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The effect of quantum size confinement on the optical properties of PbSe nanocrystals as a function of temperature and hydrostatic pressure

机译：量子尺寸限制对PbSe纳米晶体光学性质随温度和静水压力的影响

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摘要

A study based on photoluminescence and absorption measurements as a function of temperature and pressure for PbSe nanocrystals with sizes in the range 3-13 nm reveals the influence of size quantum confinement on the observed variation. In the case of the temperature variation, the effective bandgap changes from showing a positive rate of change to showing a negative one (for a quantum dot 3 nm in diameter), which can be accounted for by incorporating a linear variation of the carrier effective masses into a simple calculation of the exciton ground state in the quantum dot. In the case of the pressure variation, we observe a clear inverse correlation between the absolute value of the pressure coefficient and the nanocrystal size, a signature of quantum size confinement, with values changing from -76 to -41 meV GPa-1 for quantum dots ranging from 13 to 3 nm in diameter, respectively, clearly smaller in absolute value than the rate for bulk PbSe (-84 meV GPa~(-1)). We used again the hypothesis of a linear variation of the carrier effective masses with pressure in order to fit this experimental variation quantitatively.
机译：对于尺寸在3-13 nm范围内的PbSe纳米晶体，基于光致发光和吸收测量值随温度和压力的变化进行的研究揭示了尺寸量子限制对观测到的变化的影响。在温度变化的情况下，有效带隙从显示正的变化率变为显示负的变化率（对于直径为3 nm的量子点），这可以通过考虑载体有效质量的线性变化来解决。简单地计算出量子点中激子的基态。在压力变化的情况下，我们观察到压力系数的绝对值与纳米晶体尺寸之间存在明显的反相关关系，这是量子尺寸限制的标志，量子点的值从-76变为-41 meV GPa-1直径分别为13到3 nm，绝对值明显小于块状PbSe的比率（-84 meV GPa〜（-1））。为了定量地拟合该实验变化，我们再次使用了载流子有效质量随压力线性变化的假设。

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