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 (θin) of 0-70°, exhibiting a lower solar weighted reflectance (RSW) value of ∼7.1% at θin = 0° and a lower average RSW value of ∼8.5% at θin = 20-70° than those (i.e., RSW ≈ 10.1% at θin = 0° and average RSW ≈ 15.6% at θin = 20-70°) of the FTO glass. In DSSC device applications, it increases the short-circuit current density (JSC) 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 θin = 20-70°. Besides, the NHs PDMS exhibits a hydrophobic surface with a water contact angle of ∼115°.