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Highly Emissive Hierarchical Uniform Dialkylfluorene-Based Dimer Microcrystal for Ultraviolet Organic Laser
摘要： Hierarchically uniform condensed structure of light-emitting conjugated molecules is an effective platform to obtain excellent electronic landscape with little physical defect and further improve photophysical property. Herein, highly emissive dialkylfluorene-based dimer crystal structure is constructed with crystalline-enhanced emission for ultraviolet organic microlasers. Instable planar conformation of fluorene dimer can be stabilized in a rigid crystalline framework, which is a fundamental factor to fabricate hierarchically uniform structure (including planar conformational molecules and periodical molecular packing in crystalline structure). Therefore, high photoluminescence quantum efficiency (PLQE) of 50% and 75% are obtained for neat spin-coated film and single crystals, attributing to the little physical defect in this hierarchical oriented structure. This robust crystalline-enhanced emission enables its microcrystals to construct ultraviolet organic lasers (395 nm) with a low threshold of 7.65×10-3 nJ cm-2 pulse-1, which is 4 times lower than that of controlled trimer one (TDMeF). These observations reasonably confirm that hierarchically ordered architecture of conjugated materials show great promise in optoelectronic applications.
关键词： Plasmonics,Dimer Microcrystal,Dialkylfluorene,Hybrid Materials,Magnetic,Optical,Ultraviolet Organic Laser
更新于2025-09-23 15:19:57
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Deepa??Blue Thiophenea??Based Steric Oligomers as a Lowa??Threshold Laser Gain and Host Material
摘要： Thiophene-based (Th-based) derivatives have received wide attentions in organic optoelectronics due to their excellent and tuneable optoelectrical properties as well as chemical modification. However, the low photoluminescence quantum yield in solid state limits their application in solution-processed light-emitting optoelectronic devices, especially in organic lasers. Herein, a novel blue-emitting steric Th-based fluorophore (MC8-Th) with excellent optical gain behavior for organic laser is reported. Interestingly, MC8-Th neat film exhibits efficient exceptional deep-blue amplified spontaneous emission (ASE) behavior with a remarkably low threshold of 6.0 μJ cm?2 and full-width-at-half-maximum value of 2.6 nm. Furthermore, random laser signals are also obtained with the lowest threshold of 4.1 μJ cm?2 when incorporating the compound into an inert polystyrene (PS) matrix. In addition, low threshold (16 μJ cm?2, fivefold lower than those of F8BT neat films) yellow–green ASE emission (560 nm) is achieved through F?rster resonance energy transfer. Meanwhile, ultrafast transient absorption spectroscopy is deployed here to observe the single-molecular excitonic behavior in solution and PS-blend, intermolecular excited state in neat film, and efficient energy transfer in MC8-Th:F8BT-blend films. As far as known, MC8-Th shows lower threshold ASE/lasing behavior for the Th-based conjugated materials.
关键词： transient absorption spectroscopy,optical gain behavior,organic laser,thiophene-based derivatives,F?rster resonance energy transfer
更新于2025-09-23 15:19:57
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Laser oscillation at an intended wavelength from a distributed feedback structure on anisotropic organic crystals
摘要： An organic laser device is constructed as distributed feedback (DFB) type using an anisotropic single crystal of an organic semiconductor oligomer BP3T. The DFB structure is formed on top of the crystal via an interference exposure technique of a positive type photoresist. In the DFB structure, both the phase matching condition and waveguide condition must be fulfilled. Under these conditions, the effective refractive indices can be precisely predicted for a BP3T crystal, and they vary depending upon the crystal thickness. As a result, the device produces a single-mode laser oscillation at an intended wavelength (typically ～569 nm). The present study enables us to design a down-to-earth laser device based on an anisotropic organic semiconductor crystal toward practical use.
关键词： organic laser,single-mode laser oscillation,anisotropic organic crystal,BP3T,distributed feedback
更新于2025-09-19 17:13:59
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Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers
摘要： Organic single crystals with long-range molecular order ensure enhanced carrier mobility and stability as well as emission outcoupling, which makes them attractive as gain medium for electrically pumped organic lasers. Unfortunately, effects of excitonic coupling introduce losses degrading optical performance in crystals, hence higher lasing thresholds are observed compared to amorphous films. Here, crystal doping strategy is investigated as a method to avoid pronounced reabsorption and annihilation losses associated with J-type excitonic coupling, while taking advantage of enhanced exciton transport for efficient energy transfer. Bifluorene-based derivatives linked with acetylene and ethylene rigid bridges are suitable as host and dopant system forming high-quality crystals doped at various concentrations (0.5–11.0%). Enhanced exciton transport in host crystal mediates picosecond host–dopant energy transfer enabling 100% transfer efficiency at lower doping concentrations compared to amorphous films. Amplified spontaneous emission threshold of 1.9 μJ cm?2 in 3.5% doped crystal is enabled by minimized exciton annihilation and emission reabsorption losses at optimal doping concentration.
关键词： long-range energy transport,organic single crystals,organic laser gain materials,amplified spontaneous emission,F?rster resonant energy transfer
更新于2025-09-12 10:27:22
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Polarized Species in an Organic Semiconductor Laser
摘要： Meeting the challenge of direct electrically driven organic semiconductor lasers (OSLs), the design of OSL materials is under concern. Polarized species generally exist in conjugated organic materials and play an important role in the photophysics procedure; therefore, understanding these species is beneficial to designing novel OSL materials. Here, we use the amplified spontaneous emission effect as a medium to reveal a carbazole-benzothiadiazole-based polarized species that induced by charge transfer process. Spectroscopic analysis confirms that this polarized species that acted as a CT pair defect brings negative influence to both the ASE stability and solid state fluorescent quantum yield. It inspires us to be cautious for some specific molecular group combinations when designing OSL materials.
关键词： polaron,organic laser,carbazole,amplified spontaneous emission,charge transfer
更新于2025-09-12 10:27:22