Enhancing Optically Pumped Organic-Inorganic Hybrid Perovskite Amplified Spontaneous Emission via Compound Surface Plasmon Resonance

Enhanced lasing properties of BUBD-1 film with multifunctional buffer layers doped with silver nanoparticles

The organic semiconductor lasers (OSLs) have been seen as a promising light source for future applications. Achieving organic semiconductors with low amplified spontaneous emission (ASE) threshold is a key progress toward the electrically pumped OSLs. In this paper, the ASE properties of CBP: 2wt% BUBD-1 blend films were optimized using buffer layers containing silver nanoparticles (Ag NPs) with different ratios. Both photoluminescence intensity and ASE properties of blend films were optimized when the buffer layer with 25 vol% Ag NPs was introduced. The lowest ASE threshold is 0.47 µJ/Pulse (6.71 µJ/cm²), which reduces 67.6%, and the highest gain factor is 20.14 cm^-1, which enhances 47.8% compared with that without buffer layers. The enhancement of ASE properties of blend films was ascribed to the four functions of the Ag NPs doped buffer layers, including the low refractive index of PMMA and the triple localized surface plasmon resonance (LSPR) effects of Ag NPs in buffer layers. The results show that the buffer layer modified by metal nanoparticles has great application potential in improving the lasing performance of organic small molecules.

Amplified Spontaneous Emission Threshold Dependence on Determination Method in Dye-Doped Polymer and Lead Halide Perovskite Waveguides

Nowadays, the search for novel active materials for laser devices is proceeding faster and faster thanks to the development of innovative materials able to combine excellent stimulated emission properties with low-cost synthesis and processing techniques. In this context, amplified spontaneous emission (ASE) properties are typically investigated to characterize the potentiality of a novel material for lasers, and a low ASE threshold is used as the key parameter to select the best candidate. However, several different methods are currently used to define the ASE threshold, hindering meaningful comparisons among various materials. In this work, we quantitatively investigate the ASE threshold dependence on the method used to determine it in thin films of dye-polymer blends and lead halide perovskites. We observe a systematic ASE threshold dependence on the method for all the different tested materials, and demonstrate that the best method choice depends on the kind of information one wants to extract. In particular, the methods that provide the lowest ASE threshold values are able to detect the excitation regime of early-stage ASE, whereas methods that are mostly spread in the literature return higher thresholds, detecting the excitation regime in which ASE becomes the dominant process in the sample emission. Finally, we propose a standard procedure to properly characterize the ASE threshold, in order to allow comparisons between different materials.

Enhanced electron transportation of PF-NR2 cathode interface by gold nanoparticles

In order to achieve a wider organic light-emitting diode (OLED) commercial popularity, solution processing inverted polymer light-emitting diode (iPLED) is a trend for further development, but there is still a gap for solution processing devices to achieve commercialization. The improvement of the performance iPLEDs is a research topic of intense current interest. The modification of the cathode interface layer of poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PF-NR₂) can greatly improve the performance of the devices. However, the electron transportation of the cathode interface layer of PF-NR₂ films is currently poor, and there is substantial interest in improving its electron transportation to further enhance the performance of organic optoelectronic devices. In this paper, gold nanoparticles (Au NPs) with a particle size of 20 nm were prepared and doped into the interface layer PF-NR₂ at a specified ratio. The electron transportation of the interface layer of PF-NR₂ was greatly improved, as judged by conductive atomic force microscopy measurements, which is due to the excellent conductivity of Au NPs. Herein, we demonstrate improved electron transportation of the interface layer by doping Au NPs in PF-NR₂ film, which provides important and practical theoretical guidance and technical support for the preparation of high performance organic optoelectronic devices.

Ultrastable CsPbBr3 Perovskite Quantum Dot and Their Enhanced Amplified Spontaneous Emission by Surface Ligand Modification

The poor stability and aggregation problem of CsPbBr₃ quantum dots (QDs) in air are great challenges for their future practical application. Herein, a simple and effective ligand-modification strategy is proposed by introducing 2-hexyldecanoic acid (DA) with two short branched chains to replace oleic acid (OA) with long chains during the synthesis process. These two short branched chains not only maintain their colloidal stability but also contribute to efficient radiative recombination. The calculations show that CsPbBr₃ QDs with DA modification (CsPbBr₃ -DA QDs) have larger binding energy than CsPbBr₃ QDs with OA (CsPbBr₃ -OA QDs), resulting in significantly enhanced stability. Due to the strong binding energy between DA ligands and QDs, CsPbBr₃ -DA QDs exhibit no aggregation phenomenon even after stored in air for more than 70 d, and CsPbBr₃ -DA QDs films can maintain 94.3% of initial PL intensity after 28 d, while in CsPbBr₃ -OA QDs films occurs a rapid degradation of PL intensity. Besides, the enhanced amplified spontaneous emission (ASE) performance of CsPbBr₃ -DA QDs films has been demonstrated under both one- and two-photon laser excitation. The ASE threshold of CsPbBr₃ -DA QDs films is reduced by more than 50% and their ASE photostability is also improved, in comparison to CsPbBr₃ -OA QDs films.