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Formation of long-lived color centers for broadband visible light emission in low-dimensional layered perovskites

DOI: 10.1021/jacs.7b10223 DOI Help

Authors: Edward P. Booker (University of Cambridge) , Tudor H. Thomas (University of Cambridge) , Claudio Quarti (University of Mons) , Michael R. Stanton (University of Cambridge) , Cameron D. Dashwood (University of Cambridge) , Alexander J. Gillett (University of Cambridge) , Johannes M. Richter (University of Cambridge) , Andrew J. Pearson (University of Cambridge) , Nathaniel J. L. K. Davis (University of Cambridge) , Henning Sirringhaus (University of Cambridge) , Michael B. Price (University of Cambridge) , Neil C. Greenham (University of Cambridge) , David Beljonne (University of Mons) , Sian E. Dutton (University of Cambridge) , Felix Deschler (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: November 2017
Diamond Proposal Number(s): 14886

Abstract: We investigate the origin of the broadband visible emission in layered hybrid lead-halide perovskites and its connection with structural and photophysical properties. We study <001> oriented thin films of hexylammonium (HA) lead iodide, (C6H16N)2PbI4, and dodecylammonium (DA) lead iodide, (C12H28N)2PbI4 by combining first-principles simulations with time-resolved photoluminescence, steady-state absorption and X-ray diffraction measurements on cooling from 300 K to 4 K. Ultrafast transient absorption and photoluminescence measurements are used to track the formation and recombination of emissive states. In addition to the excitonic photoluminescence near the absorption edge, we find a red-shifted, broadband (full-width at half maximum of about 0.4 eV), emission band below 200 K, similar to emission from <110> oriented bromide 2D perovskites at room temperature. The lifetime of this sub-bandgap emission exceeds that of the excitonic transition by orders of magnitude. We use X-ray diffraction measurements to study the changes in crystal lattice with temperature. We report changes in the octahedral tilt and lattice spacing in both materials, together with a phase change around 200 K in DA2PbI4. DFT simulations of the HA2PbI4 crystal structure indicate that the low-energy emission is due to interstitial iodide and related Frenkel defects. Our results demonstrate that white-light emission is not limited to <110> oriented bromide 2D perovskites but a general property of this class of system and highlight the importance of defect control for the formation of low-energy emissive sites, which can provide a pathway to design tailored white-light emitters.

Subject Areas: Chemistry, Materials


Instruments: I07-Surface & interface diffraction