Diroll Benjamin T
Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States.
Nano Lett. 2020 Nov 11;20(11):7889-7895. doi: 10.1021/acs.nanolett.0c02409. Epub 2020 Oct 29.
Colloidal quantum wells, or nanoplatelets, exhibit large, circularly polarized optical Stark effects under sub-band-gap femtosecond illumination. The optical Stark effect is measured for CdSe colloidal quantum wells of several thicknesses and separately as a measure of pump photon energy, pump fluence, and temperature. These measurements show that optical Stark effects in colloidal quantum wells shift the absorption features up to 5 meV, at the intensities up to 2.9 GW·cm and large detuning (>400 meV) of the pump photon energy from the band edge absorption. Optical Stark shifts are underpinned by large transition dipoles of the colloidal quantum wells (μ = 15-23 D), which are larger than those of any reported colloidal quantum dots or epitaxial quantum wells. The rapid (<500 fs), narrow band blue shift of the excitonic features under circular excitation indicates the viability of these materials beyond light emission such as spintronics or all-optical switching.
胶体量子阱，即纳米片，在亚带隙飞秒光照下表现出强烈的圆偏振光学斯塔克效应。对几种不同厚度的CdSe胶体量子阱分别测量了光学斯塔克效应，以研究泵浦光子能量、泵浦通量和温度的影响。这些测量结果表明，在强度高达2.9 GW·cm²且泵浦光子能量与带边吸收存在较大失谐（>400 meV）的情况下，胶体量子阱中的光学斯塔克效应可使吸收特征峰移动高达5 meV。光学斯塔克位移由胶体量子阱的大跃迁偶极矩（μ = 15 - 23 D）支撑，该偶极矩大于任何已报道的胶体量子点或外延量子阱。圆偏振激发下激子特征的快速（<500 fs）、窄带蓝移表明这些材料在自旋电子学或全光开关等光发射之外的应用具有可行性。
