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Title: Low-temperature high-mobility amorphous IZO for silicon heterojunction solar cells

Parasitic absorption in the transparent conductive oxide (TCO) front electrode is one of the limitations of silicon heterojunction (SHJ) solar cells efficiency. To avoid such absorption while retaining high conductivity, TCOs with high electron mobility are preferred over those with high carrier density. Here, we demonstrate improved SHJ solar cell efficiencies by applying high-mobility amorphous indium zinc oxide (a-IZO) as the front TCO. We sputtered a-IZO at low substrate temperature and low power density and investigated the optical and electrical properties, as well as subband tail formation-quantified by the Urbach energy (EU)-as a function of the sputtering oxygen partial pressure. We obtain an EU as low as 128 meV for films with the highest Hall mobility of 60 cm2/Vs. When comparing the performance of a-IZO films with indium tin oxide (ITO) and hydrogenated indium oxide (IO:H), we find that IO:H (115 cm2/Vs) exhibits a similar EU of 130 meV, while ITO (25 cm2/Vs) presents a much larger EU of up to 270 meV. The high film quality, indicated by the low EU, the high mobility, and low free carrier absorption of the developed a-IZO electrodes, result in a significant current improvement, achieving conversion efficiencies over 21.5%, outperforming those with standardmore » ITO.« less
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. École Polytechnique Fédérale de Lausanne (EPFL), Neuchatel (Switzerland)
  2. Institute of Physics ASCR, Prague (Czech Republic); Czech Technical Univ., Prague (Czech Republic)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 5; Journal Issue: 5; Journal ID: ISSN 2156-3381
Research Org:
École Polytechnique Fédérale de Lausanne (EPFL), Neuchatel (Switzerland)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
14 SOLAR ENERGY amorphous indium zinc oxide; electron mobility; heterojunction; indium tin oxide; silicon; solar cells; transparent conductive oxides; Urbach energy