title: Screening in crystalline liquids protects energetic carriers in hybrid perovskites.
abstract: Hybrid lead halide perovskites exhibit carrier properties that resemble those of pristine nonpolar semiconductors despite static and dynamic disorder, but how carriers are protected from efficient scattering with charged defects and optical phonons is unknown. Here, we reveal the carrier protection mechanism by comparing three single-crystal lead bromide perovskites: CH3NH3PbBr3, CH(NH2)2PbBr3, and CsPbBr3We observed hot fluorescence emission from energetic carriers with ~102-picosecond lifetimes in CH3NH3PbBr3or CH(NH2)2PbBr3, but not in CsPbBr3The hot fluorescence is correlated with liquid-like molecular reorientational motions, suggesting that dynamic screening protects energetic carriers via solvation or large polaron formation on time scales competitive with that of ultrafast cooling. Similar protections likely exist for band-edge carriers. The long-lived energetic carriers may enable hot-carrier solar cells with efficiencies exceeding the Shockley-Queisser limit.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Haiming
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Jue
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Prakriti P
authors.initials: PP
authors.lastname: Joshi
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Niesner
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: Kristopher W
authors.initials: KW
authors.lastname: Williams
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Jin
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA. xyzhu@columbia.edu.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Zhu