Efficient photon capturing with ordered three-dimensional nanowell arrays.

Unique light-matter interaction at nanophotonic regime can be harnessed for designing efficient photonic and optoelectronic devices such as solar cells, lasers, and photodetectors. In this work, periodic photon nanowells are fabricated with a low-cost and scalable approach, followed by systematic investigations of their photon capturing properties combining experiments and simulations. Intriguingly, it is found that a proper periodicity greatly facilitates photon capturing process in the nanowells, primarily owing to optical diffraction. Meanwhile, the nanoengineered morphology renders the nanostructures with a broad-band efficient light absorption. The findings in this work can be utilized to implement a new type of nanostructure-based solar cells. Also, the methodology applied in this work can be generalized to rational design of other types of efficient photon-harvesting devices.

Strong light absorption of self-organized 3-D nanospike arrays for photovoltaic applications.

Three-dimensional (3-D) nanostructures have been widely explored for efficient light trapping; however, many of the nanostructure fabrication processes reported have high cost and/or limited scalability. In this work, self-organized 3-D Al nanospike arrays were successfully fabricated on thin Al foils with controlled nanospike geometry such as height and pitch. Thereafter, photovoltaic materials of a-Si and CdTe thin films were conformally deposited on the nanospikes structures thus forming 3-D nanostructures with strong light absorption over a broad wavelength range and photon incident angle. Specifically, 100 nm-thick CdTe film on nanospikes showed 97% peak absorption, and up to 95% day-integrated sunlight absorption. These results indicate that self-organized 3-D Al nanospike arrays can serve as lightweight and low cost substrates for cost-effective thin film photovoltaics.