Light absorption processes and optimization of ZnO/CdTe core–shell nanowire arrays for nanostructured solar cells

Abstract

The absorption processes of extremely thin absorber solar cells based on ZnO/CdTe core-shell nanowire (NW) arrays with square, hexagonal or triangular arrangements are investigated through systematic computations of the ideal short-circuit current density using three-dimensional rigorous coupled wave analysis. The geometrical dimensions are optimized for optically designing these solar cells: the optimal NW diameter, height and array period are of 200 ± 10 nm, 1-3 μm and 350-400 nm for the square arrangement with CdTe shell thickness of 40-60 nm. The effects of the CdTe shell thickness on the absorption of ZnO/CdTe NW arrays are revealed through the study of two optical key modes: the first one is confining the light into individual NWs, the second one is strongly interacting with the NW arrangement. It is also shown that the reflectivity of the substrate can improve Fabry-Perot resonances within the NWs: the ideal short-circuit current density is increased by 10% for the ZnO/fluorine-doped tin oxide (FTO)/ideal reflector as compared to the ZnO/FTO/glass substrate. Furthermore, the optimized square arrangement absorbs light more efficiently than both optimized hexagonal and triangular arrangements. Eventually, the enhancement factor of the ideal short-circuit current density is calculated as high as 1.72 with respect to planar layers, showing the high optical potentiality of ZnO/CdTe core-shell NW arrays.

ZnO/CuCrO2 Core–Shell Nanowire Heterostructures for Self‐Powered UV Photodetectors with Fast Response

“…The possibility to form ZnO NWs using various deposition techniques, including low‐cost and low‐temperature chemical bath deposition (CBD), and to take advantage of their unique properties has thus raised more interest. Within the core–shell NW heterostructure configuration, and following the type‐II band alignment, ZnO NW‐based heterojunction devices offer efficient light‐trapping processes through optically guided and radiated modes, efficient charge carrier separation over the small radius of the NWs, and efficient charge carrier collection owing to the high mobility electron pathways provided by the NWs . ZnO NW‐based core–shell heterostructures have successfully been integrated into gas sensors, UV photodetectors, as well as dye‐sensitized and extremely thin absorber solar cells .…”

Photonic crystals for optimal color conversion in light-emitting diodes: a semi-analytical approach

“…Such a finding can restrict substantially the parametric space of the considered LED coloring designs and simplify significantly the subsequent optimizations. Most importantly, if one is able to find, without computationally heavy schemes [31,41], a set with several candidate designs exhibiting ultra-high performance, one can perform a secondary sweep within this set by posing extra constraints or demands (cost, ease of fabrication, durability, etc. ).…”

Theoretical investigation about the optical characterization of cone‐shaped pin‐Si nanowire for top cell application

“…Michallon et al. , rigorously investigated the optical behavior of extremely thin absorber solar cells based on ZnO/CdTe core–shell nanowire (NW) arrays with square, hexagonal, or triangular arrangements, using three‐dimensional rigorous coupled wave analysis (RCWA). It was concluded that the light absorption is more efficient in the NW square arrangement than in the hexagonal and triangular arrangements .…”

“…There are several reports available on the optical modeling and simulation of different geometrical shapes, sizes, and materials. [42][43][44][45][46][47][48][49][50][51]. Few years ago, optical properties of c-Si nanohole array structures for solar photovoltaic applications were investigated [42] and it was found that the nanohole absorption is better than nanorod arrays for solar cells application.…”

“…One interesting research problem about tuning the UV emission of the ZnO-ZnS core-shell nanorod arrays by changing the index of the substrate were investigated [48], and it was concluded that the introduction of active host medium is responsible for the optical absorption, which was greater than the expected Lambert-Beer law [48]. Michallon et al [49], rigorously investigated the optical behavior of extremely thin absorber solar cells based on ZnO/CdTe core-shell nanowire (NW) arrays with square, hexagonal, or triangular arrangements, using three-dimensional rigorous coupled wave analysis (RCWA). It was concluded that the light absorption is more efficient in the NW square arrangement than in the hexagonal and triangular arrangements [49].…”