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Ligand-Free, Quantum-Confined Cs2SnI6 Perovskite Nanocrystals
Chemistry of Materials ( IF 7.2 ) Pub Date : 2017-09-01 00:00:00 , DOI: 10.1021/acs.chemmater.7b02803
Dmitriy S. Dolzhnikov 1, 2 , Chen Wang 1 , Yadong Xu 1 , Mercouri G. Kanatzidis 1, 2 , Emily A. Weiss 1, 2
Affiliation  

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.

中文翻译:

无配体的量子受限Cs 2 SnI 6钙钛矿纳米晶体

卤化钙钛矿型纳米晶体是用于光伏电池的无铅高效活性层的可行前体。我们描述了一种量子合成的Cs 2 SnI 6纳米晶体的新合成程序,该晶体具有在远视到近红外(1.38–1.47 eV)范围内的带隙。热注射合成产生的颗粒没有有机封端配体,随着反应温度的升高,平均直径从12±2.8 nm增加到38±4.1 nm。带隙,第一个激子峰的能量,基态漂白峰(在瞬态吸收光谱中)和光致发光峰与直径的平方成反比,与有效质量为(0.12± 0.02)0,其中m 0是电子的质量,比大块材料中的电子小4.6倍。瞬态吸收测量表明,大约90%的漂白幅度在30 ps内衰减,这可能是由于载流子在未钝化的表面位点上的捕获所致。通过Cs 2 SnI 6纳米晶体溶液的简单滴铸法制得的膜,没有合成后的配体交换或去除,光滑且均匀,抗分层,并且在膜-基底界面上没有可见的缝隙。
更新日期:2017-09-04
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