Exciton switching and Peierls transitions in hybrid inorganic-organic self-assembled quantum wells

Hybrid organic-inorganic perovskite semiconductors provide significant opportunities as multifunctional materials for many electronic and optoelectronic applications. These include organic-inorganic light emitting diodes, organicinorganic field-effect transistors, and nonlinear optical switches based on strong exciton-photon coupling in microcavity photonic architectures. 1‐4 The basic structure of these lead II halide-based two-dimensional 2D pervoskites takes the general form R-NH32PbI4 where R is organic consisting of layers of corner-sharing lead iodide octahedra with bilayers of organic cations stacked between the inorganic layers. 5‐7 These form ‘natural’ multiple quantum well structures, where wells of the 2D inorganic semiconducting layer are clad by barriers of the wider bandgap organic layers. Typical layer thicknesses of well and barrier are 6 and 10 A, respectively. The low dimensionality of carriers confined within the inorganic layers by quantum confinement combined with the large dielectric mismatch giving dielectric confinement between the layers, enables formation of stable excitons with large binding energy even at room temperatures. 8,9 These hybrids are thermally stable up