Surface Micro/Nano-Textured Hybrid PEDOT:PSS-Silicon Photovoltaic Cells Employing Kirigami Graphene.

Kirigami graphene allows 2D material to transform into a 3D structure, which constitutes an effective transparent electrode candidate for photovoltaic cells having a surface texture. The surface texture of an inverted pyramid was fabricated on an Si substrate using photolithography and wet etching, followed by metal-assisted chemical etching to obtain silicon nanowires (SiNWs) on the surface of the inverted pyramid. Kirigami graphene with a cross-pattern array was prepared using photolithography and plasma etching on copper foil. Then, kirigami graphene was transferred onto hybrid heterojunction photovoltaic cells with poly(ethylene terephthalate)/silicone film. These cells consisted of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the p-type semiconductor, Si (100) as the inorganic n-type semiconductor, and a silver comb electrode on top of the PEDOT:PSS. The conductivity of the PEDOT:PSS was greatly improved. This improvement was significantly higher than that achieved by the continuous graphene sheet without a pattern. TEM and Raman results revealed that the greater improvement with kirigami graphene was due to the larger contact area between PEDOT:PSS and graphene. By using 2-layer graphene having a kirigami pattern, power conversion efficiency, under simulated AM1.5G illumination conditions, was significantly augmented by up to 9.8% (from 10.03% to 11.01%).