| Constructing light-emitting display devices with high color purity,wide color gamut and high efficiency is a great pursuit for the information age.The material of metal-halide perovskite,owing to its excellent optoelectronic properties such as tunable emission range,high photoluminescence quantum yield(PLQY)and long carrier diffusion length,has become a promising candidate for building next-generation optoelectronic devices.Presently,the film-type perovskite devices have made remarkable progress and the external quantum efficiency(EQE)of green and red perovskite light-emitting diodes(PeLEDs)devices has exceeded 20%.However,the array-type devices that play an important role in display and integrated optoelectronics are still in the early-stage research.There are many challenges to be concerned,including exploring new methods to prepare patterned structures compatible with state-of-the-art microelectronics processes,which enable to avoid the degradation of perovskites during the procedures and facilitate the commercial application;fully understanding the excitonic properties of perovskites with different phases,which is crucial to design and optimize novel devices.In this context,we carried out the systematic research on the growth regulation of CsPbBr3 micrometer-scale single crystal arrays,characterization of the exciton,and fabrication of array PeLEDs devices in this dissertation.In chapter two,we prepare successfully single-crystal CsPbBr3 microarray by the method of hollow template-confined solution crystallization.The high single-crystal structures,uniform of morphologies and PL intensity are systematically confirmed by transmission electron microscopy(TEM),second harmonic generation(SHG),atomic force microscope(AFM),and photoluminescence(PL)spectroscopy.The universality of this method for various substrates is also demonstrated experimentally.Moreover,an efficient approach highly compatible with the state-of-the-art microelectronics processes is developed to construct PeLED device with 62 × 47 arrays.The array device has a pixel density of up to 1270 ppi(pixels per inch)and achieves a 99%high working ratio.A prototype PeLEDs display using this arrays is also demonstrated.In chapter three,we propose an optimized method of the template-confined solution crystallization with the assistance of special surface modifiers.The well-aligned single-crystal CsPbBr3 microarray with a preferential out-of-plane[100]orientation is achieved.The array grown at low temperature(60℃)is characterized by TEM,X-ray diffraction(XRD)and scanning electron microscopy(SEM),and the good crystalline qualities of arrays with cubic phase and good stability are demonstrated.Furthermore,by crystal growth regulation with different modifier variate,combined with Lewis acids and bases theory and principle of surface engineering,a reasonably underlying growth mechanism is revealed.In chapter four,we investigate thoroughly the excitonic properties of CsPbBr3 single crystals with different phases using various PL characterizations.It is found that,compared to the orthorhombic crystal,the cubic one has a low-threshold for lasing and its PL internal quantum efficiency(IQE)is also increased by 45%.Even both samples show the defect bound excitons and free exciton,the exciton-phonon interaction is distinctly different,which can be manifested by the different dependence of the emission peak position,the full width at half-maximum(FWHM)and the PL intensity with temperature.The PL spectrum of cubic single crystal possesses narrower FWHM and weaker phonon scattering,corresponding to its higher crystal quality and fewer defect states.In chapter five,we characterize the properties of PeLEDs constructed by the modifier-optimized CsPbBr3 single-crystal arrays.Compared to the device reported in chapter two,the optimized device shows comprehensive performance improvements with higher luminescence uniformity,4 times the luminescence intensity,and 3.4 times the EQE. |
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