Effective Passivation of Large Area Black Silicon Solar Cells bySiO2/SiNx:H Stacks

Abstract

The performance of black silicon solar cells with various passivation films was characterized. Large area (156×156 mm2) black silicon was prepared by silver-nanoparticle-assisted etching on pyramidal silicon wafer. The conversion efficiency of black silicon solar cell without passivation is 13.8%. For the SiO2andSiNx:H passivation, the conversion efficiency of black silicon solar cells increases to 16.1% and 16.5%, respectively. Compared to the single film of surface passivation of black silicon solar cells, the SiO2/SiNx:H stacks exhibit the highest efficiency of 17.1%. The investigation of internal quantum efficiency (IQE) suggests that the SiO2/SiNx:H stacks films decrease the Auger recombination through reducing the surface doping concentration and surface state density of the Si/SiO2interface, andSiNx:H layer suppresses the Shockley-Read-Hall (SRH) recombination in the black silicon solar cell, which yields the best electrical performance of b-Si solar cells.

Black silicon: fabrication methods, properties and solar energy applications

“…Similarly, Zhao and co-workers found that their solar cell passivated by the stacked layer of SiO 2 /SiN x offers higher power conversion efficiency (17.1%), in comparison to those passivated either by SiO 2 (16.1%) or SiN x (16.5%) alone. 208 Interestingly, Zhao et al also noticed that thermal oxidation reduces emitter doping concentration, which is benecial for minimizing Auger recombination in an over-heavily doped emitter. 208 However, high temperature thermal oxidation is undesirable, especially for mc-Si solar cells.…”

“…208 Interestingly, Zhao et al also noticed that thermal oxidation reduces emitter doping concentration, which is benecial for minimizing Auger recombination in an over-heavily doped emitter. 208 However, high temperature thermal oxidation is undesirable, especially for mc-Si solar cells. Hsu et al adopted a trade-off strategy by performing a quick thermal anneal followed by PECVD SiN x growth on an n + -emitter.…”

Improvement of Conversion Efficiency of Silicon Solar Cells by Submicron‐Textured Rear Reflector Obtained by Metal‐Assisted Chemical Etching

“…By the SSCT treatment for 15 s, a ∼200 nm‐thick nanocrystalline Si layer with graded refractive index is formed on a Si surface, leading to an ultralow reflectance less than 3% in the wide wavelength region between 300 and 900 nm. However, the formation of the nanocrystalline Si layer greatly increases the surface area, similar to the case of other black Si structures such as nanocone, nanowire and porous Si, which increases surface recombination rates. In order to suppress the surface recombination rates, we have developed an effective passivation method for the nanocrystalline Si layer, i.e., phosphosilicate glass (PSG) deposition plus heat treatment, and the internal quantum efficiency for short‐wavelength light is greatly improved .…”

Surface nanocrystalline Si structure and its surface passivation for highly efficient black Si solar cells

“…Ultralow reflectivity Si surfaces called black Si have been produced by fabrication of nanostructures on Si surfaces, e.g., porous Si using electrochemical etching , stain etching , Si nanowire , etc. Deposition of metals such as silver (Ag) and platinum (Pt) on Si immersed in hydrogen peroxide (H 2 O 2 ) plus hydrofluoric acid (HF) solutions forms porous structure because metals greatly enhance Si dissolution resulting in cylindrical pores formed by movement of metals into Si, i.e., metal‐assisted chemical etching . Formation of the nanostructure can greatly decrease the reflectivity, but results in large surface area, leading to a high surface recombination rate.…”

“…Therefore, for achieving high conversion efficiency of solar cells, effective surface passivation methods should be performed on surface nanostructures. For porous structure produced by the metal‐assisted chemical etching, various methods for surface passivation including formation of a SiO 2 layer , deposition of a silicon nitride (SiN) layer , deposition of an Al 2 O 3 layer , and their combinations have been developed. Yang et al obtained the conversion efficiency of 18.8% by use of the SiN passivation method.…”