Optical properties of organic–inorganic hybrid films prepared by the two-step growth process

Abstract Thin films of microcrystalline (C 8 H 17 NH 3 ) 2 PbBr 4 have been prepared by the two-step growth process as follows: (1) precipitation of nanometer-sized PbBr 2 particles on substrates by vapor deposition and then (2) growth of (C 8 H 17 NH 3 ) 2 PbBr 4 films by exposing PbBr 2 particles to C 8 H 17 NH 3 Br vapor. Atomic force microscope observations reveal that the substrate is fully covered with nanometer-sized rodlike precipitates. X-ray diffraction studies suggest that (C 8 H 17 NH 3 ) 2 PbBr 4 films are found to be microcrystalline form, single phase and highly oriented with the c -axis perpendicular to the substrate surface. (C 8 H 17 NH 3 ) 2 PbBr 4 films show a clear exciton absorption and free-exciton emission even at room temperature. At low temperatures below 40 K, the emission band separates into three bands at 3.07 (A-band), 3.14 (B-band) and 3.20 (C-band) eV, respectively. Both A- and C-bands correspond to the free-exciton emission with large binding energies. On the contrary, time-resolved PL spectra indicate that the B-band is attributed to phosphorescence formed by the intersystem crossing.