Efficient Light Absorption by GaN Truncated Nanocones for High Performance Water Splitting Applications

Abstract

Despite the importance of gallium nitride (GaN) nanostructures for photocatalytic activity, relatively little attention has been paid to their geometrical optimization on the basis of wave optics. In this study, we present GaN truncated nanocones to provide a strategy for improving solar water splitting efficiencies, compared to the efficiency provided by the conventional geometries (i.e., flat surface, cylindrical, and cone shapes). Computational results with a finite difference time domain (FDTD) method and a rigorous coupled-wave analysis (RCWA) reveal important aspects of truncated nanocones, which effectively concentrate light in the center of the nanostructures. The introduction of nanostructures is highly recommended to address the strong light reflection of photocatalytic materials and carrier lifetime issues. To fabricate the truncated nanocones at low cost and with large-area, a dry etching method was employed with thermally dewetted metal nanoparticles, which enables controllability of desired features on a wafer scale. Experimental results exhibit that the photocurrent density of truncated nanocones is improved about three times higher compared to that of planar GaN.

A methodological review on material growth and synthesis of solar-driven water splitting photoelectrochemical cells

“…6). 42 The study theoretically and experimentally revealed that the truncated cone is the most appropriate for light trapping on the nanostructure close to the electrolyte reducing the path of photo-generated charges, in other words, a fast charge transport, and consequently showed an increase in the photocurrent. Furthermore, thermally dewetted metal particles for top-down structuring of a PEC cell with a truncated cone shape is a controllable and non-lithographical approach and thus, can reduce the fabrication cost.…”

“…This can be resolved by enhancing the STH efficiency and using nano-structures in PEC cells that are suitable for water splitting which could be an alternative route. 42 As briey mentioned in the PVD section, structuring the PEC cell can enhance light absorption and surface reactions thereby can possibly increase the STH efficiency. 30 However, the method addressed in ref.…”

Recent Progress in Gallium Nitride for Photoelectrochemical Water Splitting

“…The device also achieved high values of photocurrent of 0.32 mA/cm 2 by using etching voltages at 10 V (Figure 5e). Kim et al had prepared GaN truncated nanocones [76], which was shown in Figure 5c. GaN truncated nanocones have concentrated incident light inside the nanostructure and enhanced the light trapping with reduced light losses from surface reflection.…”

Double-Sided Anti-Reflection Nanostructures on Optical Convex Lenses for Imaging Applications

“…Anti-reflection coatings (ARCs) have been extensively studied in optoelectronics for efficient light management, such as in light-emitting diodes and solar cells exploiting the aforementioned functions. [7][8][9]. Numerous manufacturing processes have been developed with the increasing demand for ARCs.…”