Efficiency Enhancement of Organic Solar Cells Using Hydrophobic Antireflective Inverted Moth-Eye Nanopatterned PDMS Films

Poly-dimethylsiloxane (PDMS) films with 2D periodic inverted moth-eye nanopatterns on one surface are implemented as antireflection (AR) layers on a glass substrate for efficient light capture in encapsulated organic solar cells (OSCs). The inverted moth-eye nanopatterned PDMS (IMN PDMS) films are fabricated by a soft imprint lithographic method using conical subwavelength grating patterns formed by laser interference lithography/dry etching. Their optical characteristics, together with theoretical analysis using rigorous coupled-wave analysis simulation, and wetting behaviors are investigated. For a period of 380 nm, IMN PDMS films laminated on glass substrates exhibit a hydrophobic surface with a water contact angle (theta(CA)) of approximate to 120 degrees and solar weighted transmittance (SWT) of approximate to 94.2%, both significantly higher than those (theta(CA)approximate to 36 degrees and SWT approximate to 90.3%) of bare glass substrates. By employing IMN PDMS films with a period of 380 nm on glass substrates for OSCs, an enhanced power conversion efficiency (PCE) of 6.19% is obtained mainly due to the increased short-circuit current density (J(sc)) of 19.74 mA cm(-2) compared to the OSCs with the bare glass substrates (PCE = 5.16% and J(sc) = 17.25 mA cm(-2)). For the OSCs, the device stability is also studied.