Nanostructured encapsulation coverglasses with wide-angle broadband antireflection and self-cleaning properties for III–V multi-junction solar cell applications

• Nanocone arrays (NCAs) are fabricated as an antireflection coating (ARC) of the encapsulation coverglass by dry etching using glancing angle deposited gold nanopatterns without additional thermal treatments.
• The NCAs ARC coverglass exhibits a superhydrophilic surface and high transmission properties in wide ranges of wavelength and incident light angle.
• For the encapsulated III–V InGaP/GaAs/Ge triple-junction solar cell with the NCAs ARC coverglass, the higher solar power conversion is obtained compared to the encapsulated cell with a bare coverglass.
• The NCAs ARC coverglass is very promising for high-performance photovoltaic systems.

We report the effect of nanocone arrays (NCAs) as an antireflection coating (ARC) of encapsulation coverglasses on the device performance of encapsulated III–V InGaP/GaAs/Ge triple-junction (TJ) solar cells. The NCAs were fabricated on the single-side surface of glasses using the gold nanopatterns (i.e., nanoclusters) prepared by the glancing angle deposition technique without additional thermal treatment and the subsequent dry etching. Their wetting behavior and optical properties, together with a theoretical prediction using the rigorous coupled-wave analysis method, were investigated. The NCAs ARC coverglass exhibited a much lower water contact angle (θCA) of <5° (i.e., superhydrophilic surface) and higher solar weighted transmittance (SWT) of ~95.9% over a wide wavelength region of 300–1800 nm at normal incidence compared to the bare coverglass (i.e., θCA~63° and SWT ~92.8%). The use of the NCAs ARC coverglass in encapsulated III–V InGaP/GaAs/Ge TJ solar cells led to the higher short circuit current density (Jsc) of 14.22 mA/cm2 and thus improved the conversion efficiency (η) to 32.07% (cf., Jsc=13.84 mA/cm2 and η=30.6% for the cell with the bare coverglass). For incident angle-dependent solar cell characteristics, it also showed a superior solar power conversion property in wide incident light angles of 20–80°.

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