Charge Carrier Transport, Trapping, and Recombination in PEDOT:PSS/n-Si Solar Cells

The effect of interface states on electrical transport mechanisms in PEDOT:PSS/n-Si solar cells (SCs) was investigated by using admittance spectroscopy as well as current–voltage (J–V) and capacitance–voltage (C–V) measurements. The J–V dependences measured in the temperature range of 80–300 K can be described by an equivalent circuit for a two-diode model including parallel and serial resistances. From the analysis of the temperature dependence of the J–V curves, the role of the silicon oxide layer in charge carrier transport in the hybrid solar cell (SC) was clarified. A density of states of 2.5 × 1010 cm–2 eV–1 localized at the SiO2/Si interface at Ev + 0.3 eV is deduced from admittance measurements. The low density of electrically active defects near the Fermi level and an interface recombination rate of 480 cm/s indicate a good passivation of the PEDOT:PSS/n-Si interface. The interfacial defects associated with dangling bonds (Pb centers) at the polymer–silicon interface are responsible for an increase of the series resistances and the dominance of the recombination current at forward biases.