Calcutta Institute of Engineering & Management

Few-layer transition metal dichalcogenides and perovskites are both promising materials in high-performance optoelectronic devices. Here, we developed a self-driven photodetector by creating a heterojunction between few-layer MoS₂ and lead-free perovskite Cs₂CuBr₄. The detector shows a unique property of very high sensitivity in a broad spectral range of 400 to 800 nm with response speed in a millisecond order. Current-voltage characteristics of the heterojunction device show rectifying behavior, in contrast to the ohmic behavior of the MoS₂-based device. The rectifying behavior is attributed to the type II band alignment of the MoS₂/Cs₂CuBr₄ heterojunction. The device shows a broadband (400 to 800 nm) photodetection with very high responsivity reaching up to 2.8 × 10⁴ A/W and detectivity of 1.6 × 10¹¹ Jones at a bias voltage of 3 V. The detector can also operate in self-bias mode with sufficient response. The photocurrent, photoresponsivity, detectivity, and external quantum efficiency of the device are found to be dependent on the illumination power density. The response time of the device is found to be ∼32 and ∼79 ms during the rise and fall of the photocurrent. The work proposes a MoS₂/Cs₂CuBr₄ heterostructure to be a promising candidate for cost-effective, high-performance photodetector.

The online version contains supplementary material available at 10.1007/s00354-021-00143-1.

The novel coronavirus disease 2019 (COVID-19) emerged in Wuhan, China, and has spread rapidly to nearly every part of the world.Unfortunately, no drug or vaccine has been accepted for the treatment of this pandemic.Researchers have established the efficacy of some existing antiviral drugs to control COVID-19 in vitro.Some of them are remdesivir (GS-5734), chloroquine, hydroxychloroquine, theaflavin.Topol. indexes are math. interpretations of a mol. generated by an algorithm implemented to a given mol. representation.Topol. indexes are used to model different physicochem. properties and biol. activities of chem. compoundsIn this work, some degree-based and neighborhood degree sum-based topol. indexes are investigated for the aforesaid antiviral drugs using polynomial approach.The results obtained can aid in the design of new medicine for the treatment of COVID-19.