Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

Abstract

We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

Metasurface Absorbers with Film-Coupled Au Nanoclusters to Achieve Broadband and Polarization-Independent Absorption of UV–Vis Light

“…The simulated results (Figure S3) exhibit that relatively poor (average absorbance below 70%) and narrow bandwidth absorptions were obtained in the UV–vis spectral range, with low densities and small areas of E-field distributions surrounding the Au NCs or Au film (see the insets a and b of Figure S3) due to the lack of the multiple surface plasmon resonances. In addition, it is important to point out that the “V”-shaped structures from Au NCs induced a positive light-trapping effect to reduce the incident surface reflection, , which would be conducive for designing MAs with excellent absorption properties. Specifically, the Au NCs present hierarchical architectures, which are composed of many “V”-shaped branches reaching in different directions.…”

Anti-Reflective Coating Materials: A Holistic Review from PV Perspective

“…Recently, ZnO nanostructures have been employed on various solar cells to impart AR properties (amorphous-Si [284,285], sc-Si [286][287][288], mc-Si [289], GaAs [290]). Lin et al deposited syringe-shaped ZnO nanorods on multi-crystalline silicon photovoltaic cells by a two-step aqueous solution process and obtained an efficiency enhancement of nearly 41% with a value of 17.61% when compared to those of bare surface [172].…”

Improvement of Amorphous Silicon Thin-Film Photovoltaic Cells with Zinc Oxide Nanorods

“…Therefore, increasing the optical path length in the absorbing layer causes an increase in light absorption. However, this method cannot easily control the surface structure morphology, which limits its future development [19]. Many studies have reported the use of a ZnO nanostructure for applications in devices.…”