Optical Anisotropy and Compositional Ratio of Conductive Polymer PEDOT:PSS and Their Effect on Photovoltaic Performance of Crystalline Silicon/Organic Heterojunction Solar Cells

We demonstrate the optical anisotropy of a transparent conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance of n-type crystalline silicon (n-Si)/PEDOT:PSS heterojunction solar cells. The depth profile of PEDOT/PSS compositional ratio and optical anisotropy depends on the type of polar solvent and/or external DC bias supplied to n-Si substrate during film deposition by spin coating (SC) and chemical mist deposition (CMD). N-Si/PEDOT:PSS heterojunction solar cells with higher PEDOT/PSS compositional ratio near the film surface exhibited better power conversion efficiency η of 12.5% (@2 × 2 cm2) without any light harvesting techniques. In this chapter, the correlation among the optical anisotropy, the depth profile of PEDOT/PSS compositional ratio in conductive polymer PEDOT:PSS, and the photovoltaic performance of n-Si/PEDOT:PSS heterojunction solar cells is demonstrated.