Research On The Synergistic Effect Of Photothermal-pyroelectric And Their Energy Harvesting Application

With the improvement of the economic level,people’s demand for energy continues to grow,and the global energy crisis has become more and more serious.However,there is a large amount of neglected energy in human daily life and industrial production.Therefore,it is of great significance to study energy harvesters that can collect and utilize energy in the environment.Pyroelectric materials can convert thermal energy into electrical energy via temperature fluctuations of the environment,which has been widely used in thermal energy harvesting research.However,the temperature fluctuation of the natural environment is small and the fluctuation frequency is low,resulting in low energy collection efficiency.To solve the above problems,we proposed the photothermal-pyroelectric synergistic effect and prepared a photothermal-pyroelectric heterostructure energy harvester（PPH）.Compared with a single pyroelectric energy harvester,PPH has a higher energy harvesting efficiency and broader application space.In this paper,2-2 mode PPH was prepared by using titanium sesquioxide-polymethyl methacrylate（Ti₂O₃-PMMA）photothermal film and barium strontium titanate(Ba_xSr_1-xTi O₃（x=0.67～0.90）,referred to as BST)ceramics and tested the related properties of the Ti₂O₃-PMMA photothermal film,BST ceramics and PPH.The main work and results are as follows:（1）The high-quality Ti₂O₃-PMMA photothermal film was prepared by blade coating.Under the illumination with irradiance of 100 m W/cm²,as the increase of Ti₂O₃ mass fraction and thickness,the temperature differenceΔT of Ti₂O₃-PMMA photothermal film gradually increases,and the temperature change rate d T/dt shows a trend of first increasing and then decreasing.Especially,when the mass fraction of Ti₂O₃ is 15%and the thickness is 20μm,the d T/dt of the photothermal film is 8℃/s and theΔT is 23.8℃,showing the excellent photothermal conversion efficiency.（2）BST ceramics were prepared by solid-phase sintering method,and the effects of ceramic microstructure and sintering temperature on pyroelectric properties were explored.The results show that:（i）As the increase of the Ba element content,the ceramic crystal structure changes from cubic phase transition to tetragonal phase,the ferroelectricity of the ceramic is enhanced,and its Curie temperature increases from 21℃to 95℃.Generally,a high pyroelectric response can be obtained at ferroelectric-paraelectric phase transition temperature.（ii）As the sintering temperature increases,the pyroelectric coefficient shows a trend of first increases and then decreases.In partical,when the sintering temperature is 1400℃,the best pyroelectric coefficient p=10.26×10^-4 C m^-2 K^-1 is obtained at 35℃.（3）PPH is prepared using photothermal film and ceramics,and the synergistic effect of photothermal-pyroelectricity is used to increase the pyroelectric energy harvesting.The results show that:（i）When the photoperiod is 40 s,theΔT and d T/dt of PPH are 5.08℃and 0.44℃/s,respectively,which are about 162.35%and 160.27%of the BST pyroelectric energy harvester（BPH）.The short-circuit current and open-circuit voltage of PPH are 51.89 n A and 64.68 m V,which are approximately 10.8 times and 2.6 times as much as BPH.（ii）When an external 90MΩresistor is connected,the maximum output power of PPH is 0.128 n W,the bulk power density is 0.464μW/cm³,and it has excellent good fatigue resistance.In summary,this thesis systematically explores the effect of different Ti₂O₃ mass fraction and thickness on the thermal responsivity of Ti₂O₃-PMMA photothermal film and the effect of different composition and sintering temperature on the pyroelectric properties of BST ceramics.The photothermal-pyroelectric heterostructure energy harvester was prepared,and the synergistic effect of photothermal-pyroelectricity was used to significantly improve the solar energy collection efficiency of the device.It provides new ideas for improving the energy collection efficiency of pyroelectric materials in the natural environment,and expands the application of pyroelectric materials in the field of energy harvesting.