This report demonstrates the fabrication of all MoS₂ based 2D/0D unipolar heterojunctions using a simple one pot hydrothermal process and their utilization in a flexible broadband photodetector covering the spectral range from the ultraviolet to the near infrared region. The discontinuous deposition of 0D MoS₂, which has absorbance in the UV region, on 2D MoS₂, having absorbance in the visible and near-infrared (NIR) regions, enables broadband detection. Further, contact engineering was performed wherein both the metal contacts were fabricated on 2D MoS₂, thereby enabling the effective capture of photogenerated carriers. Also, a unipolar junction formed due to the Fermi level difference between 2D and 0D MoS₂ produces a localized electric field that helps in the efficacious separation of photogenerated electron–hole pairs. The responsivity values of the fabricated photodetector were calculated to be 7.56 mA W⁻¹, 12.8 mA W⁻¹, and 3.95 mA W⁻¹ in the UV, visible and NIR regions, respectively, indicating that the fabricated device is more sensitive towards the visible region. A detailed understanding of the photodetection mechanism of this unique heterostructure is presented using bandgap theory and trap states. The successful demonstration of such a cost-effective, scalable 2D/0D based broadband photodetector should lead to potential applications in optoelectronics, security, and wearable electronics.

The monitoring of respiratory disorders requires breath sensors that are fast, robust, and convenient to use and can function under real time conditions. A MOF based flexible sensor is reported for the first time for breath sensing applications. The properties of a highly porous HKUST-1 MOF and a conducting MoS₂ material have been combined to fabricate an electronic sensor on a flexible paper support for studying sleep apnea problems. Extensive breath sensing experiments have been performed and interestingly the fabricated sensor is efficient in detecting various kinds of breaths such as deep, fast, slow and hydrated breath. The MOF breath sensor shows a fast response time of just ∼0.38 s and excellent stability with no decline in its performance even after a month. A plausible mechanism has been proposed and a smartphone based prototype has been prepared to demonstrate the real time applications of the hybrid device. This work demonstrates great potential for the application of MOFs in healthcare with a special focus on breath sensing and sleep apnea diagnosis.