Highly Air-Stable and Sensitive Self-Powered Broadband Photodetector Based on a PVA–MoS 2 Fibers/n-Si Heterojunction

We designed and demonstrated a self-powered poly(vinyl alcohol) (PVA)–MoS 2 fibers/n-Si heterojunction (HJ) device for a high-performance photodetector. Light-intensity-dependent I – V measurements were carried out, ranging from the dark to 150 mW/cm 2 for visible light. Furthermore, electro-optical measurements of HJ under UV (365 and 395 nm), IR (850 nm), and yellow light (590 nm) for constant light power were investigated in detail with the help of I – V characteristics. The PVA–MoS 2 /n-Si device showed a pronounced photoresponse at all of these wavelengths. The optimum values of the wavelength-dependent photodetector parameters were obtained under yellow light. In the evaluation of the optical measurements under yellow light, the maximum on/off ratio, R, D, NPDR, and EQE values were 2.91 × 10 5 (zero bias), ∼480 mA/W ( V = −2.0 V), 5.71 × 10 12 Jones (zero bias), 4.64 × 10 9 W 1– (zero bias), and 100.8 ( V = −2.0 V), respectively. Furthermore, after 25 and 125 days without any encapsulation, the air stability of the device was observed to be excellent in the dark and the light.