Organic Electrically Pumped Green Laser Based On Quasicrystal Microcavit

With the advantages of tunable spectrum,simple fabrication and flexible integration,organic semiconductor laser has a wide range of application prospects in the development of small tunable laser,flexible display lighting and other fields.At present,the main bottleneck restricting the development of organic semiconductor laser is the high device loss,including optical loss and exciton non-radiation loss.These losses lead to a higher laser threshold for organic semiconductor lasers,which limits the development of device applications.The aim of this paper is to make use of the excellent luminous properties of organic polymers and the unique local model selection of photonic crystals to prepare a single point output electropumped low threshold organic photonic crystal microcavity laser.On this basis,wavelength tunable photonic crystal lasers are designed based on polymer electro-optical effect.The main results of the paper are as follows:(1)OLED devices based on organic fluorene polymers PFO and F8T2 were studied,and the photoelectric characteristics of the two materials were analyzed.The results show that the current density of F8T2-OLED is one order of magnitude higher than that of PFO-OLED,and the brightening voltage of F8T2-OLED is lower.Both kinds of fluorene polymers have the phenomenon of red shift of electroluminescence peak relative to photoluminescence peak,especially PFO polymer.The redshift phenomenon comes from the effect of applied electric field on the molecular chain of fluorene polymer.Therefore,we put forward the prospect of further research on the luminescence peak redshift phenomenon by chemical simulation software from the perspective of organic molecular chain fracture and molecular chain Angle deflection.(2)An electropumped low threshold octet quasicrystal laser based on organic polymer material F8T2 is studied.Compared with periodic photonic crystals,the quasicrystalline structure has rotation symmetry,and it is easy to obtain complete photonic band gap and abundant defect mode at low refractive index pairs of organic materials.Therefore,the laser makes use of the local defect mode optical field of the octuple quasicrystal microcavity in the horizontal direction,and absorbs and captures the surrounding same-mode photons to further improve the density of state in the cavity.In the vertical direction,the sandwich structure of ITO/gain medium/metal film layer is constructed to achieve longitudinal optical gain resonance amplification.Aiming at the electroluminescence spectra of F8T2-OLED devices,the influences of structural parameters such as crystal lattice constant and crystal radius on photonic band gap and defect mode were systematically analyzed.Finally,the organic electropumped low-threshold photonic crystal microcavity laser with laser wavelength of 534.3 nm,half-height and width of 0.9 nm and threshold current of 0.6mA were prepared experimentally.(3)We designed a tunable photonic crystal laser with double-layer thin film based on the electro-optical effect of polymer and studied the effect of electro-optical polymer characteristics on the tuning efficiency.The results show that the thickness of the film is negatively correlated with the tuning efficiency.At the electro-optical coefficient of 150 pm/V,the laser tuning efficiency can reach 52.3pm/V.The results of this paper lay a theoretical foundation for the preparation of continuously tunable organic electropumped lasers in subsequent experiments.