Flexible ultraviolet photodetector based on flower-like ZnO/PEDOT:PSS nanocomposites

An excellent flexible nanocomposites films, which consists of flower-like ZnO and conducting polymer (poly (3,4ethelyenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) on flexible transparent plastic sheets were prepared and reported its unusual negative UV photoresponse, that is increasing resistance in nanocomposite under UV illumination. Nanocomposite (NC) films with varying ZnO loading are used to study the UV photoresponse. Negative photoresponse decreases after a critical concentration of ZnO in NC. Different ZnO concentration NC films were prepared using a simple drop-casting method on flexible transparent plastic sheets. Well-arranged flower-like structured ZnO were prepared by a wet chemical method. A structural investigation based on X-ray diffraction pattern shows the small variations in structural parameters such as lattice constant, crystalline size, microstrain, and dislocation density when ZnO mix with polymer. UV spectroscopy reveals the bandgap variation due to increasing ZnO loading in NC. The photoluminescence study of ZnO gives a broad emission ranging from 485 to 630 nm under an excitation wavelength of 330 nm. Raman spectroscopic and FT-IR studies were also done to know the vibrational properties of prepared samples. Thermogravimetric analysis of prepared NC shows the thermal stability of NC increases with increasing ZnO concentration in NC. Photoresponsivity of NC films was studied by varying ZnO concentration in NC towards UV radiation. Negative photoresponse is changing with ZnO concentration in fixed PEDOT:PSS concentration.