Circular dichroism in non-chiral metal halide perovskites.,Nanoscale

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Circular dichroism in non-chiral metal halide perovskites.
Nanoscale ( IF 5.8 ) Pub Date : 2020-08-17 , DOI: 10.1039/d0nr05232a
Peter C Sercel ₁ , Zeev Valy Vardeny ₂ , Alexander L Efros ₃

Affiliation

We demonstrate theoretically that non-chiral perovskite layers can exhibit circular dichroism (CD) in the absence of a magnetic field and without chiral activation by chiral molecules. The effect is shown to be due to splitting of helical excitonic states which can form in structures of orthorhombic or lower symmetry that exhibit Rashba spin effects. The selective coupling of these helical exciton states to helical light is shown to give rise to circular dichroism. Polarization dependent absorption is shown to occur due to the combined effect of Rashba splitting, in-plane symmetry breaking, and the effect of the exciton momentum on its fine structure, which takes the form of Zeeman splitting in an effective magnetic field. This phenomenon, which can be considered as a manifestation of extrinsic chirality, results in significant CD with an anisotropy factor of up to 30% in orthorhombic perovskite layers under off-normal, top illumination conditions, raising the possibility of its observation in non-chiral perovskite structures.

中文翻译：

非手性金属卤化物钙钛矿中的圆二色性。

我们从理论上证明非手性钙钛矿层可以在没有磁场且没有被手性分子手性活化的情况下表现出圆二色性（CD）。效果表明是由于螺旋分裂可以在正交或更低对称的结构中形成的具有Rashba自旋效应的激子态。这些螺旋激子态与螺旋光的选择性耦合显示出引起圆二色性。由于拉什巴分裂，平面内对称破坏以及激子动量对其精细结构的综合作用，显示出依赖于极化的吸收，激子动量对其有效结构采取塞曼分裂的形式。这种现象可以看作是外在手性的一种表现，导致在非正常，顶部照明条件下，斜方钙钛矿层中的CD各向异性系数高达30％，从而增加了非手性观察的可能性。钙钛矿结构。

更新日期：2020-09-18

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