TY - JOUR
T1 - Ligand-Free, Quantum-Confined Cs2SnI6 Perovskite Nanocrystals
AU - Dolzhnikov, Dmitriy S.
AU - Wang, Chen
AU - Xu, Yadong
AU - Kanatzidis, Mercouri G.
AU - Weiss, Emily A.
N1 - Funding Information:
Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. We thank Jack Olding for helping with photoluminescence measurements.
Funding Information:
This work was supported as part of the Argonne-Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DESC0001059. This work made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology
PY - 2017/9/26
Y1 - 2017/9/26
N2 - Tin-halide perovskite nanocrystals are a viable precursor for lead-free, high-efficiency active layers for photovoltaic cells. We describe a new synthetic procedure for quantum-confined Cs2SnI6 nanocrystals with size-dependent band gaps in the long-visible to near-infrared (1.38-1.47 eV). Hot injection synthesis produces particles with no organic capping ligands, with average diameters that increase from 12 ± 2.8 nm to 38 ± 4.1 nm with increasing reaction temperature. The band gap, energies of the first excitonic peak, ground-state bleach peak (in the transient absorption spectrum), and photoluminescence peak depend linearly on the inverse square of diameter, consistent with quantum-confined excitons with an effective mass of (0.12 ± 0.02)m0, where m0 is the mass of an electron, a factor of 4.6 smaller than that in the bulk material. Transient absorption measurements show that approximately 90% of the bleach amplitude decays within 30 ps, probably because of carrier trapping on unpassivated surface sites. The films made by simple drop-casting of Cs2SnI6 nanocrystal solutions, with no postsynthetic ligand exchange or removal, are smooth and uniform, resist delamination, and have no visible gaps at the film-substrate interface.
AB - Tin-halide perovskite nanocrystals are a viable precursor for lead-free, high-efficiency active layers for photovoltaic cells. We describe a new synthetic procedure for quantum-confined Cs2SnI6 nanocrystals with size-dependent band gaps in the long-visible to near-infrared (1.38-1.47 eV). Hot injection synthesis produces particles with no organic capping ligands, with average diameters that increase from 12 ± 2.8 nm to 38 ± 4.1 nm with increasing reaction temperature. The band gap, energies of the first excitonic peak, ground-state bleach peak (in the transient absorption spectrum), and photoluminescence peak depend linearly on the inverse square of diameter, consistent with quantum-confined excitons with an effective mass of (0.12 ± 0.02)m0, where m0 is the mass of an electron, a factor of 4.6 smaller than that in the bulk material. Transient absorption measurements show that approximately 90% of the bleach amplitude decays within 30 ps, probably because of carrier trapping on unpassivated surface sites. The films made by simple drop-casting of Cs2SnI6 nanocrystal solutions, with no postsynthetic ligand exchange or removal, are smooth and uniform, resist delamination, and have no visible gaps at the film-substrate interface.
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U2 - 10.1021/acs.chemmater.7b02803
DO - 10.1021/acs.chemmater.7b02803
M3 - Article
AN - SCOPUS:85029934999
VL - 29
SP - 7901
EP - 7907
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 18
ER -