Abstract
Hybrid crystalline silicon (c-Si) solar cells incorporating PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) as a hole-selective contact offer a promising alternative to conventional doped silicon solar cells, enabling non-toxic doping, low-temperature, and vacuum-free processing. However, achieving uniform coverage and optimal film morphology remains challenging due to the inherent hydrophobicity of crystalline silicon, which hinders the wetting of aqueous PEDOT:PSS dispersions. Conventional fluorinated surfactants, commonly used to enhance PEDOT:PSS wetting, pose environmental and health risks due to their bioaccumulation and persistence. This study explores xanthan gum (XG), a biodegradable and non-toxic polysaccharide, as a green alternative for modifying the rheological properties of PEDOT:PSS and improving its deposition on hydrophobic silicon surfaces. The impact of XG on film morphology, thickness control, and adhesion was evaluated using atomic force microscopy (AFM) and profilometry. PEDOT:PSS-XG composite films were deposited via spin-coating and treated with the secondary dopants dimethyl sulfoxide (DMSO) and isopropyl alcohol (IPA) to assess their effect on sheet resistance and optical properties. Fourier-transform infrared (FTIR) and Raman spectroscopy confirmed that XG does not chemically alter PEDOT:PSS but influences its molecular organization and surface distribution. These results highlight the role of XG and the underlying physical mechanisms involved in film formation, interfacial adhesion, and morphological stabilization. Textured hybrid c-Si solar cells fabricated with PEDOT:PSS-XG films achieved a power conversion efficiency (PCE) of up to 6.6% when combined with secondary doping. These results highlight XG as a sustainable alternative to fluorinated surfactants, facilitating scalable, eco-friendly processing for next-generation hybrid photovoltaics.