development of flexible electronics, especially in the biomedical field, which has led to an exploration of flexible substrate photodetectors. [7,8] These devices are far more compact and cost-effective compared to the conventional bulk substrate devices and reduce the expenditure on material as well as fabrication. [9] Still, several issues need to be addressed. [10] Some of the issues are surface roughness, thermal stability, and cleanroom compatibility. Almost all of the flexible substrates utilized (polymers, paper, textile, etc.) have a rough surface which not only affects the charge carrier mobility but also increases the recombination rate. Further, the rise time is also affected which affects the gain of the photodetector. The second is thermal stability, that is, most of the flexible substrates cannot withstand high temperatures, and hence performing high-temperature processes is not possible which restricts limited fabrication methodologies. [11] Last, the flexible substrates are not cleanroom compatible and novel methodologies need to be developed for integrating novel functional nanomaterials onto the flexible substrates. Novel functional materials ranging from 0D to 2D, and hybrids (0D-1D, 0D-2D, and 1D-2D) based on these materials have been explored for this purpose. [12-15] Piezotronics is another means to improve the responsivity upon application of external strain which modulates the depletion region width and increases the electric field and thereby the responsivity. But the issue with piezotronics is that, the application of strain leads to permanent damage in the device, thereby decreasing the reliability of the photodetector. Localized surface plasmon resonance (LSPR) is another means of increasing the absorption, and hence the responsivity and speed, and is a widely researched domain for conventional rigid substrate devices with the decoration of noble nanoparticles (NPs). [16-19] However, reports on the use of metal NPs for high-performance flexible devices using LPSR are few. Moreover, the reports on the comparative performance of different NPs also remain limited. Hence, there is a need to explore Plasmonic enhancement in flexible substrate devices. Transition metal dichalcogenides (TMDs) are a popular class of 2D materials because of their outstanding optical and mechanical properties and tunable bandgap. [20] Of these, MoS 2 is of special interest due to its superior electrical properties, high Even though there are reports on flexible photodetectors, one of the main issues that still needs to be resolved is the lower values of responsivity arising due to the use of non-conventional substrates such as polymers, cellulose paper, etc. There are ways to improve the responsivity, such as piezotronics and surface plasmonic resonance, but studies on utilizing the same for flexible substrates remain limited. Further, the comparative performance of different nanoparticles (NPs) remains unexplored. This report demonstrates the fabrication of flexible visible/near-infrared (NIR) photodetectors by...

No abstract

Even though there are various reports on the fabrication of flexible photodetectors, still there is a need for the development of high-performance photodetectors. In recent years, the plasmonic photodetection technique has emerged as one of the prominent solutions to enhance photodetection performance. In this work, a flexible and high-performance broadband (visible-near-infrared (NIR)) plasmonic photodetector is demonstrated by integrating gold (Au) nanoparticles (NPs) on two-dimensional (2D) ReS2 nanosheets. Fabricated Au-NPs/ReS2 showed an approximately 15-fold enhancement in the photodetection performance compared to pristine ReS2. Photoresponsivity of the fabricated Au-NPs/ReS2 device in visible (Vis) and NIR regions is ∼2.1 and ∼1.3 A W–1, respectively. Significant enhancement in the photosensing performance of the device could be a combined effect of multiple factors, including localized surface plasmon resonance and effective charge transfer at the interface of Au-NPs and ReS2. The response speed of the fabricated device is approximately 200 ms. Furthermore, theoretical understanding of light interaction with Au-NPs is studied, and also electromagnetic simulations are performed using Lumerical Finite Difference Time Domain Multiphysics simulation to investigate the plasmon coupling effect of Au-NPs on 2D ReS2 nanosheets. To further understand the photodetection mechanism, the energy band diagram of the Au-NPs/ReS2 interface is drawn using ultraviolet photoelectron spectroscopy measurements.