Abstract
Two-dimensional hybrid organic–inorganic perovskites (HOIPs) have emerged as promising materials for light-emitting diode applications. In this study, by using time-of-flight neutron spectroscopy we identified and quantitatively separated the lattice vibrational and molecular rotational dynamics of two perovskites, butylammonium lead iodide (BA)2PbI4 and phenethyl-ammonium lead iodide (PEA)2PbI4. By examining the corresponding temperature dependence, we found that the lattice vibrations, as evidenced by neutron spectra, are consistent with the lattice dynamics obtained from Raman scattering. We revealed that the rotational dynamics of organic molecules in these materials tend to suppress their photoluminescence quantum yield (PLQY) while the vibrational dynamics did not show predominant correlations with the same. Additionally, we observed photoluminescence emission peak splitting for both systems, which becomes prominent above certain critical temperatures where the suppression of PLQY begins. This study suggests that the rotational motions of polarized molecules may lead to a reduction in exciton binding energy or the breaking of degeneracy in exciton binding energy levels, enhancing non-radiative recombination rates, and consequently reducing photoluminescence yield. These findings offer a deeper understanding of fundamental interactions in 2D HOIPs and could guide the design of more efficient light-emitting materials for advanced technological applications.
| Original language | English |
|---|---|
| Article number | 034602 |
| Journal | Journal of the Physical Society of Japan |
| Volume | 94 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 15 2025 |
Funding
The work at University of Virginia (H.S.R., X.H., S.-H.L.) was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under the Award No: DE-SC001644. The neutron scattering experiments at the Material Science and Life Science Experimental facility, Japan Proton Accelerator Research Complex, were performed under the user programs with proposal no: 2017AU0101 and 2018B02028 for 4SEASONS and 2017BU1402 and 2018B0257 for AMATERAS (R.K., Ma.Ko., M.N., D.Z., T.C.). Raman scattering and photoluminescence measurements were performed at the Center for Condensed Matter Sciences, National Taiwan University (W.-L.C, Y.-M.C.). Theory work was partly supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division (M.Y.). Computational work used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725 and resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP0024568. Samples were prepared by A.Z.C. and G.C.J.