Substrate configuration, bifacial CdTe solar cells grown directly on transparent single wall carbon nanotube back contacts

• Published in: Solar energy materials and solar cells 2016-12, Vol.157 (C), p.35-41
• Main Authors: Khanal, Rajendra R., Phillips, Adam B., Song, Zhaoning, Xie, Yao, Mahabaduge, Hasitha P., Dorogi, Mark D., Zafar, Syed, Faykosh, Gary T., Heben, Michael J.
• Format: Article
• Language: English
• Subjects: CdTe solar cells; Cu-free; Substrate configuration; SWCNT; Tunnel contact
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.05.001

Substrate configuration CdTe/CdS solar cells were fabricated directly on 25nm thick single wall carbon nanotube (SWCNT) back contacts using a high temperature, commercial deposition process. No copper was introduced to facilitate the formation of an ohmic back contact at the back of the device. The champion device had an efficiency of 6.5%. The thin SWCNT layer allowed the device to be illuminated through the back contact, and a comparison of the device performance with front and backside illumination revealed several novel features of the SWCNT back contact. Our findings indicate that SWCNT films may be useful as a recombination layer contact for bifacial solar cells, photovoltaic windows, or two-terminal thin-film tandem solar cells. [Display omitted] •Bifacial CdTe device grown on SWCNT back contact in the substrate configuration using a large-scale manufacturing process.•Frontside illumination results in an efficiency of 6.5% even with rollover due to a current blocking TEC 15 M/SWCNT barrier.•Bifacial illumination eliminates rollover in J-V, and improves the efficiency of the device.•J-V and QE results indicate that a SWCNT layer can act as a recombination/tunnel junction contact.