Double-Layered PEDOT:PSS Films Inducing Strong Inversion Layers in Organic/Silicon Hybrid Heterojunction Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Si hybrid heterojunction solar cells (HHSCs) have attracted wide interests due to the potential high efficiency and low cost, but their open circuit voltage is limited. Here, double-layered PEDOT:PSS films (DL-PEDOT:PSS), high-work-function AI4083-type PEDOT:PSS (HW-PEDOT:PSS) used to combine with high-conductivity PH1000-type PEDOT:PSS (HC-PEDOT:PSS), were applied to induce strong inversion layers at the n-type silicon surface in PEDOT:PSS/Si HHSCs resulting in a quasi-p–n junction. Capacitance–voltage and minority carrier lifetime mapping demonstrates that the quasi-p–n junction was formed by strong inversion effect with large built-in voltage. The device with DL-PEDOT:PSS with 7 wt % EG added in HW-PEDOT:PSS (EG7-DL-PEDOT:PSS) exhibits a large open circuit voltage of 640 mV without any other modification, fill factor of 0.755, and power conversion efficiency of 12.69%. This suggests a promising method for the fabrication of low-cost and high-performance PEDOT:PSS/Si HHSCs, as well as a p-type passivated contact in the next-generation solar cells.