Flexible Piezoelectric Nanogenerators Based On P（VDF-TrFE）/CsPbBr₃ Quantum Dots Composite Films

In the past few decades,many researchers have been working on the development of energy conversion systems and eco-friendly sustainable energy storage for combating climate change,global energy crisis and environmental pollution.However,piezoelectric materials have the ability to convert energy in the environment into electrical energy.As the active building block of piezoelectric devices,piezoelectric materials have received more and more attention in the fields of in actuators,piezotronics,self-powered sensors,and energy harvesting devices.Although various piezoelectric semiconductors such as ZnO,GaN,CdS or ZnS,and piezoelectric ceramics such as PZT and Ba TiO₃,have been demonstrated as superior in terms of energy conversion efficiencies and piezoelectric coefficients,they still suffer from low durability,poor toughness,high toxicity and heavy weight,limiting their practical implementation in harsh environment.Compared to the above inorganic materials,polyvinylidene fluoride（PVDF）and its copolymers polyvinylidene fluoride-trifluoroethylene（P（VDF-TrFE））have the advantages of flexibility,conformability,lightweight,and simple processing,which can greatly remedy the shortcomings of inorganic materials.However,polymer-based composite piezoelectric materials combined the high piezoelectric coefficients of inorganic piezoelectric materials and the flexibility of organic polymers.By adding some fillers to the organic polymer matrix,piezoelectric composite nanomaterials with high piezoelectric properties,good flexibility and long service life can be prepared.P（VDF-TrFE）is a semi-crystalline polymer with five different crystal phases.Its piezoelectric properties are mainly related to theβ-phase.Theβ-phase content of P（VDF-TrFE）can be increased by nanoparticle induction,uniaxial stretching,and high electric field polarization.This subject prepared a P（VDF-TrFE）/CsPbBr₃ quantum dots（QDs）composite piezoelectric material.Detailed research have been done in the aspects of process optimization,doping modification,stability and energy harvesting applications in human motion.The specific conclusions are as follows:In terms of process optimization,in order to reduce the surface defects of the film,a vacuum drying oven was used to dry the film,and the film was subjected to high-pressure polarization treatment.In terms of modification,the piezoelectric properties of P（VDF-TrFE）/CsPbBr₃ QDs composite piezoelectric films of different CsPbBr₃ QDs were studied.The piezoelectric coefficient of PENG of the P（VDF-TrFE）/CsPbBr₃ QDs composite film of 0.3%CsPbBr₃ QDs increased from 15.5 p C N^-1 to 24.5 p C N^-1,and the open circuit voltage and short circuit current were increased by 2.5 times and 2.2 times.In terms of stability and collection of human movement energy.The optimized PENG was hit with a linear motor for several months to verify its stability.The experimental results showed that even after 2 months,no significant decline in output characteristics was observed.PENG’s fatigue test showed its potential as a robust wearable mechanical energy harvester.In order to verify its flexibility and the potential to detect human movement,the piezoelectric energy generated from these devices have been studied under several simple human actions,for example,finger tapping,bending,wind blowing,etc.,showing its huge application potential in energy harvesting and sensing.