Research On Organic - Inorganic Hybrid Semiconductors That Emit Direct White Light

White LED (Light-emitting diodes) convert electricity to light much more effectively than conventional lighting sources. They contribute to energy conservation and reduction of green house gases and offer a cleaner environment. Additionally, with the excellent performance such as long lifetime, small size, fast response and impact resistance, they have been considered to be the fourth illumination source after incandescent lamp, fluorescent lamp and gas discharge lamp.Ⅱ-Ⅵorganic - inorganic hybrid semiconductors combined the advantages of organic compounds and inorganic semiconductors so that they can provide good transmission characteristics and high carrier mobility. With the purpose of overcoming the shortages of current preparation of white LED, simultaneously rising the research ofⅡ-Ⅵorganic - inorganic hybrid semiconductors from foundation to application, 2D-[Zn₂S₂(ha)] has been synthesized through solvothermal reaction in this paper. Through systematically tune its optical properties simply by doping Cd and Se respectively, as well as Cd and Se co-doping, a series ofⅡ-Ⅵorganic - inorganic hybrid semiconductors that can emit direct white light have been used to produce white light LED successfully.The influence of preparation conditions such as reaction time, temperature, the ratio of organic and inorganic materials on the structure and properties was investigated. The optimal conditions for synthesis in 50 ml vessel are as follows: temperature 120℃, reaction time 2 days, solvent volume (ha) 6 ml. The best Cd and Se content of individual doping are 15 mol% and 10 mol% respectively, and 10 mol% Se is appropriate in 20 mol% Cd doping materials, while 15 mol% is the best doping content of Se in 25 mol% Cd doping materials.Structural and optical properties were characterized by XRD, UV-vis and fluorescence. The results showed that all products belong to the same kind of two-dimensional structure, and by changing the composition and doping level can systematically tune their optical properties. Band gap decreased after doping, and the largest decrease of 1.3 eV with 25 mol% Cd doping. Fluorescence intensity and luminous range increased at first, then decreased when increasing the doping level. The largest fluorescence intensity and luminous range occurred at 15 mol% Cd doping material, which is more larger than 2D-[Cd₂S₂(ha)].After annealing at 450℃for 30 minutes, the product structures were destroyed, band gap decreased, and the fluorescence intensity dropped drastically.