Design and Preparation of Anti-Reflection Nanoarray Structure on the Surface of Space Solar Cell Glass Cover

Abstract

Space solar cell glass covers require high radiation resistance and wide-spectrum high light transmittance. The existing research on the preparation of thin films or special optical structures on the surface of solar cells rarely involves systematic research and the precise control of the high transmittance structural parameters of specific spectral bands by glass covers. Nanoarray structures were designed and constructed on high-purity quartz glass covers, achieving high anti-reflection within the 350–1100 nm range, the high energy part of the solar spectrum on Mars, regardless of the preparation of antireflective film and its radiation resistance. First, G-Solver software package was used to establish a nanoarray structure model according to the equivalent medium theory, and the effects of structural parameters such as the grating period, grating depth, and duty cycle on the glass cover transmittance were investigated. The results show that when the grating period is 50–200 nm, the transmittance ranges from 97.8% to 99.9%. When the grating period further increases from 300 nm, the lowest point of the transmittance spectrum moves to the longwave direction, and the transmittance from 350 nm to the lowest transmittance point significantly reduces. The optimal grating depth is 500 nm for a 300 nm grating period, the transmittance at 350 nm reaches 88.91%, and the average transmittance is 98.23%. When the period is 300 nm and the depth is 500 nm, the optimal duty cycle is 0.67, the transmittance at 350 nm reaches 96.52%, and the average transmittance is 99.23%. Nanoarray structures were constructed on the glass covers with nanoimprint and plasma etching, then modified with atomic layer deposition (ALD) to adjust their depth and duty cycle. The influence rules of the grating period, depth, and duty cycle on the cover transmittance from the experimental results are basically consistent with those from the simulation calculation. The nanoarray structure increases the average transmittance within 350–1100 nm of the glass cover by an average of 2.02% and the peak transmittance by 2.66%. The research results and experimental methods of this study have application value and promotion prospects for improving the photoelectric conversion efficiency of space solar cells and ground solar cells.

Modeling of the synergistic anti-reflection effect in gradient refractive index films integrated with subwavelength structures for photothermal conversion

“…To describe the anti-reflection performance of subwavelength structures or multilayer anti-reflection coatings, we here use the admittance recursion method (based on the equivalent medium theory) rather than the transmission matrix method (TMM) 29,30 and finite-difference time-domain method (FDTD) 31 since it has proved to be accurate to calculate the reflectance of subwavelength structures at any wavelength or angle of incidence. 13,32 In our case, it not only adequately meets the design requirements for fine-tuning the shapes and structural parameters of subwavelength structures, but also fits for the calculation of multilayer gradient refractive index films, thereby satisfying a comprehensive algorithm for this model. The flow diagram of the simulation and design of the whole device is shown in Fig.…”

“…Firstly, the sensitivity relationship between reflectance and the structure as well as the arrangement parameters of SNAs is studied by employing common glass as the substrate (n = 1.52, close to SiO 2 ), 13 The anti-reflection capabilities of cylinder, cone, paraboloid, and pyramid subwavelength structures, which have garnered considerable attention from many researchers, [37][38][39][40] are initially investigated through the admittance recursion method (Fig. 1 Since the admittance recursion method cannot directly solve the electromagnetic vector distribution for periodic subwavelength structures, it is first necessary to employ equivalent medium theory to approximate periodic subwavelength structures as a multilayer film system, as depicted in Fig.…”

“…In this context, the two-dimensional duty cycle, f 2 , represents the filling factor. For a periodic subwavelength structure with height H, the effective refractive index at a distance h from the bottom surface of the structure can be expressed as: 13 n e ðhÞ ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi…”

“…According to the equivalent medium theory, each layer can be viewed as a uniform optical film without considering diffraction. 13,[46][47][48] Thus, only transmission and reflection are considered in this admittance recursion model.…”

“…To minimize the residual reflectance caused by the inhomogeneity of refractive index, a novel design of SNA with excellent light-trapping performance is proposed based on the equivalent medium theory. 13 Furthermore, the admittance recursion model is extended to the design of gradient refractive index transparent ceramics, thus developing a complete algorithm for the design of this anti-reflection system. Genetic algorithm (GA), 14 particle swarm algorithm (PSO), 15 simulated annealing algorithm (SA), 16 and the quintic index distribution method (QID) 17 are employed respectively to optimize the structures of GRITCs, followed by a comprehensive analysis and comparison of these methods.…”