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

The switching behavior of exciton absorption and photoluminescence is systematically explored in hybrid inorganic-organic multiple quantum well structures, based on (C12H25NH3)2PbI4 thin films and single crystals. Two structural phases found between 15 and 75 °C, based on orthorhombic and monoclinic unit cells, show different optical excitons which are demonstrated to arise from the reversible crumpling of the quantum well layers. Structural flips can be controlled by annealing or film thickness, with different thermal hysteresis behavior observed for single crystals and thin films.