| Autor: |
Savill KJ; Department of Physics , University of Oxford , Clarendon Laboratory, Parks Road , Oxford OX1 3PU , U.K., Klug MT; Department of Physics , University of Oxford , Clarendon Laboratory, Parks Road , Oxford OX1 3PU , U.K., Milot RL; Department of Physics , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , U.K., Snaith HJ; Department of Physics , University of Oxford , Clarendon Laboratory, Parks Road , Oxford OX1 3PU , U.K., Herz LM; Department of Physics , University of Oxford , Clarendon Laboratory, Parks Road , Oxford OX1 3PU , U.K. |
| Abstrakt: |
Reports of slow charge-carrier cooling in hybrid metal halide perovskites have prompted hopes of achieving higher photovoltaic cell voltages through hot-carrier extraction. However, observations of long-lived hot charge carriers even at low photoexcitation densities and an orders-of-magnitude spread in reported cooling times have been challenging to explain. Here we present ultrafast time-resolved photoluminescence measurements on formamidinum tin triiodide, showing fast initial cooling over tens of picoseconds and demonstrating that a perceived secondary regime of slower cooling instead derives from electronic relaxation, state-filling, and recombination in the presence of energetic disorder. We identify limitations of some widely used approaches to determine charge-carrier temperature and make use of an improved model which accounts for the full photoluminescence line shape. Further, we do not find any persistent polarization anisotropy in FASnI 3 within 270 fs after excitation, indicating that excited carriers rapidly lose both polarization memory and excess energy through interactions with the perovskite lattice. |
