Improving the performance of the self-powered polymer-based UV/Vis photodetectors via carbon fibers

Both Polyvinylpyrrolidone (PVP) and matrix-polymer of carbon (C)-PVP fibers (Fs) composites were synthesized by using the electrospinning technique and deposited onto the p-Si wafers to obtain PVP Fs/p-Si and C-PVP Fs/p-Si devices. The ultraviolet/Visible (UV/Vis) photodetector performance of both devices was compared. Both devices gave self-powered mode and with increasing the visible light intensity, the photocurrents of both devices increased. Besides, it was observed that the optical performance of the device containing C was better than the PVP Fs/p-Si device in both visible and UV lights. This was attributed to the high absorption properties of carbon and the increase in conductivity in the PVP due to carbon fibers. Furthermore, it is thought that the electric field formed in the carbon-PVP interaction and C-PVP/p-Si interface improves the optical properties of the device by increasing the exciton separation efficiency. Under the self-powered mode, the C-PVP Fs/p-Si device exhibited a maximum detectivity and ON/OFF ratio of 5.60 × 1010 Jones and 53 764, respectively for UV light of 365 nm. Under 100 mW visible light, these values were determined as 1.01 × 1010 Jones and 9739, respectively, at V = 0. In addition, from the obtained noise-equivalent power (NEP) values, it was concluded that weaker signals can be detected under UV light (6.94 × 10−14 w Hz−1/2, at −2 V) than visible light (3.32 × 10−13 w/Hz1/2, at −2 V) for C-PVP Fs/p-Si.