Photoconductivity in CdSe quantum dot solids
Photoconductivity in CdSe quantum dot solids
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DOI：
10.1103/physrevb.62.2669
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发表时间：
2000-07-15
影响因子：
3.7
通讯作者：
Bawendi, MG
中科院分区：
文献类型：
--
作者：
Leatherdale, CA;Kagan, CR;Bawendi, MG
我们报道了三维紧密堆积的胶体CdSe量子点的光电导和电场诱导光致发光猝灭的测量结果。我们的测量表明，光激发的量子受限激子被外加电场电离，其速率取决于量子点的大小和表面钝化。限制在量子点核心的电子-空穴对的分离比捕获在表面的载流子的分离需要更多的能量，并通过隧道过程发生。对于初始电荷分离步骤，我们提出了一个简单的共振隧穿模型，该模型定性地再现了光电导随外加电场的大小和表面的依赖关系。我们发现，随着非辐射和辐射复合路径与电荷分离的竞争日益加剧，电荷产生效率随着温度的升高而增加。
We report measurements of photoconductivity and electric field induced photoluminescence quenching in three-dimensional close-packed solids of colloidal CdSe quantum dots. Our measurements suggest that photoexcited, quantum confined excitons are ionized by the applied electric field with a rate that depends on both the size and surface passivation of the quantum dots. Separation of electron-hole pairs confined to the core of the quantum dot requires significantly more energy than separation of carriers trapped at the surface and occurs through tunneling processes. We present a simple resonant tunneling model for the initial charge separation step that qualitatively reproduces both the size and surface dependence of the photoconductivity as a function of applied field. We show that the charge generation efficiency increases with increasing temperature as nonradiative and radiative recombination pathways increasingly compete with charge separation.