## 4 Conclusions  
MoS\({}_{2}\) nanostructures were grown directly on cellulose paper substrates using the microwave-assisted hydrothermal synthesis method with different temperatures and synthesis times. Variations were observed in the amount of MoS\({}_{2}\) grown on top of cellulose fibers as a function of the synthesis parameters. The analysis also showed the distribution of the metallic and semiconductor phases of the MoS\({}_{2}\) nanostructures throughout the sample, generating metal/semiconductor interfaces. Near-infrared sensors were produced from the synthesized samples, where the screen-printing technique was used to deposit interdigital Ag NPs contacts in the samples. The results of the electrical characterizations showed an improvement in the performance of the sensor with the increase in nanostructures synthesis time, for the three temperatures of synthesis used. Such results can be explained by the increase in the amount of MoS\({}_{2}\), according to the model created for the  
Figure 7: **(a)** Current dependence due to the decrease in the power of the light source (laser 980 nm, ON, OFF) on the sensor. The inset shows the relationship between the generated photocurrent and the irradiation power of the light source on the sensor for the synthesized sample at 200 \({}^{\circ}\)C for 120 min. The bias voltage used here was 4 V. **(b)** Responsivity, Specific Detectivity, and EQE (inset) under different irradiation powers of the device regarding the synthesized sample with a temperature of 200 \({}^{\circ}\)C and a time of 120 min. sensors operation. Based on the data analysis, the photodetector produced from the sample synthesized at 200 \({}^{\circ}\)C and 120 min presented a high responsivity value (290 mA/W), a specific detectivity value (1.8 \(\times\) 10\({}^{9}\) Jones) and an external quantum efficiency of 37%, with response times \(\tau_{\rm rise}\) = 3.7 s and \(\tau_{\rm decay}\) = 4.7 s. The sensors produced from the samples synthesized at a temperature of 220 \({}^{\circ}\)C also showed high values of responsivity, however, the high temperature causes substrate degradation, making the device fragile and the application difficult. The improvement in the responsivity value of the photodetector can be associated with the photoconductive effect due to three probably factors: (i) the high concentration of the metallic 1T phase in MoS\({}_{2}\) layers; (ii) trap states in the MoS\({}_{2}\) and/or paper/MoS\({}_{2}\) interface; and (iii) hot electron injection from surface plasmon resonance in the Ag NPs electrodes to MoS\({}_{2}\) nanomaterial. An analysis of the photocurrent dependence as a function of the incident radiation power on the sensor showed a linear dependence of the device's photocurrent in relation to the power of the light source. The responsivity showed a great increase with the reduction of the irradiation power, at the value of 290 mA/W for the power of 2 mW. This result must be associated with the increase in the probability of recombination with the increase in the photoexcited carriers. This work provides a functional example, as well as a promising strategy, to improve the performance of 1T/2H MoS\({}_{2}\)-based photodetectors. Further studies on the surface state passivation for device optimization, for example, will be conducted to improve photocurrent in MoS\({}_{2}\) photodetector synthesized by the microwave-assisted hydrothermal synthesis method. The following are available online at [[https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)]([https://www.mdpi.com/2076-341](https://www.mdpi.com/2076-341)) 7/11/3/1234/s1, Figure S1: SEM images of the MoS2 nanostructures grown directly on cellulose paper substrates with different temperature and time of synthesis, Figure S2: Micro-Raman mapping and detachment of phases 1T (blue) and 2H (green) in samples of MoS2 nanostructures grown directly on paper substrates with different temperature and time of synthesis, Figure S3: Absorbance spectrum of silver nanoparticles ink in an isopropyl alcohol solution.