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Exciton funneling in light-harvesting organic semiconductor microcrystals for wavelength-tunable lasers

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Science Advances  14 Jun 2019:
Vol. 5, no. 6, eaaw2953
DOI: 10.1126/sciadv.aaw2953
  • Fig. 1 Illustration for exciton funneling in the light-harvesting systems.

    (A) Schematics of light harvesting, where the wide-bandgap hosts (gray spheres) act as antenna and locally formed CT complexes with narrow bandgap (pink spheres) act as acceptor. (B) Diagram for exciton funneling in light-harvesting systems. The black arrows represent the exciton transfer process.

  • Fig. 2 Preparation and structural characterization of C60@OPV light-harvesting microcrystals.

    (A) Chemical structures of OPV and C60, and molecular structure of the resulting CT complex. (B and C) SEM images of typical OPV and C60@OPV microwires. Scale bars, 5 μm (B) and 2 μm (C). (D and E) TEM images of individual OPV and C60@OPV microwires. Scale bars, 2 μm. (F and G) SAED patterns of the corresponding microwires in (D) and (E). Scale bars, 2 1/nm. (H) Raman spectra of individual OPV, C60, and C60@OPV microwires. a.u., arbitrary units. The C60 doping concentration of the C60@OPV microcrystals used for these characterizations is 5.6 mol %.

  • Fig. 3 Exciton funneling into the CT states in the organic light-harvesting microcrystals.

    (A) Absorption spectra of OPV (green), C60@OPV (red) microwires, and C60 dispersed in polymer hosts (black). a.u., arbitrary units. (B) Fluorescence microscopy images of OPV (top) and C60@OPV (bottom) microwires. Scale bars, 20 μm. (C and D) Streak camera images and PL spectra of OPV (C) and C60@OPV (D) microcrystals excited with a 400-nm pulsed laser (~100 fs, 1 kHz). tD and tDA are the average lifetimes of donor (~551 nm) in the absence (pure OPV) and presence (C60@OPV) of the acceptor, respectively. The C60 doping concentration of the C60@OPV microcrystals used for these characterizations is 5.6 mol %.

  • Fig. 4 Theoretical investigation of the CT processes in light-harvesting systems.

    (A) Molecular orbital diagrams of OPV, C60, and CT complex calculated by density function theory. (B) Schematic of efficient exciton funneling for the formation, accumulation, and radiative deactivation of CT excitons in the C60@OPV light-harvesting systems. (C) Maximum emission wavelength of microcrystals versus C60 doping concentration.

  • Fig. 5 Lasing performances in the light-harvesting microwires.

    (A) PL spectra recorded from a typical C60@OPV microwire (doping concentration, 5.6 mol %) pumped with different laser energies. Inset: PL images of the C60@OPV below and above the lasing threshold. Scale bar, 10 μm. (B) Emission intensity (red) and full width at half maximum (FWHM) (black) as a function of pump fluence. (C) Normalized lasing spectra of the OPV microcrystals with different C60 doping concentrations. Inset: Corresponding PL images of the doped OPV microcrystals pumped above lasing thresholds. Scale bars, 10 μm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/6/eaaw2953/DC1

    Section S1. Synthesis procedures of the model compound and light-harvesting microcrystals

    Section S2. Structural characterizations of C60@OPV microcrystals

    Section S3. Luminescence properties of pure OPV, C60, and C60@OPV microwires

    Section S4. Lasing performances of the isolated OPV and C60@OPV microwires

    Fig. S1. The synthetic route of compound OPV.

    Fig. S2. 1H NMR spectra of OPV in CDCl3.

    Fig. S3. Determination of C60 doping concentration in C60@OPV microcrystals.

    Fig. S4. Theoretically predicted growth morphology of OPV crystal.

    Fig. S5. XRD patterns of C60, C60@OPV, pure OPV, and simulated OPV crystals.

    Fig. S6. Confocal microscopy images of C60@OPV microwire.

    Fig. S7. Absolute fluorescence quantum yields of pure OPV and C60@OPV microwires.

    Fig. S8. Optical microscopy images of C60 microwires.

    Fig. S9. Time-resolved photoluminescence (TRPL) decay profiles of C60@OPV microwire.

    Fig. S10. TRPL decay profile of OPV microwire.

    Fig. S11. Fluorescence microscopy images and PL spectra of OPV microcrystals doped with different concentrations of C60.

    Fig. S12. Tunable energy levels upon regulating the degree of CT.

    Fig. S13. Schematic illustration of the homebuilt far-field micro-PL system.

    Fig. S14. TRPL decay profiles of C60@OPV microcrystal at 607 nm below and above the lasing threshold.

    Fig. S15. Simulated electric field intensity distribution in a single C60@OPV microwire.

    Fig. S16. Modulated lasing spectra of C60@OPV microwires (doping concentration, 5.6 mol %) with different lengths.

    Fig. S17. Lasing actions in pure OPV and C60@OPV microwires (doping concentration, 1.7 mol %).

    Fig. S18. Modulated lasing spectra of pure OPV and C60@OPV (doping concentration, 1.7 mol %) microwires with different lengths.

    Fig. S19. Lasing thresholds of C60@OPV microwires with different doping concentrations.

    Fig. S20. Chromaticity coordinates of the doped OPV microcrystal lasers shown in Fig. 5C on the CIE 1931 chromaticity diagram.

    Fig. S21. Device performance of single-crystal field-effect transistors.

    Table S1. Efficiency of energy transfer in C60@OPV microwires.

    References (4250)

  • Supplementary Materials

    This PDF file includes:

    • Section S1. Synthesis procedures of the model compound and light-harvesting microcrystals
    • Section S2. Structural characterizations of C60@OPV microcrystals
    • Section S3. Luminescence properties of pure OPV, C60, and C60@OPV microwires
    • Section S4. Lasing performances of the isolated OPV and C60@OPV microwires
    • Fig. S1. The synthetic route of compound OPV.
    • Fig. S2. 1H NMR spectra of OPV in CDCl3.
    • Fig. S3. Determination of C60 doping concentration in C60@OPV microcrystals.
    • Fig. S4. Theoretically predicted growth morphology of OPV crystal.
    • Fig. S5. XRD patterns of C60, C60@OPV, pure OPV, and simulated OPV crystals.
    • Fig. S6. Confocal microscopy images of C60@OPV microwire.
    • Fig. S7. Absolute fluorescence quantum yields of pure OPV and C60@OPV microwires.
    • Fig. S8. Optical microscopy images of C60 microwires.
    • Fig. S9. Time-resolved photoluminescence (TRPL) decay profiles of C60@OPV microwire.
    • Fig. S10. TRPL decay profile of OPV microwire.
    • Fig. S11. Fluorescence microscopy images and PL spectra of OPV microcrystals doped with different concentrations of C60.
    • Fig. S12. Tunable energy levels upon regulating the degree of CT.
    • Fig. S13. Schematic illustration of the homebuilt far-field micro-PL system.
    • Fig. S14. TRPL decay profiles of C60@OPV microcrystal at 607 nm below and above the lasing threshold.
    • Fig. S15. Simulated electric field intensity distribution in a single C60@OPV microwire.
    • Fig. S16. Modulated lasing spectra of C60@OPV microwires (doping concentration, 5.6 mol %) with different lengths.
    • Fig. S17. Lasing actions in pure OPV and C60@OPV microwires (doping concentration, 1.7 mol %).
    • Fig. S18. Modulated lasing spectra of pure OPV and C60@OPV (doping concentration, 1.7 mol %) microwires with different lengths.
    • Fig. S19. Lasing thresholds of C60@OPV microwires with different doping concentrations.
    • Fig. S20. Chromaticity coordinates of the doped OPV microcrystal lasers shown in Fig. 5C on the CIE 1931 chromaticity diagram.
    • Fig. S21. Device performance of single-crystal field-effect transistors.
    • Table S1. Efficiency of energy transfer in C60@OPV microwires.
    • References (4250)

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