Giant and Tunable Excitonic Optical Anisotropy in Single-Crystal Halide Perovskites

During the last years, giant optical anisotropy has demonstrated its paramount importance for light manipulation. In spite of recent advances in the field, the achievement of continuous tunability of optical anisotropy remains an outstanding challenge. Here, we present a solution to the problem through the chemical alteration of halogen atoms in single-crystal halide perovskites. As a result, we manage to continually modify the optical anisotropy by 0.14. We also discover that the halide perovskite can demonstrate optical anisotropy up to 0.6 in the visible range-the largest value among non-van der Waals materials. Moreover, our results reveal that this anisotropy could be in-plane and out-of-plane depending on perovskite shape-rectangular and square. As a practical demonstration, we have created perovskite anisotropic nano-waveguides and shown a significant impact of anisotropy on high-order guiding modes. These findings pave the way for halide perovskites as a next-generation platform for tunable anisotropic photonics.

Automated summary

In recent years, the significance of giant optical anisotropy in light manipulation has been demonstrated. However, achieving continuous tunability of optical anisotropy has remained a challenge. This study presents a solution to this problem through the chemical alteration of halogen atoms in single-crystal halide perovskites, resulting in the continuous modification of optical anisotropy. Our findings also show that halide perovskites can exhibit high optical anisotropy up to 0.6 in the visible range, the highest value among non-van der Waals materials.