Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices

Abstract

Integrating devices with nanostructures is considered a promising strategy to improve the performance of solar energy harvesting devices such as photovoltaic (PV) devices and photo-electrochemical (PEC) solar water splitting devices. Extensive efforts have been exerted to improve the power conversion efficiencies (PCE) of such devices by utilizing novel nanostructures to revolutionize device structural designs. The thicknesses of light absorber and material consumption can be substantially reduced because of light trapping with nanostructures. Meanwhile, the utilization of nanostructures can also result in more effective carrier collection by shortening the photogenerated carrier collection path length. Nevertheless, performance optimization of nanostructured solar energy harvesting devices requires a rational design of various aspects of the nanostructures, such as their shape, aspect ratio, periodicity, etc. Without this, the utilization of nanostructures can lead to compromised device performance as the incorporation of these structures can result in defects and additional carrier recombination. The design guidelines of solar energy harvesting devices are summarized, including thin film non-uniformity on nanostructures, surface recombination, parasitic absorption, and the importance of uniform distribution of photo-generated carriers. A systematic view of the design concerns will assist better understanding of device physics and benefit the fabrication of high performance devices in the future.

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

“…Another way for coupling light into the ultrathin semiconductor film thicknesses is to employ trapping scaffolds . A trapping scaffold is a designed 3D patterns that provide a gradual matching between air and the device impedance.…”

Photo-reduced Cu/CuO nanoclusters on TiO2 nanotube arrays as highly efficient and reusable catalyst

“…These irregular arrays were ultrasonically removed in DI water and the same Ti foil was anodized again under 40 V for 1 h. After this second anodization, highly ordered and regular TiO 2 NT arrays were formed on top of the Ti foil. Compared to the irregular NT arrays, these two-step-fabricated highly ordered TiO 2 NT arrays can provide greater absorption of incident light31 and offer more suitable nucleation sites for metal nanoparticles during the photoreduction as discussed in our previous work30. The anodized TiO 2 substrates were rinsed with ethanol, dried with pure nitrogen and finally annealed in air at 480 °C for 3 h with a heating rate of 5 °C/min3032.…”

17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures

“…[1][2][3][4][5][6] Radial p-n junctions formed by core-shell structures exhibit efficient charge collection because minority carriers can be collected along the relatively short radial direction that is orthogonal to the long light absorption direction along the wire axis. [9][10][11] However, further research is required to realize highly efficient solar cells based on radial junctions because of certain limitations of each structure. 7,8 In addition, nano-and microwire arrays are expected to result in improved short-circuit current densities (J sc ) owing to increased light absorption from the efficient light trapping effect caused by multiple scatterings.…”