论文标题
CDSE纳米片的激子自旋固定寿命随核/壳形态显着增加
Excitonic Spin-Coherence Lifetimes in CdSe Nanoplatelets Increase Significantly with Core/Shell Morphology
论文作者
论文摘要
我们报告了胶体CDSE纳米平板电脑的自旋偏振瞬态吸收，这是厚度（2至6个单层厚度）和核/外壳基序的功能。使用共旋转泵合并组合的电流调制，我们敏感地观察了自旋偏置过渡。仅核心纳米板片显示出很少的旋转寿命，随着层厚度而弱增加。差异的自旋偏振信号的光谱含量表明Biexciton结合能随着厚度的增加而降低，并且值比以前报道的较小。具有控制厚度的CD的壳生长，将电子从孔中部分迁移，在室温下将自旋寿命显着增加到〜49 picseconds。 ZnS壳的实施不会改变离界化，但会改变表面终止，将自旋寿命提高到〜100 ps，并加强了这样的解释，即表面终止严重影响旋转相干性，这可能是由于悬空悬空键。磁场中的自旋进液都证实了室温下的长相干寿命，并且产生了激子的G因子。
We report spin-polarized transient absorption for colloidal CdSe nanoplatelets as functions of thickness (2 to 6 monolayer thickness) and core/shell motif. Using electro-optical modulation of co- and cross-polarization pump-probe combinations, we sensitively observe spin-polarized transitions. Core-only nanoplatelets exhibit few-picosecond spin lifetimes that weakly increase with layer thickness. Spectral content of differenced spin-polarized signals indicate biexciton binding energies that decrease with increasing thickness and smaller values than previously reported. Shell growth of CdS with controlled thicknesses, which partially delocalize the electron from the hole, significantly increases the spin lifetime to ~49 picoseconds at room temperature. Implementation of ZnS shells, which do not alter delocalization but do alter surface termination, increased spin lifetimes up to ~100 ps, bolstering the interpretation that surface termination heavily influences spin coherence, likely due to passivation of dangling bonds. Spin precession in magnetic fields both confirms long coherence lifetime at room temperature and yields excitonic g-factor.
