Tantalum Nitride Electron Selective Contact for Crystalline Silicon Solar Cells

by Xinbo Yang, Erkan Aydin, Hang Xu, Jingxuan Kang, Mohamed Hedhili, Wenzhu Liu, Yimao Wan, Jun Peng, Christian Samundsett, Andres Cuevas, Stefaan De Wolf
Article Year: 2018

Bibliography

Yang, X., Aydin, E., Xu, H., Kang, J., Hedhili, M., Liu, W., ... & De Wolf, S. (2018). Tantalum Nitride Electron‐Selective Contact for Crystalline Silicon Solar Cells. Advanced Energy Materials, 1800608.

Extra Information

​​With this study, for the first time in literature Tantalum Nitride has been used as passivating contact on silicon solar cells.

Abstract

​​Minimizing carrier recombination at contact regions by using carrier‐selective contact materials, instead of heavily doping the silicon, has attracted considerable attention for high‐efficiency, low‐cost crystalline silicon (c‐Si) solar cells. A novel electron‐selective, passivating contact for c‐Si solar cells is presented. Tantalum nitride (TaNx) thin films deposited by atomic layer deposition are demonstrated to provide excellent electron‐transporting and hole‐blocking properties to the silicon surface, due to their small conduction band offset and large valence band offset. Thin TaNx interlayers provide moderate passivation of the silicon surfaces while simultaneously allowing a low contact resistivity to n‐type silicon. A power conversion efficiency (PCE) of over 20% is demonstrated with c‐Si solar cells featuring a simple full‐area electron‐selective TaNx contact, which significantly improves the fill factor and the open circuit voltage (Voc) and hence provides the higher PCE. The work opens up the possibility of using metal nitrides, instead of metal oxides, as carrier‐selective contacts or electron transport layers for photovoltaic devices.

Keywords

hole blocking Passivating contact silicon solar cell tantalum nitride