Solar power generation enhancement of dye-sensitized solar cells using hydrophobic and antireflective polymers with nanoholes

Abstract

We improve the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) using polydimethylsiloxane (PDMS) patterned with negatively tapered nanoholes (NHs) as a protective antireflection layer of the external glass surface. The NHs PDMS layers are prepared by a soft lithography via silicon molds with conical nanopillars. The NHs PDMS with a NH depth of ∼320 nm decreases the surface reflection of fluorine doped tin oxide (FTO)-coated glass over a wide wavelength range of 350–800 nm at incident angles (θ_in) of 0–70°, exhibiting a lower solar weighted reflectance (R_SW) value of ∼7.1% at θ_in = 0° and a lower average R_SW value of ∼8.5% at θ_in = 20–70° than those (i.e., R_SW ≈ 10.1% at θ_in = 0° and average R_SW ≈ 15.6% at θ_in = 20–70°) of the FTO glass. In DSSC device applications, it increases the short-circuit current density (J_SC) from 15.69 to 16.52 mA cm⁻², thus resulting in an enhanced PCE value of 7.56% compared to the reference DSSC (i.e., PCE = 7.15%). For different NH depths, the optical reflectance characteristics of the NHs PDMS/FTO glass are theoretically investigated using a rigorous coupled-wave analysis method, showing similar trends between the calculated and measured results. For solar spectrum angle-dependent photocurrents, it also shows a remarkable device performance at θ_in = 20–70°. Besides, the NHs PDMS exhibits a hydrophobic surface with a water contact angle of ∼115°.