Laser Treatment as Sintering Process for Dispenser Printed Bismuth Telluride Based Paste

Area of Science:

• Materials Science
• Thermoelectrics
• Additive Manufacturing

Background:

• Bismuth telluride (Bi2Te3) based materials are crucial for thermoelectric applications.
• Dispenser printing offers a novel method for fabricating thermoelectric devices.
• Laser sintering presents a rapid thermal post-treatment technique for printed materials.

Purpose of the Study:

• To investigate laser sintering as a post-treatment for dispenser-printed bismuth telluride thermoelectric pastes.
• To evaluate the impact of laser processing parameters on electrical conductivity and Seebeck coefficient.
• To compare laser sintering performance against traditional tube furnace processing.

Main Methods:

• Utilized a high-power fiber laser (600 W, 1064 nm) with a scanning system for rapid processing.
• Employed a Design of Experiment (DoE) approach to identify key processing parameters.
• Measured sheet resistance, electrical conductivity, and Seebeck coefficient for laser-treated and furnace-treated samples.

Main Results:

• Laser sintering enhanced electrical conductivity in p-type material to 22 S/cm (vs. 15 S/cm furnace).
• N-type material showed significantly lower conductivity (7 S/cm laser vs. 88 S/cm furnace).
• Seebeck coefficients decreased with laser processing for both p-type (40-70 µV/K) and n-type (-110 µV/K) compared to furnace (251 µV/K and -142 µV/K).

Conclusions:

• Laser sintering is a promising, high-speed method for p-type bismuth telluride thermoelectric pastes.
• Further research is needed to optimize laser parameters for n-type materials and Seebeck coefficient.
• Area-specific laser energy density alone may not be sufficient for optimizing the laser sintering process.