All‐Solution‐Processed Random Si Nanopyramids for Excellent Light Trapping in Ultrathin Solar Cells

Abstract

Si nanopyramids have been suggested as one of the most promising Si nanostructures to realize high-efficient ultrathin solar cells or photodetectors due to their low surface area enhancement and outstanding ability to enhance light absorption. However, the present techniques to fabricate Si nanopyramids are either complex or expensive. In parallel, disordered nanostructures are believed to be extremely effective to realize broadband light trapping for solar cells. Here, a simple and cost-effective method is presented to form random Si nanopyramids based on an all-solution process, the mechanism behind which is the successful transfer of the generation site of bubbles from Si surface to the introduced Ag nanoparticles so that OH − can react with the entire Si surface to naturally form random and dense Si nucleus. For optical performance, it is experimentally demonstrated that the random Si nanopyramid textured ultrathin crystalline Si (c-Si) can achieve light trapping approaching the Lambertian limit. Importantly, it is revealed, by numerical calculations, that random Si nanopyramids outperform periodic ones on broadband light absorption due to more excited optical resonance modes. The finding provides a new opportunity to improve the performance of ultrathin c-Si solar cells with a simpler process and lower cost.

Lateral Photovoltaic Effect and Photo‐Induced Resistance Effect in Nanoscale Metal‐Semiconductor Systems

“…When irradiated by laser, the system with suitable thickness presents a conspicuous LPE with a high sensitivity (maximum reaches 157.9 mV·mm −1 ) as shown in Figure b. This surface morphologies of random nanopyramids bring a low surface recombination and more optical resonance modes, which cause a greater light harvesting (shown in Figure c) and benefit the performance of LPE a lot . The reference also displays a simulation of this system whose result is consistent with above statements as well.…”

Sidewall Profile Dependent Nanostructured Ultrathin Solar Cells With Enhanced Light Trapping Capabilities

“…6. It can be seen that in the short wavelength region (e.g., 0.3 μm), nanostructure provide Mie scattering resonance to enhance the absorption performance [52], [53], but strong surface reflection limits the increase of absorption. In the mid-band (e.g., 0.5 μm), besides the weak Mei scattering resonance and F-P resonance, the first-order diffraction of nanostructure also provides a strong optical waveguide mode, which greatly improves the absorption capacity of c-Si [54], [55].…”

Facile Fabrication of Micro/Nano Hierarchical SERS Sensor via Anisotropic Etching and Electrochemical Treatment for Malachite Green Detection

“…From the image, one can also see that the produced micro-pyramid array is a randomly sized pyramid array surface. This feature may be an advantage, as mentioned in [15], a random-sized pyramid array surface can have better light collection efficiency than a planar and single-sized pyramid array surface over a wide wavelength range. The average spacing between the micro-pyramids is about 2.8 µm, and the average width of the micro-pyramids at the base is about 1.4 µm.…”

“…An anisotropic wet chemical etch is typically utilized to form a micro-sized pyramidal structure as a light-harvesting structure using different etch rates of silicon crystals at <100> and <111> surfaces [14]. It has been shown that a randomly sized pyramid array surface can have better light-harvesting efficiency and therefore a better absorption coefficient than planar and single sized pyramid array surfaces [15]. In some SERS studies [7][8][9], It has been proven that the Si pyramids can increase the amount of the hot spots by providing large surface area and create strong local electric field [9].…”