Optimization Design Of Photonic Crystal Structure For Electroluminescence Device Based On PbS Quantum Dots

Having a periodic permittivity and dielectric constants in the optical wavelength magnitude, the photonic crystal can control the light propagation as required. In recent years, the photonic crystal finds wide application in photonic waveguide devices, laser and luminescent device. As a key material in infrared devices, PbS quantum dots have attracted much attention because of its better chemical stability and high carrier mobility. But its light loss from reflection at the interfaces remains limitation on overall efficiency of1.6%when it was used in electroluminescence device. In this thesis, a simulation of photonic crystal is hypothetically introduced into PbS quantum dots electroluminescence device to optimizing the luminescent efficiency. The details are described as follows:1、The influence of the photonic band gap effect on the light propagation direction is focused. The band structure of photonic crystal with circle/square (dielectric/air) which is arranged in triangle, square and hexagonal lattices are calculated by using the plane-wave expansion method. The relationship between the structure parameter and the complete band gap is obtained. The result shows that the photonic crystal with square dielectric column in hexagonal lattice has the biggest complete band gap at l/a=0.35. The frequency width of the biggest complete band gap△ω is at0.095(2πc/a), the lowest frequency ωmin at0.355(2πc/a), the highest frequency ωmax at0.45(2πc/a), the middle frequency f(a/λ) at0.403. The photonic crystal can modulate light propagation with wavelength from1004nm to1273nm when lattice constant a=452nm, side length of square dielectric column1=159nm, the light loss will be decreased for the light propagation is confined to the vertical direction.2、Combining with grating diffraction theory and the effective medium theory, the structure parameter of the photonic crystal is optimized to enhance the efficiency of the device to be57.9%, when the lattice constant a is at452nm, side length of square dielectric column l at159nm and the height h at200nm.3、The simulation view of light propagation with wavelength at1124nm is obtained by finite element method.