π-Electronic Co-crystal Microcavities with Selective Vibronic-Mode Light Amplification: Toward Förster Resonance Energy Transfer Lasing

Abstract

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.

Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers

“…Interestingly, excitation dependent PL spectra of 0.5% doped crystal showed a second ASE peak appearing at 2.97 eV for excitation above 200 µJ cm −2 , which may be associated with emission from 0–2 vibronic peak of the host (see Figure S15 in the Supporting Information). This suggests that at high excitation densities, rate of stimulated emission from host states becomes faster than energy transfer to dopant states . On the other hand, PL spectra of 1.5% doped crystals did not show any evidence of the second ASE emission peak even at the highest excitation densities owing to enhanced energy transfer rate.…”

Organic Cocrystals: Beyond Electrical Conductivities and Field‐Effect Transistors (FETs)

“…5years later, Hu and co-workers [60] reported another multi-component WLE materials ( Figure 4, LA',L A 'T' 0.5 % ,L A 'T' 1% ,L A 'T' 3% ,L T ',L U ',L U 'T' 0.5 % , LU'T' 1% ,LU'T' 3% ,and LT'). [76][77][78] Ref. In these supramolecular systems,a ne fficient energy-transfer behavior from pyrene-OFN to pyrene-TCNB occurred due to the well-matched spectra of the precursors and as uitable energy D/A distance.I na ddition to above-mentioned two kinds of acceptors,t here are other acceptors that have been reported for tuning optical properties more recently.…”

“…In these supramolecular systems,a ne fficient energy-transfer behavior from pyrene-OFN to pyrene-TCNB occurred due to the well-matched spectra of the precursors and as uitable energy D/A distance.I na ddition to above-mentioned two kinds of acceptors,t here are other acceptors that have been reported for tuning optical properties more recently. [76][77][78] [74], [1], [26], [4], [21], [43], [ 60], [ 25], [65], [70], [68], [ 72] and [73].…”

Controlling the Output of Organic Micro/Nanolasers

“…The multiwavelength output is crucial for the applications of micro/nanolasers in laser display, multichannel detection, and multiband communication . The simplest way to obtain multiwavelength micro/nanolasers is by introducing multiple kinds of laser dyes into the same one optical microcavity . In particular, the Förster resonance energy transfer material system not only significantly reduces the lasing threshold of donor molecule, but also effectively extends the spectral coverage of organic lasers.…”

“…Compared with their inorganic counterparts, organic materials possess high flexibility and designability at both molecule and assembly levels, readily supporting the manipulation of the laser output. So far, tremendous research effort has been directed toward exploring various strategies for manipulating the output characteristics of organic micro/nanolasers, including wavelength, mode, and spatial directionality . Here we summarize the recent advances of organic micro/nanolasers mainly on the topic of controllable output behaviors.…”