Flexible photodetector for broadband detection using wurtzite phase CuFeS2 nanoparticles

Abstract

In the realm of electronic devices, a rising demand for flexible and enhanced performance has emerged. Current research predominately centres on optoelectronics and sensors within the flexible devices’ domain. A flexible photodetector, utilizing CuFeS2 (CFS), is crafted on a cellulose paper substrate. Employing the hand printing method, a thin film of CFS on a graphene-based transporting layer is fabricated. The wurtzite phase of the material synthesized using microwave−assisted method is confirmed by X−ray diffraction (XRD) and Raman spectroscopy, with compositional details provided by energy dispersive X−ray analysis. Comprehensive XRD based calculations of size, stress, strain and energy density are conducted using three different models - Uniform Deformation Model, Uniform Stress Deformation Model and Uniform Deformation Energy Density Model. The average particle size, strain and stress from the three different models is found to be 9⋅73 nm, 1⋅35 × 10−3, 55⋅05 MPa along with calculated energy density value of 78⋅421 kJ m−3, respectively. Band gap calculations utilizing diffuse reflectance yielded an optical bandgap of 1⋅23 eV for the CFS thin film. The fabricated photodetector is studied for different illumination wavelengths, 450 nm, 520 nm, 570 nm, 620 nm and 940 nm, to determined device parameters. The optimum rise time, decay time, responsivity, and specific detectivity for wavelength of 520 nm are 6⋅43 s, 7⋅01 s, 0⋅0319 mA W−1 and 1⋅173 × 1010 Jones. The photoresponse of the fabricated device bended to 2⋅5− and 5−mm radii is studied to recognize suppleness. The photoresponse showed the photocurrent decreases with increase of bending. The observed traits under bending switched to initial on flattening the thin film.