Characteristics of large‐scale nanohole arrays for thin‐silicon photovoltaics

Abstract

Nanostructured crystalline silicon is promising for thin‐silicon photovoltaic devices because of reduced material usage and wafer quality constraint. This paper presents the optical and photovoltaic characteristics of silicon nanohole (SiNH) arrays fabricated using polystyrene nanosphere lithography and reactive‐ion etching (RIE) techniques for large‐area processes. A post‐RIE damage removal etching is subsequently introduced to mitigate the surface recombination issues and also suppress the surface reflection due to modifications in the nanohole sidewall profile, resulting in a 19% increase in the power conversion efficiency. We show that the damage removal etching treatment can effectively recover the carrier lifetime and dark current–voltage characteristics of SiNH solar cells to resemble the planar counterpart without RIE damages. Furthermore, the reflectance spectra exhibit broadband and omnidirectional anti‐reflective properties, where an AM1.5 G spectrum‐weighted reflectance achieves 4.7% for SiNH arrays. Finally, a three‐dimensional optical modeling has also been established to investigate the dimension and wafer thickness dependence of light absorption. We conclude that the SiNH arrays reveal great potential for efficient light harvesting in thin‐silicon photovoltaics with a 95% material reduction compared to a typical cell thickness of 200 µm. Copyright © 2012 John Wiley & Sons, Ltd.

Incident light adjustable solar cell by periodic nanolens architecture

“…Overall, the ITO-nanolens device has higher internal quantum efficiency (IQE) values for the broad wavelengths than did the planar device (Fig. 4e); this situation was different from that of the direct Si-etched structure1252. A clear comparison of the two devices according to wavelength can be seen by plotting the relative IQE values of the ITO-nanolens over those of the ITO film (Fig.…”

Silicon Quasi‐One‐Dimensional Nanostructures for Photovoltaic Applications

“…As for the SiNWs, the passivation process is a critical step and it has been addressed in the literature with several solutions. The SiNHs surface can be passivated with a defects removal etching (DRE) process, with the objective to remove the ion bombardment defects [31]. The DRE process is performed onto the sample using an oxidant aqueous solution of HF:HNO 3 which works through two different steps: (1) nitric acid oxides Si to SiO 2 and (2) HF removes the oxide formed.…”

“…The size of the holes obtained is strictly related to the metal amount, substrate orientation, and etching duration [11,21,30]. The roughness left by the etching process is well recognized in the literature as an issue for the application of solar cells because of its impact on the carrier recombination, thus different surface passivation procedures are developed [11,31]. UV lithography merged with the MAE etch is proposed in the literature as one of the most conventional strategies for the synthesis of an ordered nanoporous pattern [10].…”

Transparent conductor-embedding nanolens for Si solar cells

“…The previous researches suggest fundamental approaches for nanostructured solar cells. [1][2][3][4][5][6][7][8][9][10][11][12][13] Meanwhile, we can observe the limit in solar cell efficiencies. Additionally, a fancy concept has difficulty in the nanoscale fabrications and large-size applications.…”

“…This approach directly affects the efficiency of photo-generated carriers. [1][2][3][4][5][6] For an optically effective design, light-reflection at a solar cell surface holds fundamental effect. As the lightreflection decreases, solar cells can have more chances to absorb the incoming light into semiconductor materials.…”