期刊
CHEMISTRY OF MATERIALS
卷 29, 期 18, 页码 7901-7907出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.7b02803
关键词
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资金
- Argonne-Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0001059]
- Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource [NSF ECCS-1542205]
- MRSEC at the Materials Research Center [NSF DMR-1121262]
- International Institute for Nanotechnology (IIN)
- Keck Foundation
- State of Illinois, through IIN
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)m(0), where m(0) 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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