Strong absorption and ultrafast localisation in NaBiS(2) nanocrystals with slow charge-carrier recombination.
Strong absorption and ultrafast localisation in NaBiS(2) nanocrystals with slow charge-carrier recombination.
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DOI：
10.1038/s41467-022-32669-3
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发表时间：
2022-08-24
影响因子：
16.6
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中科院分区：
文献类型：
--
作者：
I-V-VI 2三元硫属化合物作为光伏应用中地球资源丰富、无毒且空气稳定的吸收剂而受到关注。然而，迄今为止探索的半导体具有缓慢上升的吸收起始，并且它们的电荷载流子传输尚未得到很好的理解。在此，我们研究了阳离子无序的NaBiS 2纳米晶体，其具有陡峭的吸收起始，吸收系数达到>105 cm−1，刚好高于其1.4 eV的伪直接带隙。令人惊讶的是，我们还观察到超快（皮秒时间尺度）的光电导衰减和长寿命的电荷载流子人口持续超过一微秒的NaBiS 2纳米晶体。这些不寻常的功能出现，因为本地化的，非键合的S p字符的上价带，这导致了高密度的电子态在带边缘，超快本地化的空间分离的电子和空穴，以及缓慢的衰减被困的空穴。这项工作揭示了在这些系统中的阳离子无序的吸收特性和电荷载流子动力学的关键作用。三元硫属化合物作为无毒、稳定的太阳能吸收剂正受到人们的关注。在这里，作者研究了NaBiS 2，发现阳离子无序是一个关键参数，使其具有高吸收强度和不寻常的电荷载流子动力学。
I-V-VI2 ternary chalcogenides are gaining attention as earth-abundant, nontoxic, and air-stable absorbers for photovoltaic applications. However, the semiconductors explored thus far have slowly-rising absorption onsets, and their charge-carrier transport is not well understood yet. Herein, we investigate cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients reaching >105 cm−1 just above its pseudo-direct bandgap of 1.4 eV. Surprisingly, we also observe an ultrafast (picosecond-time scale) photoconductivity decay and long-lived charge-carrier population persisting for over one microsecond in NaBiS2 nanocrystals. These unusual features arise because of the localised, non-bonding S p character of the upper valence band, which leads to a high density of electronic states at the band edges, ultrafast localisation of spatially-separated electrons and holes, as well as the slow decay of trapped holes. This work reveals the critical role of cation disorder in these systems on both absorption characteristics and charge-carrier kinetics. Ternary chalcogenides are gaining interest as nontoxic, stable solar absorbers. Here, the authors investigate NaBiS2, finding cation disorder to be a critical parameter that enables its high absorption strength and unusual charge-carrier kinetics.
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影响因子：
22
作者：
Jean, Joel;Mahony, Thomas S.;Bulovic, Vladimir
通讯作者：
Bulovic, Vladimir
影响因子：
3.7
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Clarke, Tracey M.;Jamieson, Fiona C.;Durrant, James R.
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Durrant, James R.
影响因子：
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作者：
Gajdos, M;Hummer, K;Bechstedt, F
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Bechstedt, F
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Bernechea, Maria;Miller, Nichole Cates;Konstantatos, Gerasimos
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Konstantatos, Gerasimos
影响因子：
32.5
作者：
Chen, Wei;Dahliah, Diana;Hautier, Geoffroy
通讯作者：
Hautier, Geoffroy