High-specific-power flexible transition metal dichalcogenide solar cells

Koosha Nassiri Nazif; Alwin Daus; Jiho Hong; Nayeun Lee; Sam Vaziri; Aravindh Kumar; Frederick Nitta; Michelle E Chen; Siavash Kananian; Raisul Islam; Kwan-Ho Kim; Jin-Hong Park; Ada S Y Poon; Mark L Brongersma; Eric Pop; Krishna C Saraswat

doi:10.1038/s41467-021-27195-7

High-specific-power flexible transition metal dichalcogenide solar cells

Nat Commun. 2021 Dec 9;12(1):7034. doi: 10.1038/s41467-021-27195-7.

Authors

Koosha Nassiri Nazif^#¹, Alwin Daus^#¹, Jiho Hong^{2

3}, Nayeun Lee^{2

3}, Sam Vaziri¹, Aravindh Kumar¹, Frederick Nitta¹, Michelle E Chen³, Siavash Kananian¹, Raisul Islam¹, Kwan-Ho Kim^{4

5}, Jin-Hong Park^{4

6}, Ada S Y Poon¹, Mark L Brongersma^{2

3

7}, Eric Pop^{1

3}, Krishna C Saraswat^{8

9}

Affiliations

¹ Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA.
² Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
³ Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.
⁴ Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon, 16419, Korea.
⁵ Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
⁶ SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, Korea.
⁷ Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
⁸ Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA. saraswat@stanford.edu.
⁹ Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA. saraswat@stanford.edu.

^# Contributed equally.

Abstract

Semiconducting transition metal dichalcogenides (TMDs) are promising for flexible high-specific-power photovoltaics due to their ultrahigh optical absorption coefficients, desirable band gaps and self-passivated surfaces. However, challenges such as Fermi-level pinning at the metal contact-TMD interface and the inapplicability of traditional doping schemes have prevented most TMD solar cells from exceeding 2% power conversion efficiency (PCE). In addition, fabrication on flexible substrates tends to contaminate or damage TMD interfaces, further reducing performance. Here, we address these fundamental issues by employing: (1) transparent graphene contacts to mitigate Fermi-level pinning, (2) MoO_x capping for doping, passivation and anti-reflection, and (3) a clean, non-damaging direct transfer method to realize devices on lightweight flexible polyimide substrates. These lead to record PCE of 5.1% and record specific power of 4.4 W g^-1 for flexible TMD (WSe₂) solar cells, the latter on par with prevailing thin-film solar technologies cadmium telluride, copper indium gallium selenide, amorphous silicon and III-Vs. We further project that TMD solar cells could achieve specific power up to 46 W g^-1, creating unprecedented opportunities in a broad range of industries from aerospace to wearable and implantable electronics.

Abstract

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