Interplay between structure and physical properties in organic-inorganic 2D perovskites

Recent studies have hinted at the importance of dynamic interactions between electronic states and the lattice in organic-inorganic 2D perovskites (2DPs). It is thus critical to understand the interplay between structure and properties during light excitation and in operating devices. Here, we investigate these effects by exploring the 2DPs phase space in terms of both layer thickness and interlayer organic spacer rigidity. We reveal the relation between structural and photophysical properties in 2DPs by correlating structural and optoelectronic spectroscopy at the sub-micron scale and under magnetic field, with support from theory. Our work demonstrates that during photoexcitation strongly bound excitons are generated and their characteristics (mass, size, energy) can be modulated not only by the thickness of the 2D perovskites layers as in classic quantum-wells but also through structural distortions such as perovskite octahedra tilting induced by the organic spacer or crystal edge termination.[1] Similar effects are linked to local compositional changes or artificial interfaces, resulting in giant enhancement of photoemission at the 2DP and WS₂ interface.[2]
[1] Blancon et al., Science 355, 1288 (2017) & Nat. Commun. 9, 2254 (2018)
[2] Yang et al., Nano Lett. 19, 4852 (2019).