Using hydrogen-doped In2O3 films as a transparent back contact in (Ag,Cu)(In,Ga)Se-2 solar cells

作者：Keller Jan^*; Nilsson Nina Shariati; Aijaz Asim; Riekehr Lars; Kubart Tomas; Edoff Marika; Torndahl Tobias

来源：Progress in Photovoltaics: Research and Applications , 2018, 26(3): 159-170.

DOI：10.1002/pip.2977

• ACIGS
• bifacial solar cell
• In2O3
• IOH
• transparent back contact

This study evaluates the potential of hydrogen-doped In2O3 (IOH) as a transparent back contact material in (Ag-y,Cu1-y)(In1-x,Ga-x)Se-2 solar cells. It is found that the presence of Na promotes the creation of Ga2O3 at the back contact during (Ag-y,Cu1-y)(In1-x,Ga-x)Se-2 growth. An excessive Ga2O3 formation results in a Ga depletion, which extends deep into the absorber layer. Consequently, the beneficial back surface field is removed and a detrimental reversed electrical field establishes. However, for more moderate Ga2O3 amounts (obtained with reduced Na supply), the back surface field can be preserved. Characterization of corresponding solar cells suggests the presence of an ohmic back contact, even at absorber deposition temperatures of 550 degrees C. The best solar cell with an IOH back contact shows a fill factor of 74% and an efficiency (eta) of 16.1% (without antireflection coating). The results indicate that Ga2O3 does not necessarily act as a transport barrier in the investigated system. Observed losses in open circuit voltage (V-OC) as compared to reference samples with a Mo back contact are ascribed to a lower Na concentration in the absorber layer.

• 出版日期2018-3