Schulz Andreas S, Kozoň Marek, Vancso G Julius, Huskens Jurriaan, Vos Willem L
Complex Photonic Systems (COPS), MESA+ Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Molecular Nanofabrication (MNF), MESA+ Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2024 May 28;128(22):9142-9153. doi: 10.1021/acs.jpcc.4c01541. eCollection 2024 Jun 6.
We present an optical study of the spontaneous emission of lead sulfide (PbS) nanocrystal quantum dots in 3D photonic band gap crystals made from silicon. The nanocrystals emit in the near-infrared range to be compatible with 3D silicon nanophotonics. The nanocrystals are covalently bound to polymer brush layers that are grafted from the Si-air interfaces inside the nanostructure by using surface-initiated atom transfer radical polymerization. The presence and position of the quantum dots were previously characterized by synchrotron X-ray fluorescence tomography. We report both continuous wave emission spectra and time-resolved, time-correlated single photon counting. In time-resolved measurements, we observe that the total emission rate greatly increases when the quantum dots are transferred from suspension to the silicon nanostructures, likely due to quenching (or increased nonradiative decay) that is tentatively attributed to the presence of Cu catalysts during the synthesis. In this regime, continuous wave emission spectra are known to be proportional to the radiative rate and thus to the local density of states. In spectra normalized to those taken on flat silicon outside the crystals, we observe a broad and deep stop band that we attribute to a 3D photonic band gap with a relative bandwidth of up to 26%. The shapes of the relative emission spectra match well with the theoretical density of states spectra calculated with plane-wave expansion. The observed inhibition is 4-30 times, similar to previously reported record inhibitions, yet for coincidental reasons. Our results are relevant to applications in photochemistry, sensing, photovoltaics, and efficient miniature light sources.
我们展示了对硫化铅（PbS）纳米晶体量子点在由硅制成的三维光子带隙晶体中的自发发射的光学研究。这些纳米晶体在近红外范围内发射，以与三维硅纳米光子学兼容。通过表面引发的原子转移自由基聚合，纳米晶体与从纳米结构内部的硅 - 空气界面接枝的聚合物刷层共价结合。量子点的存在和位置先前已通过同步加速器X射线荧光断层扫描进行了表征。我们报告了连续波发射光谱以及时间分辨、时间相关的单光子计数。在时间分辨测量中，我们观察到当量子点从悬浮液转移到硅纳米结构时，总发射率大大增加，这可能是由于猝灭（或增加的非辐射衰减），初步归因于合成过程中铜催化剂的存在。在这种情况下，已知连续波发射光谱与辐射率成正比，因此与局部态密度成正比。在归一化为晶体外部平坦硅上所测光谱的光谱中，我们观察到一个宽而深的禁带，我们将其归因于相对带宽高达26%的三维光子带隙。相对发射光谱的形状与用平面波展开计算的理论态密度光谱匹配良好。观察到的抑制为4至30倍，与先前报道的创纪录抑制相似，但原因不同。我们的结果与光化学、传感、光伏和高效微型光源中的应用相关。
