Rational Design of Two-Dimensional Halide Perovskites for Stabilizing FAPbI₃ and CsPbI₃ Pure Phases

Two-dimensional (2D) halide perovskites are a sub-class of 3D perovskites, which have emerged as a new class of solution-processed organic-inorganic (hybrid) low-dimensional semiconductors. They imbibe their properties from four exciting classes of novel materials - quantum wells, atomically thin 2D materials, organic semiconductors, and 3D halide perovskites. There is growing consensus that their physical properties are dictated by the interaction between the organic cation and the inorganic framework, which presents a unique opportunity to tailor their behaviours. Moreover, the 2D perovskites have demonstrated technologically relevant durability in contrast to the 3D perovskites and their synergistic integration with 3D perovskites has demonstrated the path for overcoming the issue of long-term durability in halide perovskite-based optoelectronic devices.
In this talk I will describe our recent work on the rational desigh of 2D perovskites on stabilizing the undesired delta or yellow phases to perovskite or black phase, specifically in the narrow bandgap Formamidinium Lead Iodide and wide bandgap Cesium Lead Iodide. These stabilized phases demonstrate commercially relevant stability under temperature (85 C) and light illumination. Finally, if time permits, I will also present a new approach for the fabrication of solution-processed stacks of perovskites, which opens the possibility of building any desired multilayered heterostructure-based perovskite optoelectronic device.

Key references
Metcalf et al Two-dimensional perovskite templates for durable and efficient formamidinium solar cells Science (in final revision).
Sidhik et al Deterministic fabrication of 3D/2D perovskite bilayer stacks for durable and efficient solar cells Science 2022 Vol 377, Issue 6613 pp. 1425-1430
Li W et al Light-activated interlayer contraction in two-dimensional perovskites for high-efficiency solar cells. Nat Nanotechnol. 2022 Jan;l 7(1):45-52.
Sidhik et al Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High-Efficiency Devices. Adv Mater. 2021 Jul;33(29):e2007176.
Blancon JC et al, Semiconductor physics of organic-inorganic 2D halide perovskites.
Nature Nanotechnol. 2020 Dec; 15(12):969-985.