Impedance Spectroscopy Analysis to Probe the Role of Interface Properties of Surface Micro-Engineered PEDOT:PSS/n-Si Solar Cells

Surface properties of silicon (Si) wafers play a critical role in the quality of polymer/Si interface and hence the photovoltaic (PV) performance of the PEDOT:PSS/n-Si hybrid solar cells (HSCs). In this study, the PEDOT:PSS/n-Si interface is thoroughly investigated for aqueous KOH micro-engineered Si surfaces (including the planar-Si surface as reference) based HSCs via electrochemical impedance spectroscopy (EIS), which has rarely been explored for such devices. Dynamic electrical parameters like, junction capacitance (CP), recombination resis-tance (RP), carrier lifetime (tau), built-in potential (Vbi), depletion region width (Wd) and Schottky barrier height (phi b) for the micro-engineered HSCs have been analyzed by EIS and co-related with the junction and PV per-formances. An optimized micro-engineered Si surface offered damage-free surface for the PEDOT:PSS/n-Si interface and resulted in high efficiency (11.82%) HSCs. A direct enhancement of the Rp by-5 fold, improved passivation near the interface (tau-234 mu s) and thus enhanced charge carrier collection probability for the champion textured cell as compared to planar one has been accounted to the enhanced performances. In addition, formation of an effective inversion layer in the n-Si at the PEDOT:PSS/n-Si interface has been confirmed by high Vbi: 0.691 eV and phi b: 0.937 eV in the optimal Si surfaces and hence efficient solar cell. The study may help to understand the PEDOT:PSS/n-Si interface on the micro-engineered Si surfaces and guide to design high efficiency HSCs technology.