Asynchronous Photoexcited Electronic and Structural Relaxation in Lead-Free Perovskites

Vacancy-ordered lead-free perovskites with more-stable crystalline structures have been intensively explored as the alternatives for resolving the toxic and long-term stability issues of lead halide perovskites (LHPs). The dispersive energy bands produced by the closely packed halide octahedral sublattice in these perovskites are meanwhile anticipated to facility the mobility of charge carriers. However, these perovskites suffer from unexpectedly poor charge carrier transport. To tackle this issue, we have employed the ultrafast, elemental-specific X-ray transient absorption (XTA) spectroscopy to directly probe the photoexcited electronic and structural dynamics of a prototypical vacancy-ordered lead-free perovskite (Cs3Bi2Br9). We have discovered that the photogenerated holes quickly self-trapped at Br centers, simultaneously distorting the local lattice structure, likely forming small polarons in the configuration of Vk center (Br2 - dimer). More significantly, we have found a surprisingly long-lived, structural distorted state with a lifetime of ∼59 μs, which is ∼3 orders of magnitude slower than that of the charge carrier recombination. Such long-lived structural distortion may produce a transient "background" under continuous light illumination, influencing the charge carrier transport along the lattice framework. ©

Wang, YingqiCenter for High Pressure Science &Technology Advanced Research (HPSTAR) (författare)
Geng, HuifangELI-HU Non-profit Ltd (författare)
Zhu, TaishanUniversity of Illinois at Urbana-Champaign (författare)
Ertekin, ElifUniversity of Illinois at Urbana-Champaign (författare)
Gosztola, DavidArgonne National Laboratory (författare)
Yang, SizhuoMarquette University (författare)
Huang, JierMarquette University (författare)
Yang, BinDalian Institute of Chemical Physics Chinese Academy of Sciences (författare)
Han, KeliDalian Institute of Chemical Physics Chinese Academy of Sciences (författare)
Canton, Sophie E.ELI-HU Non-profit Ltd,German Electron Synchrotron (DESY)(Swepub:lu)chem-sca (författare)
Kong, QingyuSynchrotron SOLEIL (författare)
Zheng, KaiboLund University,Lunds universitet,NanoLund: Centre for Nanoscience,Annan verksamhet, LTH,Lunds Tekniska Högskola,Kemisk fysik,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Other operations, LTH,Faculty of Engineering, LTH,Chemical Physics,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH,Technical University of Denmark(Swepub:lu)chem-kbz (författare)
Zhang, XiaoyiArgonne National Laboratory (författare)
Argonne National LaboratoryCenter for High Pressure Science &Technology Advanced Research (HPSTAR) (creator_code:org_t)

Ingår i:Journal of the American Chemical Society: American Chemical Society (ACS)141:33, s. 13074-130800002-78631520-5126

Av författaren/redakt...: Liu, Cunming; Wang, Yingqi; Geng, Huifang; Zhu, Taishan; Ertekin, Elif; Gosztola, David; visa fler...; Yang, Sizhuo; Huang, Jier; Yang, Bin; Han, Keli; Canton, Sophie E ...; Kong, Qingyu; Zheng, Kaibo; Zhang, Xiaoyi; visa färre...

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