| In the past years,organic-inorganic hybrid perovskites have been widely utilized in optical and optoelectronic devices,due to the excellent photoelectric properties.As a wide-bandgap semiconductor,organic-inorganic hybrid perovskites have also shown excellent nonlinear optical properties.In this thesis,large-area and high-quality organic-inorganic hybrid perovskite monocrystalline films have been fabricated for further study.The two-photon-absorption-induced photoluminescence(TPL)from organic-inorganic hybrid perovskite monocrystalline films have been studied,and strategies were also proposed to enhance the TPL property.Moreover,we also explored some related applications of the TPL properties of the from organic-inorganic hybrid perovskite monocrystalline films,such as super-resolution imaging and nanolasers.The following aspects have been mainly studied in this thesis:(1)The TPL property of a typical 2D perovskite(PEA)2PbI4 was studied,and the TPL emission can be enhanced by two orders of magnitude with a hybrid dielectric structure composed of 2D perovskite and microsphere.The theory of nonlinear optics indicates that the TPL intensity is on quadratic power dependence of the excitation intensity.The incident laser beam can be focused by a dielectric microsphere onto the sample within a subwavelength resion,thus leading to a great enhancement of the field intensity.As a result,the TPL intensity of the(PEA)2PbI4 monocrystalline films can be enhanced by two orders of magnitude in the hybrid dielectric structure.Calculated simulations reveal that,the main mechanism of the TPL enhancement in hybrid dielectric structure dominantly originates from the nanofocusing of the excitation field and the improvement of the TPL collection efficiency.Then,the influence of the structural parameters of the hybrid dielectric structure on the TPL enhancement was investigated in detail,including the size of microspheres,the refractive index of microspheres and the array structure.For practical applications,the TPL-based super-resolution imaging is demonstrated by utilizing the hybrid dielectric structure.The TPL emission of the hybrid dielectric structure was acted as the micro-nano light source,and the microsphere was acted as the superlens.These results show that the hybrid dielectric structure provides a simple and effective approach to enhance the TPL emission of organic-inorganic perovskites,which shows great promise for applications in nanophotonics.In addition,the second harmonic generation of a WS2 monolayer can be enhanced by more than 20 times by the hybrid dielectric structure,which was used for an optical refractive index sensor with high sensitivity.(2)The TPL of MAPbBr3 perovskite monocrystalline films was studied,and a two-photon pumped high-quality vertical-cavity surface-emitting laser(VCSEL)was realized.Large-area,high-quality MAPbBr3 monocrystalline films were prepared by a method of pressure supersaturation deposition.After that,a VCSEL was fabricated by integrating MAPbBr3 monocrystalline films with high-quality distributed Bragg reflector(DBR)mirrors.Under two-photon pump,the VCSEL shows a single longitudinal mode property,a low lasing threshold(?421?J/cm2),a high Q factor(?1286),a small far-field divergence(?0.5°),and a good spatial coherence.Furthermore,taking advantage of the anisotropic two-photon absorption of the MAPbBr3 perovskites,a switchable property of the VCSEL can be demonstrated by tuning the polarization of the pump.In addition,strong coupling interaction between photons and excitons was also observed in the microcavity structure,which shows a Rabi splitting energy of 353 me V.(3)The TPL properties and amplified spontaneous emission(ASE)of the Ruddlesden-Popper perovskite(quasitwo-dimensional perovskite)monocrystalline films were studied.High quality(BA)2(MA)n-1PbnI3n+1(n=1,2,3,4,5)perovskite crystals were synthesized by the method of solution supersaturation deposition,and(BA)2(MA)n-1PbnI3n+1monocrystalline films were obtained by mechanical exfoliation.Under the two-photon pump,the TPL intensities of(BA)2(MA)n-1PbnI3n+1(n=3,4,5)perovskite films decrease with the excitation wavelength,because the energy transfers to a third-harmonic generation(THG)process.The TPL of the(BA)2(MA)n-1PbnI3n+1 perovskite monocrystalline film also shows an anisotropy with the excitation polarization.The anisotropic coefficient increases as n,which indicates that the TPL anisotropy of the Ruddlesden-Popper perovskites can be precisely controlled by adjusting the proportion of two-dimensional and three-dimensional organic chain.In addition,the ASE process was also demonstrated in the(BA)2(MA)n-1PbnI3n+1(n=3,4,5)films at room temperature.The threshold of the ASE decreases with the excitation wavelength. |
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