Admittance spectroscopy of organic-silicon heterojunction structures fabricated with ultrasound assistance

The development of methods for controlled modification of silicon–polymer structures is essential for advancing next-generation solar cells. This study investigates the influence of ultrasound treatment (UST) applied during fabrication on the electrical properties of Ag/PEDOT:PSS/n-Si/Zn-Ga heterostructures. The analysis combines complementary approaches based on current–voltage and capacitance–voltage measurements, as well as admittance and impedance spectroscopy. UST was found to narrow the defect energy spectrum in the interface region by restructuring unstable trap configurations and to accelerate aging processes, which are important for the long-term stability of system parameters. Quantitative characteristics of acoustically induced variations in parameters associated with both transport and relaxation processes, including characteristic times, current densities, dispersion parameters, and ideality factors, are presented. The results suggest that longitudinal vibrations primarily promote polymer phase separation, whereas radial vibrations seem to be predominantly linked to film homogenization and PEDOT molecular reorientation. It is demonstrated that ultrasound is an effective tool for controlled engineering of the properties of organic–inorganic electronic devices.