ZnO Nanowires as an Antireflection Coating for Solar Cells: Angular Scattering Measurements
EMSL Project ID
44392
Abstract
Photovoltaic technology is rapidly changing. As traditional bulk materials give way to thin films, one of the greatest impacts on solar cell efficiency still remains in the optical properties of the cell. Optical coatings reduce reflective losses, allowing more light to be coupled into the cell. In traditional solar cells antireflective (AR) coatings are often paired with rough lambertian or geometric surfaces to create light trapping within the cell. New research has shown that optical coatings made of nanostructured material may achieve both phenomena, scattering of light and reduced broadband reflectance. In this study, ZnO nanowires are used as AR coatings for solar cells. In previous work, ZnO nanowires, either through tapering or random height variations, have been shown to create a continuously graded index of refraction which serves to optically couple light into a material.(1, 2) Results show reduced broadband reflection at normal incident light due to vertical nanowire. However, there have been limited studies on the dependence of reflection and scattering for different nanowire alignments and for oblique incidence, which mimics the directionality of sunlight. The facilities at PNNL allow for the total angular reflectance of diffuse, heterogeneous samples to be taken. By creating different alignments of ZnO nanowires, characterizing them using SEM images, and taking scattering measures, a better understanding of the scattering processes of nanowires will be achieved. Improving AR coatings will lead to more efficient solar cell. The creation of broadband, omnidirectional AR coatings for thin film and next generation solar cells supports PNNL's mission to research alternative energy technology such as thin film solar cell. The scattering of light off of nanowires exemplifies an interfacial phenomenon which is crucial to the efficiency of photovoltaic devices. 1 Chen, J.Y. and Sun, K.W., ''Growth of vertically aligned ZnO nanorod arrays as antireflection layer on silicon solar cells'',Solar Energy Materials & Solar Cells 94, 930-934 (2010). 2 Lee, Yun-Ju et al., ''ZnO Nanostructures as Efficient Antireflection Layers in Solar Cells'', Nano Letters, 8, 1501-1505 (2008).
Project Details
Project type
Limited Scope
Start Date
2011-04-21
End Date
2011-06-21
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Nadarajah A, and RF Koenenkamp. 2012. "Improved performance of Nanowire-Quantum-Dot-Polymer Solar Cells by Chemical Treatment of the Quantum Dot with Ligand and Solvent Materials." Nanotechnology 23(48):485403. doi:10.1088/0957-4484/23/48/485403