Pyroelectricity-enhanced lateral photovoltaics in pyramid-structured Si/PEDOT:PSS heterojunction for multifunctional imaging

Herein, a series of pyramid-structured Si/PEDOT:PSS heterojunctions was successfully fabricated with etching times ranging from 0 to 40 minutes, and their lateral photovoltaic effects (LPEs) were systematically investigated. The results reveal that the LPE response is strongly dependent on the etching duration of the pyramid texture, with the device etched for 30 minutes achieving a maximum position sensitivity of 632.1 mV/mm and a minimum nonlinearity of only 1.87%. This performance enhancement stems from the enlarged built-in field, optimized carrier diffusion paths, and improved light absorption. More importantly, a pyroelectric effect arising from the polar interface was observed. The induced pyroelectric field effectively couples with the intrinsic built-in field, facilitating efficient separation of photoexcited carriers and resulting in a significantly increased position sensitivity of 1221.8 mV/mm, demonstrating an improvement of 193.2%, and a rapid response time of 0.15/0.15 ms. Furthermore, the LPE remains effective over a wide electrode spacing range from 0.4 to 3.8 mm. Although the LPE response decreases with expanding spacing, a notable position sensitivity of 186.4 mV/mm is still achieved at a spacing of 3.8 mm. Based on the distinct wavelength dependence of the LPE response and its pyroelectric improvement, a wavelength-resolved optical imaging system was further demonstrated. In addition, the imaging intensity can be tuned by adjusting the electrode spacing, highlighting the unique versatility of LPE-based devices.