@article{fc104f94bbcf4e1289638a96a7968943,
title = "Carrier-Specific Femtosecond XUV Transient Absorption of PbI2 Reveals Ultrafast Nonradiative Recombination",
abstract = "Femtosecond carrier recombination in PbI2 is measured using tabletop high-harmonic extreme ultraviolet (XUV) transient absorption spectroscopy and ultrafast electron diffraction. XUV absorption from 45 to 62 eV measures transitions from the iodine 4d core level to the conduction-band density of states. Photoexcitation at 400 nm creates separate and distinct transient absorption signals for holes and electrons, separated in energy by the 2.4 eV band gap of the semiconductor. The shape of the conduction band, and therefore the XUV absorption spectrum, is temperature-dependent, and nonradiative recombination converts the initial electronic excitation into thermal excitation within picoseconds. Ultrafast electron diffraction (UED) is used to measure the lattice temperature and confirm the recombination mechanism. The XUV and UED results support a second-order recombination model with a rate constant of 2.5 × 10-9 cm3/s.",
author = "Lin, {Ming Fu} and Verkamp, {Max A.} and Joshua Leveillee and Ryland, {Elizabeth S.} and Kristin Benke and Kaili Zhang and Clemens Weninger and Xiaozhe Shen and Renkai Li and David Fritz and Uwe Bergmann and Xijie Wang and Andr{\'e} Schleife and Josh Vura-Weis",
note = "Funding Information: This material is based on work supported by the Air Force Office of Scientific Research under AFOSR Award FA9550-14-1-0314 to J.V.-W. Density functional theory results are based on work supported by the National Science Foundation under Grant CBET-1437230. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (Awards OCI-0725070 and ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana−Champaign and its National Center for Supercomputing Applications. The authors thank Prof. Aaron Lindeberg, Dr. Xiaoxi Wu, and Dr. Ehern Mannebach for the discussion of data analysis in electron diffraction and interpretations. AFM, SEM, and XRD measurements were carried out at part in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois. The UED work was performed at SLAC MeV-UED, which is supported in part by the DOE BES Scientific User Facilities Division and SLAC UED/UEM program development fund under Contract DE-AC02-05CH11231. This work was supported as part of the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Award DE-SC00014607. We thank Dr. Matthew Krzyaniak for assistance with global fitting. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",
year = "2017",
month = dec,
day = "21",
doi = "10.1021/acs.jpcc.7b11147",
language = "English (US)",
volume = "121",
pages = "27886--27893",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "50",
}