Doping and Polar Interface-Induced High-Position Sensing in the PEDOT:PSS/Si Heterojunction and Its Multifunctional Optical Imaging

A highly sensitive, self-powered position-sensitive detector (PSD) based on a PEDOT:PSS/Si heterojunction is prepared. Band structure optimization via FS-300 additive doping significantly enhances the built-in electric field, achieving a maximum open-circuit voltage of 0.45 V (0.25 V for the undoped device) and a position sensitivity of 404.6 mV/mm (225.3 mV/mm for the undoped device). Remarkably, polar symmetry at the PEDOT:PSS/Si interface induces a pyroelectric field under pulsed light illumination, which dramatically boosts the position sensitivity to 778.8 mV/mm, representing an enhancement of 192.5%. Leveraging these properties, we designed an imaging system that exploits the distinct lateral photovoltaic responses and pyroelectric enhancements for different laser wavelengths to achieve high-resolution optical imaging. Furthermore, the PSD maintains a robust lateral photovoltaic response across electrode spacings from 0.5 to 9 mm, retaining a position sensitivity of 170 mV/mm even at a 9 mm spacing. This tunable performance across electrode spacings allows for adjustable imaging resolution, highlighting the device's versatility for advanced optoelectronic applications.