ISIS & icFRC , Université de Strasbourg and CNRS , 8 allée Gaspard Monge , Strasbourg 67000 , France.
Department of Chemistry , The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033 , Japan.
Nano Lett. 2018 Jul 11;18(7):4396-4402. doi: 10.1021/acs.nanolett.8b01442. Epub 2018 Jun 19.
π-conjugated organic microcrystals often act as optical resonators in which the generated photons in the crystal are confined by the reflection at the crystalline facets and interfere to gain lasing action. Here, we fabricate microcrystals from a mixture of carbon-bridged oligo- para-phenylenevinylenes (COPVs) with energy-donor (D) and energy-acceptor (A) characters. Upon weak excitation of the single D-A co-crystal, Förster resonance energy transfer (FRET) takes place, exhibiting spontaneous emission from A. In contrast, upon strong pumping, stimulated emission occurs before FRET, generating lasing action from D. Lasing occurs with single- and dual-vibronic levels, and the lasing wavelength can be modulated by the doping amount of A. Time-resolved spectroscopic studies reveal that the rate constant of lasing is more than 20 times greater than that of FRET. Furthermore, microcrystals, vertically grown on a Ag-coated substrate, reduce the lasing threshold by one-fourth. This study proposes possible directions toward organic solid FRET lasers with microcrystalline resonators.
π 共轭有机微晶体通常作为光学谐振器，其中晶体中产生的光子被晶体表面的反射限制并干涉以获得激光作用。在这里，我们从具有供体 (D) 和受体 (A) 性质的碳桥联聚对苯乙炔 (COPV) 混合物中制造微晶体。在单 D-A 共晶体的弱激发下，发生Förster 共振能量转移 (FRET)，从 A 中自发发射。相比之下，在强泵浦下，在 FRET 之前发生受激辐射，从 D 中产生激光作用。激光作用发生在单和双振动态上，并且激光波长可以通过 A 的掺杂量来调制。时间分辨光谱研究表明，激光的速率常数大于 FRET 的速率常数 20 倍以上。此外，垂直生长在 Ag 涂层基底上的微晶体将激光阈值降低了四分之一。这项研究为具有微晶体谐振器的有机固态 FRET 激光器提出了可能的方向。
