LIFEIT lifetime measuring system provides a cost effective way to evaluate and monitor CIGS thin film efficiency without
the need to complete a fully assembled solar cell.

The need
Up to now, finding out how good a CIGS film is, requires building a complete solar cell with the manufactured film then
measuring the cell’s efficiency. Building a solar cell takes many steps (see picture above). The process is time
consuming and costly. It is therefore extremely desirable to look for a method to predict the thin film solar cell efficiency
by measurement off the film without the need of actually building a complete solar cell. Once the efficiency controlling
parameter of a solar thin film is identified, the same parameter can also be used to optimize the thin film manufacturing
process. Identifying the parameter and knowing how to measure it are quintessential in cost reduction and quality
control of the thin film solar cell manufacturing process.


Scientific Background
It has been found that the efficiency of a thin film solar cell is correlated with the phosphorescent lifetime of the
photon-excited electrons in the solar thin film. The longer the phosphorescent life time of the minority carriers is, the
longer they would live to migrate to the collection area to generate a larger amount of electrical current, hence higher is
the efficiency. By measuring the phosphorescent life time we would be able to predict the efficiency of the CIGS solar
cell.  
Technical Challenge
The amount of phosphorescent light generated by the electron-hole recombination is very small. To build up a
discernible signal, it requires to collect a lot of photons. Conventional single photon counting instrument is known to be
slow. The first challenge is that the data acquisition rate would be too slow for in-line measurement. The second
challenge is that the setup is not a fully integrated unit, very much designed for bench top operation. The third
challenge is the customization of data acquisition software.

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Your requirements

email:  solar@lifeit.net
     
Call 650 321 8380
CIGS Efficiency monitor by  LIFEIT
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LIFEIT's approach
To speed up the data acquisition rate and improve the signal to noise ratio for weak light detection,  LIFEIT's lifetime
measuring system is characterized with the following design features and components:

  • High brightness and high repetition rate light source
  • Band gap specific excitation light source
  • High speed, high gain detector and low noise detector
  • Time resolved life time measurement digital electronics
  • Efficient light collection optics
  • No-hassle sample alignment design
  • In-line operation ready

Nominal Performance specifications

  • Electronics Time resolution : 8 ps
  • Detector limited time resolution: 300 ps.
  • Saturated count rate: 10 MHz
  • Range: 50 ns to 2 micro-second
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TRPL (Time Resolved Phosphorescence
Lifetime) measuring system by LIFEIT
Substrate
Electrode
CIGS Phosphorescent
Lifetime decay curve
CIGS Phosphorescent
Lifetime decay curve
Typical Photon counting System
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