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

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 similar to 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 (theta(in)) of 0-70 degrees, exhibiting a lower solar weighted reflectance (R-SW) value of similar to 7.1% at theta(in) = 0 degrees and a lower average RSW value of similar to 8.5% at theta(in) = 20-70 degrees than those (i.e., R-SW approximate to 10.1% at theta(in) = 0 degrees and average R-SW approximate to 15.6% at theta(in) = 20-70 degrees) 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 theta(in) = 20-70 degrees. Besides, the NHs PDMS exhibits a hydrophobic surface with a water contact angle of similar to 115 degrees.