Pyrene-functionalized tungsten disulfide as stable resistive photosensor

Abstract

Pyrene carrying an 1,2-dithiolane linker was employed to functionalize exfoliated WS₂ and the resulting material was used in a proof-of-concept application as a photoresistor type sensor. The WS₂–pyrene hybrid material was comprehensively characterized by spectroscopic, thermal and microscopy techniques, coupled to density functional theory modelling. The high solubility of the WS₂–pyrene hybrid material allows easy manipulation in wet media, making it suitable for device fabrication. Thus, a two-terminal resistive photosensor was developed and tested for photodetection. The photosensitivity of WS₂ was improved by the presence of covalently attached pyrene by a factor of 2–3, the response linearly dependent on light intensity. Device reaction time was also improved, and critically the photosensor stability was significantly enhanced. Functionalization of exfoliated WS₂ material heals vacancies, oxidation and other damage sites liable to impede photoelectric response. This proof-of-concept study opens the way for incorporation of diverse chromophores active in the visible and/or NIR region of the electromagnetic spectrum to WS₂ in order to stabilise it and broaden its photoresistive sensing applicability.