Interband and intraband optical studies of PbSe colloidal quantum dots
Interband and intraband optical studies of PbSe colloidal quantum dots
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DOI：
10.1021/jp021187e
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发表时间：
2002-10-17
影响因子：
3.3
通讯作者：
Guyot-Sionnest, P
中科院分区：
文献类型：
--
作者：
Wehrenberg, BL;Wang, CJ;Guyot-Sionnest, P
PbSe纳米胶体表现出明确的激子结构，最低能量激子调谐从0.5到1 eV，作为大小的函数。带边荧光观察到从1.2到2妈妈的小斯托克斯位移，亚微秒的寿命，和近统一的量子产率。在1.064 μ m泵浦时，第一激子衰减与低泵浦强度下的辐射弛豫和较高泵浦强度下的俄歇复合一致。光诱导吸收在大约midgap观察。这些跃迁表现出类似于带间激子的强度，并且是尺寸可调的。它们分别归属于1 S（e，h）-1P（e，h）和1 P（e，h）-1D（e，h）带内激发。1 S（e，h）-1P（e，h）跃迁的带内泵浦-探测测量揭示了短的寿命和声子瓶颈的存在。
PbSe nanocrystal colloids exhibit a well-defined excitonic structure with the lowest energy exciton tuning from 0.5 to 1 eV, as a function of size. Band-edge fluorescence is observed from 1.2 to 2 mum with a small Stokes shift, sub-mus lifetime, and near-unity quantum yield. Upon pumping at 1.064 mum, the first exciton decay is consistent with radiative relaxation at low pump intensity and with Auger recombination at higher pump intensities. Optically induced absorption is observed at approximately midgap. These transitions exhibit strengths similar to the interband exciton and are size-tunable. They are assigned to the 1S(e,h)-1P(e,h) and 1P(e,h)-1D(e,h) intraband excitations. Intraband pump-probe measurements of the 1S(e,h)-1P(e,h) transition reveal a short lifetime and the absence of the phonon bottleneck.