Investigation of the performance and stability of self-powered polythiophene-based photodiodes under UV and visible light illumination

Abstract

In this study, we fabricated polythiophene (PTh) and silver-decorated polythiophene (Ag@PTh) films on n-type silicon substrates using the electrochemical deposition method to investigate their electrical and photoelectrical properties in metal/interlayer/n-Si heterostructures under various conditions. The physical properties of the films were comprehensively investigated through UV-Vis, Raman, XPS and SEM analysis. The results from these analyses confirmed the successful deposition and formation of the films on the n-Si substrates. Additionally, a comparison of the current-voltage (I-V) characteristics of the PTh/n-Si and Ag@PTh/n-Si devices was conducted under both dark conditions and illumination with visible and UV light. While both devices exhibited typical rectifying diode behavior, the Ag@PTh/n-Si device demonstrated greater rectification with a RR of 2.49 x 105 at ± 2 V under dark conditions. In addition, the Ag@PTh/n-Si device, with self-powered property, displayed notably enhanced performance metrics, including a significantly higher ON/OFF ratio, responsivity, and detectivity, particularly evident under UV light illumination when compared to white light. Furthermore, to assess the long-term reliability of these devices, stability tests were conducted by repeating the I-V measurements after 90 days under identical conditions. The Ag@PTh/n-Si device exhibited considerably better stability over time than the PTh/n-Si device, maintaining consistent performance without notable degradation. So, in light of the findings, it can be concluded that the Ag@PTh/n-Si device has substantial potential for advancing optoelectronic technology.