Anomalous photoluminescence enhancement due to hot electron transfer in core–shell Au–CdS nanocrystals
Anomalous photoluminescence enhancement due to hot electron transfer in core–shell Au–CdS nanocrystals
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DOI：
10.1016/j.jlumin.2016.09.011
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发表时间：
2017
影响因子：
3.6
通讯作者：
S. Kahane;V. Sudarsan;S. Mahamuni
中科院分区：
文献类型：
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作者：
S. Kahane;V. Sudarsan;S. Mahamuni
在室温下，增强的光致发光（PL）强度的核-壳Au-CdS纳米晶体（NC）相对于CdS NC的观察，这是在低温下弱影响。作为温度的函数的PL强度描绘了三个不同的区域中的CdS和Au-CdS NC的曲线的性质的差异暗示热电子转移从Au到CdS。尽管Au的费米能级比CdS纳米晶的导电能级低，但等离子体激元诱导的从Au到CdS的电荷转移克服了在室温下增强带边发射强度的势垒。此外，在较低的温度下，PL发射分裂在狭窄和尖锐的明显的特征，从自由激子和束缚激子水平沿着与第一和第二阶声子副本。在核-壳Au-CdS NC的情况下，从自由激子和束缚激子的发射保持不受影响，而声子复制品被扰动;窄线的测量能量值与经验Varshni方程拟合得很好，揭示了CdS的内在本质。目前的工作表明，衰变的等离子体激元产生电子在半导体中，具有巨大潜力的能量收集的概念。
At room temperature, an enhanced photoluminescence (PL) intensity of core–shell Au–CdS nanocrystals (NCs) with respect to that of CdS NCs is observed; that is weakly affected at low temperature. PL intensity as a function of temperature depicts three different regions in CdS and Au–CdS NCs; the difference in the nature of curves implicates hot electron transfer from Au to CdS. Even though, the Fermi level of Au is at lower energy than conduction level of CdS NCs, plasmon induced charge transfer from Au to CdS overcomes the potential barrier that enhances band edge emission intensity at room temperature. Moreover, at lower temperature, PL emission splits in narrow and sharp distinct features from free exciton and bound exciton levels along with the first and second order phonon replica. In case of core–shell Au–CdS NCs, emission from free exciton and bound exciton remains unaffected, while phonon replica are perturbed; measured energy values of narrow lines fit well with the empirical Varshni equation revealing an intrinsic nature of CdS. The present work demonstrates decay of plasmon by generating electron in semiconductor; the concept with great potential for energy harvesting.