Ultrafast photoluminescence from (C6H5C2H4NH3)2PbI4

We report on ultrafast radiative exciton lifetime of (C6H5C2H4NH3)(2) PbI4 (PhE-PbI4 for short) film, which is one of the inorganic-organic PbI-based layered perovskite semiconductors with large exciton-oscillator strength. The radiative lifetime of excitons in 20-nm-thick polycrystalline film was found to be very short, similar to 10 ps through time-resolved photoluminescence (PL) measurements. In addition, we propose a new scheme for ultrafast PL in order to circumvent the loss of coherent volume of an exciton center-of-mass wave function due to the exciton scattering: a periodic structure of thin PhE-PbI4 rods in a slab waveguide. Under the strong coupling between an exciton and a Bragg mode, we expect that the macroscopic coherence will be maintained even at room temperature along with the ultrafast PL with lifetime of a few ps or less. (C) 2000 Elsevier Science B.V. All rights reserved.