Absorption enhancement of ZnPc thin films grown on nano-patterned polymer underlayer

We developed a simple and efficient nanoimprinting technique based on the capillary force lithography to fabricate two-dimensional arrays of nanoholes on the surface of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layers. A replicated polymer mold was used as the imprinting stamp, and the surface nanopatterns were formed by capillary rise of the moist PEDOT:PSS solution. The nanopatterned PEDOT:PSS layer could refract the incident light, thereby increasing the path lengths of the light passing through the zinc phthalocyanine (ZnPc) films deposited on the PEDOT:PSS layer. As a result, the absorbance of the ZnPc films was enhanced by up to ∼14% in parts of the absorbance range of ZnPc.