Ultrathin Ta2O5 electron-selective contacts for high efficiency InP solar cells

Parvathala Reddy Narangari, Siva Krishna Karuturi, Yiliang Wu, Jennifer Wong-Leung, Kaushal Vora, Mykhaylo Lysevych, Yimao Wan, Hark Hoe Tan, Chennupati Jagadish, Sudha Mokkapati

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Heterojunction solar cells with transition-metal-oxide-based carrier-selective contacts have been gaining considerable research interest owing to their amenability to low-cost fabrication methods and elimination of parasitic absorption and complex semiconductor doping process. In this work, we propose tantalum oxide (Ta2O5) as a novel electron-selective contact layer for photo-generated carrier separation in InP solar cells. We confirm the electron-selective properties of Ta2O5 by investigating band energetics at the InP-Ta2O5 interface using X-ray photoelectron spectroscopy. Time-resolved photoluminescence and power dependent photoluminescence reveal that the T2O5 inter-layer also mitigates parasitic recombination at the InP/transparent conducting oxide interface. With an 8 nm Ta2O5 layer deposited using an atomic layer deposition (ALD) system, we demonstrate a planar InP solar cell with an open circuit voltage, Voc, of 822 mV, a short circuit current density, Jsc,of 30.1 mA cm-2, and a fill factor of 0.77, resulting in an overall device efficiency of 19.1%. The Voc is the highest reported value to date for an InP heterojunction solar cells with carrier-selective contacts. The proposed Ta2O5 material may be of interest not only for other solar cell architectures including perovskite cells and organic solar cells, but also across a wide range of optoelectronics applications including solid state emitting devices, photonic crystals, planar light wave circuits etc.

Original languageEnglish
Pages (from-to)7497-7505
Number of pages9
Issue number15
Publication statusPublished - 28 Mar 2019

Cite this

Narangari, P. R., Karuturi, S. K., Wu, Y., Wong-Leung, J., Vora, K., Lysevych, M., Wan, Y., Tan, H. H., Jagadish, C., & Mokkapati, S. (2019). Ultrathin Ta2O5 electron-selective contacts for high efficiency InP solar cells. Nanoscale, 11(15), 7497-7505. https://doi.org/10.1039/c8nr09932d