将PbS量子点电致发光器件的发光层引入二维光子晶体结构,利用光子晶体的光子带隙效应提高器件的发光效率。采用平面波展开法计算了以空气为背景,由圆形或方形介质柱所构成的不同晶格排列的光子晶格的能带图,获得光子晶体结构参数对完全带隙的影响规律。结果显示:采用方形介质柱以蜂窝方式排列的光子晶体在填充率.f=0.283时具有较宽的完全带隙△ω=0.1346(2πc/a)。利用有限元法模拟了晶格常数a=476nm,方形介质柱边长/=167nm时,波长为1124nm的光在该光子晶体中传播的光场分布图。计算得到具有该光子晶体结构的PbS量子点电致发光器件的发光效率可达57.9%。
The two-dimensional photonic crystal was introduced into the luminescent layer of PbS quantum dots (QDs) electroluminescence (EL) devices to improve efficiency by photonic bandgap effect. The energy band structure of photonic crystal with different array of PbS circular or square column was calculated by using plane-wave expansion method. The influence of photonic crystal parameters on photonic bandgap was discussed. The result shows that a relatively wider complete photonic bandgap △ω=0.1346(2πc/a) exists at the honeycomb-lattice photonic crystal structure which is consisted of PbS square column in air with the fill factor f=0.283. The three-dimensional simulation view of light with wavelength of 1 124 nm propagation in the photonic crystal is obtained by using the finite element method when square column length l is 167 nm and lattice constant a is 476 nm. The calculated device efficiency closes to 57.9% for the proposed photonic crystal structure.