Photoluminescence and Time Resolved Photoluminescence of Organic-inorganic Halide Perovskites

In this work we present PL and time resolved PL (TRPL) measurements of three of these materials: BA2PbI4, BA2MA1Pb2I7, and BA2CuCI4 where BA2 represents (CH3(CH2)3NH3)2, and MA: CH3NH3. Both BA2PbI4 and BA2CuCI4 have a single layer of perovskite material separated by an organic cation layer while BA2MA1Pb2I7 has two atomic layers of perovskite. Our observations indicate the existence of both free and trapped excitons in these systems. Additionally, BA2PbI4 displays two sets of peaks for both trapped and free excitons that evolve with temperature, indicating that as the temperature is reduced the system begins, but does not complete, a phase change from a tetragonal to an orthorhombic crystal lattice. Our result provides new insights on the low temperature behavior of this phase transition, as well as exploring the exciton spectra as a function of both temperature and magnetic field. This material is based upon work supported by the Air Force Office of Scientific Research under awar