| Laser has been widely used in many fields such as information technology,medical treatment,sensing detection and military weapons due to its high brightness,high monochromaticity and high coherence,and it is one of the essential inventions in the development of human society.Dye lasers with organic dyes as the working medium have become the most successful laser systems because organic materials have a microscopic four-level structure and a wide operating wavelength,which can achieve a wide range of tunable laser output.In recent years,the use of organic micro-nano crystals to combine the working medium with the resonant microcavity to develop an organic solid micro-nano laser is gradually becoming a research hotspot.Organic micro-nano lasers have attracted extensive attention of scientists in the research of holographic data storage and laser display.Organic dyes in organic micro-nano lasers have large wavelength coverage and excellent luminescence properties in solution,but most of them lose their luminescence efficiency in solid state due to aggregationinduced strong exciton coupling,which is manifested as fluorescence quenching,color shift and quantum yield decrease.These phenomena seriously limit the development of organic solid micro-nano lasers.Therefore,the construction of solid-state microlasers with high concentration of dye molecules that can suppress the self-quenching effect urgently requires new organic laser materials and new assembly strategies.The spatial isolation strategy of luminescent molecules is an effective means to avoid the quenching effect between dye molecules.The host-guest materials are combined through weak interactions such as hydrogen bonding,π-π stacking,electrostatic force and hydrophobic effect to provide isolation space for organic laser dye molecules.Fundamentally weaken the aggregation effect and achieve high fluorescence quantum yield,thereby improving the luminescence and gain efficiency of solid-state organic lasers.At the same time,the luminous efficiency and laser threshold are optimized by using the greater assembly freedom and adaptability of hostguest organic semiconductor materials.Furthermore,the intramolecular charge transfer can be used to control the emission wavelength of the polycrystalline state to construct a wavelength-adjustable crystal laser.Further,organic circularly polarized laser materials can also be designed by introducing chiral guest molecules to combine organic lasers with circularly polarized luminescence,which has attracted much attention at present,so that it can play a valuable role in the fields of organic circularly polarized lasers and 3D displays.The specific research contents of this paper included:1.Amplified spontaneous emission(ASE)study of cyanostar(CS)and organic laser dyes host-guest.A large number of microcrystals were prepared by solvent evaporation method using CS molecules reported in the literature and organic cationic laser dyes R6 G,DOC,DTC and Cyanine in a ratio of 2:1.The amplified spontaneous emission properties of this host-guest cocrystal microcrystalline structure were characterized.In this study,an obvious ASE phenomenon was observed for the first time in solid-quenched organic dyes,and the universality of this method was verified by multiple dyes.2.The solvatochromism and polymorph study of distyrylbenzene(DSB)derivatives.Phenothiazine,phenoxazine and 9,9-dimethylacridine containing heteroatoms and conformational changes were introduced into the DSB skeleton as side chains,and their fluorescence properties in different solvents were studied,respectively.It was found that the solvatochromism of DSB-PTZ and DSB-PXZ was more obvious than that of DSB-DMAC,which could reach a change of about 88 nm.Subsequently,several single crystals were prepared under the volatilization of different solvents.According to these single crystal datas,micro-area spectroscopy and basic photophysical properties,it was proved that the same molecule can obtain several single crystal structures with different emission wavelengths due to conformational changes and intramolecular charge transfer.And these crystal edges have bright fluorescence emission,with good optical waveguide effect,which is expected to achieve wavelength tunable organic lasers.3.Synthesis and characterization of chiral distyrylbenzene(DSB)derivatives.(R/S)-DSB-PEA molecules were designed and synthesized by introducing chiral phenylethylamine as a side chain into the DSB skeleton.High-quality microcrystals were prepared by the method of controllable precipitation in solvent atmosphere,and the basic optical characterization of the microcrystals proved that they had good solidstate luminescence properties.The chiral characteristics of the molecule in solution and solid state were verified by circular dichroism spectroscopy.By collecting the emission spectrum at different pump energies,it is found that the full width at half maxima of the emission spectrum is obviously narrowed,which proves the ASE characteristics and provides an important basis for further study of its circularly polarized laser characteristics. |
