Enhanced Hot-Carrier Cooling and Ultrafast Spectral Diffusion in Strongly Coupled PbSe Quantum-Dot Solids
Enhanced Hot-Carrier Cooling and Ultrafast Spectral Diffusion in Strongly Coupled PbSe Quantum-Dot Solids
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DOI：
10.1021/nl203235u
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发表时间：
2011-12-01
期刊：
影响因子：
10.8
通讯作者：
Siebbeles, Laurens D. A.
中科院分区：
文献类型：
--
作者：
Gao, Yunan;Talgorn, Elise;Siebbeles, Laurens D. A.
PbSe 量子点固体对于低成本、高效的光电探测器和太阳能电池引起了极大的兴趣。我们使用 1,2-乙二胺作为替代封端配体，采用逐层浸涂法制备了具有高载流子迁移率的 PbSe 量子点固体。在这里，我们提出了关于光生电荷载流子动力学的时间和能量分辨瞬态吸收光谱研究，重点关注光激发后 0-5 ps。我们将观察到的载流子动力学与分散中的量子点的载流子动力学进行了比较，结果表明，量子点固体中的带内载流子冷却速度明显更快。此外，我们发现载流子在几皮秒内从量子点固体中的较高能量位置扩散到较低能量位置。
PbSe quantum-dot solids are of great interest for low cost and efficient photodetectors and solar cells. We have prepared PbSe quantum-dot solids with high charge carrier mobilities using layer-by-layer dip-coating with 1,2-ethanediamine as substitute capping ligands. Here we present a time and energy resolved transient absorption spectroscopy study on the kinetics of photogenerated charge carriers, focusing on 0-5 ps after photoexcitation. We compare the observed carrier kinetics to those for quantum dots in dispersion and show that the intraband carrier cooling is significantly faster in quantum-dot solids. In addition we find that carriers diffuse from higher to lower energy sites in the quantum-dot solid within several picoseconds.