论文标题
量子点固体中光学增益的定量电化学控制
Quantitative electrochemical control over optical gain in quantum-dot solids
论文作者
论文摘要
实现解决方案处理的量子点（QD）激光器是纳米科学的圣地之一。 QD激光器尚未商业化的原因是，激光阈值太高了：每个QD需要> 1个激子，这是由于快速的非辐射螺旋钻重组而难以实现的。可以通过QD的电子掺杂来降低光学增益阈值，从而降低带边缘附近的吸收，从而使刺激的发射（SE）很容易胜过吸收。在这里，我们表明，通过CDSE/CDS/ZNS QD的电化学掺杂膜，我们可以实现对增益阈值的定量控制。我们获得稳定且可逆的掺杂，每个QD多达两个电子。我们使用超快的光谱电化学来量化增益阈值和电荷载体动力学，并在实验和理论之间实现定量一致。在具有明显增益系数的一系列波长的范围内，增益阈值每QD达到〜10^-5激子的记录低值。这些结果表明，对掺杂的QD固体中增益阈值的前所未有的控制水平，为创建廉价，可加工的低阈值QD-Lasers铺平了道路。
Realizing solution processed quantum dot (QD) lasers is one of the holy-grails of nanoscience. The reason that QD lasers are not yet commercialized is that the lasing threshold is too high: one needs > 1 exciton per QD, which is hard to achieve due to fast non-radiative Auger recombination. The optical gain threshold can be reduced by electronic doping of the QDs, which lowers the absorption near the band-edge, such that the stimulated emission (SE) can easily outcompete absorption. Here, we show that by electrochemically doping films of CdSe/CdS/ZnS QDs we achieve quantitative control over the gain threshold. We obtain stable and reversible doping with up to two electrons per QD. We quantify the gain threshold and the charge carrier dynamics using ultrafast spectroelectrochemistry and achieve quantitative agreement between experiments and theory. Over a range of wavelengths with appreciable gain coefficients, the gain thresholds reach record-low values of ~10^-5 excitons per QD. These results demonstrate an unprecedented level of control over the gain threshold in doped QD solids, paving the way for the creation of cheap, solution-processable low-threshold QD-lasers.
