Robust\nPhotodetectable Paper from Chemically Exfoliated\nMoS₂–MoO₃ Multilayers

Abstract

Photodetectors,\nwhich are capable of detecting light with varied\nwavelength, have nowadays been widely applied onto emerging fields\nsuch as security, entertainment, healthcare, environment, and so on.\nAs the one with a two-dimensional layered structure, molybdenum disulfide\n(MoS₂) possesses striking optical and electrical properties\nthat can be used in photodetecting, yet the challenges remain in terms\nof material processing, device fabrication simplicity, and enhancement\nof overall photodetection performance. In this work, a photodetectable\npaper based on a mixture of double-phased MoS₂ (1T and\n2H) and MoO₃ was successfully fabricated through a straightforward\nroute, that is, chemical exfoliation and deposition of MoS₂ powder on a flexible cellulose ester membrane, followed by inkjet-printed\nPEDOT:PSS as electrodes. The obtained device shows varied sensitivity\nto the light with different wavelengths. Compared with that under\ngreen and red lights, the prepared photodetector has the highest internal\nquantum efficiency (0.063%) and responsivity (0.134 mA W^–1), while having longest response/recovery time (17.5/15.3 s) when\nilluminated with purple light (405 nm). The achieved responsivity\nis much higher than other reported liquid exfoliation- and solution-derived\nMoS₂ photodetectors. This is ascribed to (1) the enhanced\nphotoelectron generation caused by both MoS₂ and MoO₃ and (2) the good electric conductivity and efficient charge\ntransport caused by the metallic 1T MoS₂. This work demonstrates\nthe feasibility of fabricating the MoS₂-based photodetector\nwith excellent performance through a simple exfoliation/filtration\nand inject printing route, and the detailed study on the response\nto light with different wavelengths unveils the interaction between\nthe device and the incident light, further broadening the potential\napplications of such design.