Photoconductivity in CdSe quantum dot solids

被引:258
作者
Leatherdale, CA
Kagan, CR
Morgan, NY
Empedocles, SA
Kastner, MA
Bawendi, MG
机构
[1] MIT, Dept Phys, Dept Chem, Cambridge, MA 02139 USA
[2] MIT, Ctr Mat Sci & Engn, Cambridge, MA 02139 USA
关键词
D O I
10.1103/PhysRevB.62.2669
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
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.
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页码:2669 / 2680
页数:12
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