Rain-Energy Electricity Generator Based On Greenhouse Film Regulated By Friction Interface For Temperature And Humidity Self-Powered Sensing

The efficient operation of intelligent greenhouse cannot be inseparable from the support of sensor network that composed of various sensor nodes.But the traditional power supply is difficult to meet its increasingly complicated needs.Recently,the technology of photovoltaic greenhouse is increasingly mature,but photovoltaic materials are easy to pollute the environment and cannot be recycled.In addition to solar energy,there are also mechanical energies such as wind,rain,and water in the agricultural environment.Especially in areas with abundant rainfall,collecting rain energy to drive low-power sensing nodes is an effective way to supplement traditional power sources.TENG based on the coupling effect of contact electrification and electrostatic induction can efficiently convert mechanical energy into electrical energy,and is widely used in self-powered sensing.Based on this,we directly use greenhouse film as the friction material to construct a fully transparent REG that integrated on the top of the greenhouse.Meanwhile,the energy conversion efficiency has been greatly improved by optimizing the electrification effect and regulating the friction interface.Thus,as a new type of power supply,the self-powered sensing of temperature and humidity in the greenhouse is realized.The main contents and results of this research are as follows:（1）To verify whether the greenhouse film can be used as friction material,the F-REG is prepared to realize the conversion of rain energy into electrical energy.A single-electrode mode IE/F-REG based on the interfacial effect is fabricated by directly using greenhouse film as the friction material,and the transparent and highly conductive PEDOT:PSS solution is spin-coated on the bottom of the film as the electrode.The transmittance of IE/F-REG only decreased by 8%,remaining at 76%,compared to the initial 84%transmittance of the film.After studying its working mechanism,the IE/F-REG can generate continuous electric output under different simulated precipitation conditions.The maximum output voltage is 3 V,and the maximum output power density is 0.07 m W m^-2.The feasibility of using greenhouse film to construct F-REG for rain energy collecting is proved.（2）In order to solve the problem of low energy conversion efficiency due to the charge shielding effect exerted by the electrode.The BE/F-REG is prepared by optimizing the electrification effect,and the electrical output is greatly improved.Inspired by the working mechanism of field-effect transistors,a Cu electrode is introduced on the upper surface of the film as the upper electrode,and the original PEDOT:PSS electrode is used as the lower electrode.Here,the upper/lower electrode act as the source and drain electrode for storing and transferring charges,respectively.When water droplets acting as the gate electrode contact the Cu electrode,the original disconnected components（film/PEDOT:PSS and Cu）are connected to form a closed-loop electrical system,which realizes the conversion from the interfacial effect to the bulk effect.In the simulated rainfall scenario,the maximum output voltage reaches 24.5V（8.2 times of IE/F-REG）.The maximum output power density reaches 0.35 m W m^-2（5 times of IE/F-REG）.（3）In order to solve the problem that rainwater is easily attached to the surface due to the poor hydrophobicity of the film,which hinders the charge transfer process.The superhydrophobic modification of the film through friction interface regulation enables F-REG to have a higher output.After ICP etching,the film possesses superhydrophobic and self-cleaning properties（the contact angle is 157.7°）.At the same time,due to the use of CHF₃ and C₄F₈ for etching,fluorine elements are additionally introduced,which further enhance the electron-gaining ability of the film.Under the same experimental conditions of BE/REG,the maximun output voltage reaches 81 V（3.3 times of BE/F-REG,27 times of IE/F-REG）,and the maximum output power density reaches 38.36 m W m^-2（109.6 times of BE/F-REG,548times of IE/F-REG）.The power conversion efficiency has been significantly improved.（4）In order to further verify the practicability of ICP/F-REG,by optimizing the circuit design,it is used as a sustainable power source to power commercial temperature and humidity sensors.The ICP/F-REG is used as the power source.Through continuous dripping for 6 min to simulate rainfall,the alternating current generated by the ICP/F-REG is rectified by the rectifier bridge to charge a 10μF capacitor（charged to about 6 V）.Then,the charged capacitor is used to power the commercial temperature and humidity sensor,and the sensor is successfully driven to work normally without battery.