Fabrication Of Antireflective Structures Based On The Self-assembled Monolayer Of Nanoparticles

To suppress the Fresnel reflection is an important method to improve utilization of incident light. This method can improve the photoelectric conversion efficiency of solar cells and optical sensitivity of the sensors. The Fresnel reflection of incident light comes from the refractive index discontinuity at the interface of two media, which severely limits the performance of optical and optoelectronic devices. The high reflective index of Si results in the reflection of up to 35% of the incident light, which severely affects photoelectric conversion efficiency.In order to suppress the interface reflection, researchers have made a lot of efforts. The most common method used in industries is a quarter wavelength of light. However, the stability problems induced by adhesiveness and thermal mismatch are often associated with such approaches. Increasing effort has been devoted to the fabrication of such surface antireflection structures. In order to seek for a method which provides a facile approach for producing antireflection surfaces on large areas with low cost and high throughput, this paper mainly investigate on the following three aspects:We investigate what effect different etched morphologies have on antireflective properties.2D polysterene (PS) sphere array was prepared on a Si substrate. Structures with different morphologies can be obtained by changing the etching conditions, which help us to obtain Si nanopillar structures. By adjusting the etching conditions we can obtain nanopillars with different aspect ratios. We investigate the effects of aspect ratio and periodicity on antireflective property.The substrate materials seriously affect the antireflective property. Herein we investigate antireflective properties of different substrate materials. Two different kinds of substrates are discussed here:transparent substrate and light-absorbing substrate (opaque substrate). Since A+R+T=1 (A:absorption, R:reflectivity, T: transmission), the antireflective energy increases the transmission of light for the transparent substrate, instead it increases the absorption of light for the opaque one.The energy release form of antireflective structure whose substrate contains fluorescent dye also investigated. Spin-coating polymer containing dye molecules on the quartz substrate initially, then antireflective structure containing fluorescent dye is obtained in an imprinting process by using the antireflective structure as a stamp. We investigate the relationship between absorption spectroscopy and reflection spectroscopy, and then the relationship between fluorescence emission spectrum, absorption spectroscopy and reflection spectroscopy is obtained. We can conclude that the antireflective energy can be absorbed by fluorescent dye, whose fluorescence emission intention is increased while the fluorescence quantum efficiency is constant.In summary, we demonstrate antireflective structures with different periodicities on different substrates, which is based on the combination of self-assembly and reactive-ion etching. The effects of periodicity and materials of antireflective property are investigated in detail. Further research on the release form of antireflective energy is still being carried on, which provides theoretical basis for the fabrication of optical sensor.