Research On Micro-thermoelectric Generator Of Large Temperature Difference And High Voltage

As the energy consumption and environmental pollution become more and more serious,finding clean energy alternatives to traditional energy sources has been an important topic of concern for industry and academia.Researchers have used the Seebeck effect to produce a variety of thermoelectric generators that recycle waste heat from nature and achieve clean electricity generation.Thermoelectric generators are generally classified into block-type thermoelectric generators and micro-thermoelectric generators according to the level of recovered waste heat and size of the generators.Among them,the micro-thermoelectric generator can convert low-grade waste heat?less than 230°C?into electric energy,and is used in the fields of wearable electronic devices,wireless sensors,medical equipment,etc.,and has a very broad application prospect.In the existing literature on micro-thermoelectric devices,the length of the thermoelectric pillars of the vertical micro-thermoelectric generator is often limited by the thickness of the photoresist template,and a large temperature difference cannot be established at both ends of the thermoelectric device,thereby improving the output voltage and power of the vertical micro-thermoelectric generators is a very challenging research work.In this study,a novel micro-thermoelectric generator with large temperature difference and high output voltage was fabricated by depositing Bi₂Te₃ and Sb₂Te₃ on the bottom electrode using a glass template.The thermoelectric device has four sets of thermoelectric arms and establishes a temperature difference of 138 K.At that temperature difference,the maximum output voltage of the generator is 40.89 m V;an average of 10.22 m V per pair of thermoelectric arms is the highest reported in the literature.In addition,the genetor can produce a maximum output power of 19.72?W.After that,the composition and morphology of the thermoelectric materials in the through-holes of the glass template were characterized.The effects of the length and coverage of the thermoelectric arms on the performance of the thermoelectric generator were studied by finite element simulation.Both the experimental results and the simulation results show that it is a very effective method to increase the temperature difference and output voltage of the vertical micro-thermoelectric generator through the glass template.Soldering is a common method for completing electrode connection of micro-thermoelectric devices,and the reliability of the connections between the solder and the device electrode needs to be solved.The shear strength of the solder joints is often related to the interfacial layer structure.The previous research results of our group believe that Co-P film is an effective bump bottom metallization layer?UBM?,which acts as a good interface barrier layer and wetting layer,and has a big improvement effect for the shear strength of the solder joint.However,the mechanical properties of Co-P films and solder joints have not been systematically studied.Based on Co-P films with different P contents?2.3 at.%P-18.8 at.%P?,the shear strength of Sn-3.8Ag-0.5Cu/Co-P solder joints was systematically studied with annealing time?0-1000 h?;the relationship between the shear strength of the solder joint and the fracture morphology and cross-section intermetallic structure was studied.The experimental results show that the Co-8.5 at.%P film can be used as a high-quality UBM to improve the shear strength of the electrode of the micro-thermoelectric device.This also provides a research basis for future research on the reliability of electrode connection of micro-thermoelectric devices.