1021/acs.nanolett.6b02971. Epub 2016 Sep 12.
Approaching the theoretically limiting open circuit voltage (V) of solar cells is crucial to optimize their photovoltaic performance. Here, we demonstrate experimentally that nanostructured layers can achieve a fundamentally larger Fermi level splitting, and thus a larger V, than planar layers. By etching tapered nanowires from planar indium phosphide (InP), we directly compare planar and nanophotonic geometries with the exact same material quality. We show that the external radiative efficiency of the nanostructured layer at 1 sun is increased by a factor 14 compared to the planar layer, leading to a 70 mV enhancement in V. The higher voltage arises from both the enhanced outcoupling of photons, which promotes radiative recombination, and the lower active material volume, which reduces bulk recombination. These effects are generic and promise to enhance the efficiency of current record planar solar cells made from other materials as well.
接近太阳能电池的理论极限开路电压（V）对于优化其光伏性能至关重要。在这里，我们通过实验证明，纳米结构层可以实现比平面层更大的费米能级分裂，从而实现更大的 V。通过从平面磷化铟（InP）中刻蚀锥形纳米线，我们直接比较了具有相同材料质量的平面和纳米光子学几何形状。我们表明，与平面层相比，纳米结构层在 1 个太阳时的外部辐射效率提高了 14 倍，导致 V 提高了 70 mV。更高的电压来自于光子的增强外耦合，这促进了辐射复合，以及活性材料体积的降低，这减少了体复合。这些效应是通用的，并有望提高由其他材料制成的当前平面太阳能电池的效率。
