New links found between structure of Ruddlesden-Popper perovskites and optoelectronic properties

Following advances in solution-processed photovoltaics, metal halide perovskites have found use in various devices, ranging from light emitting diodes (LEDs) to field-effect transistors, X-ray scintillators and metamaterials. One such type of crystal, called Ruddlesden-Popper perovskites, has drawn attention as highly efficient material for LEDs. Work from Cortecchia et al. shines new light on how their exceptionally deformable crystal structure influences the optoelectronic characteristics.

The authors report characterizations of the thermal-induced structural transformations of the butylammonium-based Ruddlesden-Popper lead iodide series. With the help of density functional theory calculations, the group found how changes in crystal packing and lattice contraction induced by phase transitions affect the material’s absorption and photoluminescence.

The findings provide the first insight of how changes in octahedral tilt affect the band-gap evolution in a double layer perovskite and serve as fundamental guidelines to synthetically engineer perovskite crystals. Ruddlesdsen-Popper perovskites have been noted for their ability to endure deformations in octahedral coordination and tilt, which allows their structure to be dynamically tuned to achieve desired characteristics by exploiting phase transitions. These occur at temperatures up to 7°C in such materials, potentially pointing to their future use in all-optical switching photonic devices.

The group identified the out-of-plane tilt of lead iodide octahedra as the main parameter affecting the excitonic absorption and luminescence energy. Photoluminescence properties were highly sensitive to structural conformations.

The authors said the work showcases the relevance of structure-optical properties relationship, which might one day be exploited to dynamically tune layered perovskites’ optoelectronic characteristics via external stimuli. The group hopes their work will lead to systems with controlled luminescence and improved efficiency and further look to better understand the structural effects on emission bandwidth.

Source: “Structure-controlled optical thermoresponse in Ruddlesden-Popper layered perovskites,” by D. Cortecchia, S. Neutzner, J. Yin, T. Salim, A. R. Srimath Kandada, A. Bruno, Y. M. Lam, J. Martí-Rujas, A. Petrozza, and C. Soci, APL Materials (2018). The article can be accessed at https://doi.org/10.1063/1.5045782 .