Effects of Optical Confinement in Textured Antireflection Coating using ZnO Films for Solar Cells

Abstract

The effect of optical confinement in textured antireflection coating (AR coating) was investigated. Textured ZnO films prepared by metalorganic chemical vapor deposition were applied to solar cells as AR coating. The reflectance of the cells decreased as the grain size increased with film thickness, especially at long wavelength. This reduction in the reflectance caused an increase in short-circuit current and spectral response of the cells at near-infrared. The effect of optical confinement in the cell by this film was shown as far as long-wavelength range was concerned.

Biomimetic parabola-shaped AZO subwavelength grating structures for efficient antireflection of Si-based solar cells

“…Furthermore, the thin film ARCs allow only narrow bands of incident angles and wavelengths [12]. Various structures such as textured ZnO films, ZnO nanostructures (e.g., nanorods, nanowires, and nanotips), and ZnO pyramidal arrays, which produce a gradient-refractive-index profile between the ZnO and air, depending on the volume fraction, were demonstrated for ZnO ARCs [13][14][15][16][17][18][19]. Unfortunately, most of these nanostructures are disordered, which makes it somewhat difficult to control and obtain the desired refractive index profile for efficient ARCs, and often gives rise to light scattering.…”

Low temperature growth of highly transparent c-axis oriented ZnO thin films by pulsed laser deposition

“…When c-axis oriented, it also exhibits large piezoelectric and piezooptic coefficients [9-111. These qualities have attracted considerable interest in recent years with thin ZnO films being used in acoustoelectric and acoustooptic devices [12], solar cells [13], liquid crystal displays, gas sensors and window coatings [ 14-171. Many of the major deposition techniques for obtaining thin films have been employed to grow ZnO, including sputtering [2,4-6, 8, 161, chemical vapour deposition (CVD) [7,151, and chemical spraying [3].…”

Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

“…While the metal back-contact layer is necessary for collection of photo-generated carriers, it also helps to increase the light absorption by increasing the path length as the incident light bounces back [22]. The anti-reflection coating layer on the top increases the coupling of the incident light to the solar cell [23]. The metal fingers on the top of anti-reflection coating layer creates a shaded region in active layer, and thereby, reduces the light absorption by ∼10% [24].…”

“…The metal fingers on the top of anti-reflection coating layer creates a shaded region in active layer, and thereby, reduces the light absorption by ∼10% [24]. The effects of the metal back-contact layer, the anti-reflection coating layer, and the metal fingers are well known and have been investigated in detail [22][23][24].…”