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.