Title
Surface nanocrystalline Si structure and its surface passivation for highly efficient black Si solar cells
Author
Kentaro Imamura, Daichi Irishika, Hikaru Kobayashi
Year
2017
Journal
Progress in Photovoltaics: Research and Applications
Abstract
19.5% conversion efficiency crystalline silicon (Si) solar cells having simple structure without antireflection coating have been fabricated using the surface structure chemical transfer method which produces a nanocrystalline Si layer simply by contacting catalytic platinum with Si wafers in hydrogen peroxide plus hydrofluoric acid solutions. The reflectivity becomes less than 3% after the surface structure chemical transfer method due to formation of black Si. Deposition of phosphosilicate glass and heat treatment at 925 °C performed for formation of pn-junction effectively passivate the nanocrystalline Si surface. With this phosphosilicate glass passivation plus the hydrogen treatment at 400 °C, the internal quantum efficiency is greatly improved and reaches 81% at a wavelength of 400 nm. Analysis of ellipsometry data shows that incident light with wavelength shorter than 400 nm is almost completely absorbed by the nanocrystalline Si layer. The high internal quantum efficiency for short wavelength light is attributed to effective surface passivation and the nanocrystalline Si layer band-gap energy which decreases with the distance from the top of the network structure of the nanocrystalline Si layer.
Instrument
FP-8600
Keywords
Fluorescence, Photoluminescence, Nanostructures, Materials