Thermoelectrics and High-Efficiency Photovoltaics Lab

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The Thermoelectrics and High-Efficiency Photovoltaics lab has equipment for electrical, thermal, and optical characterization of thin-film thermoelectric and photovoltaic devices. Specifically, our measurement capabilities include high temperature measurements of electrical conductivity, thermal conductivity, and the Seebeck coefficient. We also have equipment to test thermoelectric module power generation. Solar measurements are performed with a light source calibrated for one sun at AM1.5 on a temperature controlled stage. An external quantum efficiency (EQE) setup is currently being assembled to measure photovoltaic devices over a wide spectral range.  In addition, concentrator photovoltaic cell measurements will also be performed with a new instrument capable of electrical characterization with flashed optical intensities of 50 to 2,000 suns.

 

TE lab setup.
Thermoelectrics and High-efficiency Photovoltaics lab in Engineering Science Building (ESB) 1111.

 

High Temperature Thermoelectric Characterization 

Our custom high temperature characterization system was built to measure thermal and electrical properties from 300 K to 1200 K under vacuum.  This system is highly configurable and currently has two cartridge heaters and numerous feed-through ports to probe devices and measure conductivity, Seebeck, and thermal conductivity.

 

  • Kurt Lesker bell jar vacuum system that is capable of reaching pressures as low as ~1e-8 Torr
  • Option for dual cartridge heaters mounted to separate copper blocks for measurements to 900 K or a cartidge heater within a molybdenum stage for measurements to 1200 K
  • SRS 830 digital lock-in amplifier for high temperature measurements of thermal conductivity with the 3-omega method

 

High Temp 1
View of the bell jar and equipment used for high temperature thermoelectric characterization.

 

High Temp 2
Probing a device in the bell jar before pumping it down for measurements.

 

Room Temperature Thermoelectric Characterization 

This setup uses two thermoelectric coolers mounted on a heatsink to measure thermal and electrical properties at room temperature.

 

  • Dual thermoelectric cooler stages for independantly controlling temperature differences to measure the Seebeck coefficient
  • SRS 830 digital lock-in amplifier for room temperature 3-omega measurements of thermal conductivity

 

Room temp setup
Dual TECs used for room temperature thermoelectric measurements.

 

Light & Dark I-V Measurements

The system uses a solar simulator with a certified class A spectrum in three major standards, a thermally controlled stage, and an NREL certified reference cell for accurate measurement

  • Solar Simulator

               o   25mm collimated beam

               o   ASTM, IEC & JIS Class A AM 1.5G output

  • NREL certified Si reference cell for calibration
  • Temperature controlled stage with TE
  • Keithley digital source meter controlled by LabVIEW

 

IV setup.
Solar simulator and photovoltaic light and dark I-V test setup.

 

Quantum Efficiency (QE) Measurements

The System is designed for multi-junction photovoltaic device QE measurement up to four junctions. The system utilizes a lock-in amplifier with an optical chopper and a current pre-amplifier to ensure a strong and clear signal. NIST traceable photodetectors are integrated with the system for calibration and real-time monitoring of the optical power. Currently the system is setup for EQE measurement. Relative IQE measurement will be added in the near future.

  • Spectral Products 100W Tungsten-Halogen lamp
  • Spectral Products 1/4M Monochromator with 3 grating operating from 300nm to 1800nm
  • Princeton Applied Research 5210 Dual Phase Lock-in amplifier
  • Stanford Research Systems SR570 current pre-amplifier
  • NIST traceable Si and InGaAs photodetector for reference measurements
  • Dual Si/InGaAs photodetector for real-time calibration of optical power
  • Four high intensity LED as bias light source
  • Voltage Bias with Keithley digital source meter controlled by LabVIEW program
  • Thermally controlled stage

Concentrated Solar Measurements

The system allows user to study device characteristic such as resistance and efficiency under high solar concentration.

  • Sinton Instruments HCCT-350 flash simulator
  • 50 to 2000 sun peaks
  • Xenon flash source
  • Uniformity  < 2% over 1 cm2 at 1000 sun peak
  • Thermally controlled stage