ZnS Nanosheets in a Polyaniline Matrix as Metallopolymer Nanohybrids for Flexible and Biofriendly Photodetectors

The current research work reports on the functionalization of a poly-toluenesulfonic acid (p-TSA)-doped polyaniline matrix by ZnS nanosheets. Structural analysis has been performed by X-ray diffraction and X-ray photoelectron spectroscopy. The Rietveld refinement confirms the cubic phase of ZnS as well as the XPS reveals the binding energies of Zn 2p1/2 and Zn 2p3/2 at 1045.85 and 1022.83 eV, respectively, establishing the Zn2+ state. Scanning electron microscopy of ZnS–polyaniline exhibits a different-sized mist-like morphology on both paper and cotton substrates. The tunneling electron microscopy images reveal the ZnS nanosheet with an interplanar spacing of 0.31 nm incorporated in the polyaniline matrix. Further, analysis was carried out through UV–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and dynamic light scattering. The metal–metallopolymer nanohybrid-metal device of this metal–polymer framework was fabricated on flexible and eco-friendly cellulose paper and cotton substrates. The density functional theory approach was adopted for better insight understanding about the synthesized material in terms of band gap, electron affinity, and electronegativity. Ohmic as well as the space charge-limited behavior of current is found responsible for the current–voltage characteristics. This flexible device exhibited an ultrahigh photoresponsivity of 396.479 A W–1 and a giant external quantum efficiency of 1.344 × 105%. Paper and cotton substrate-based devices show significant responsivities of 3.671 and 1.740 mA/W with detectivities of 3.092 × 1010 and 3.470 × 1010 Jones even at 0 V, respectively.