Power loss analysis via photoluminescence

This thesis presents six methods to improve the characterisation of solar cells via photoluminescence techniques. The first two methods use photoluminescence images under combined voltage bias and illuminations to calculate spatially resolved essential parameters. These quantitative images of parameters such as current density, dark saturation current density J01 and J02 and efficiency are useful to check the location and magnitude of the defects. Therefore the performance of the solar cell could be well-characterised using these approaches. The third method is the series resistance separation method. A series resistance image can be separated into natural and defect-related components. Through this, the series resistance of the solar cell can be better understood. The fourth method is the front and rear defect separation method. By utilising this method, the vertical characterisation of solar cells can be achieved. The fifth method is the area calculation method. This method calculates the active area and total area of the solar cell; and simultaneously, the position of the active area is recorded, which can be used for further analysis. The sixth method is the voltage and effective lifetime imaging method. The core advantages of this method are that it virtually eliminates the horizontal balancing current when the cell is on open-circuit and no calibration is required.All the methods explained in this thesis are feasible for use in industry. This is because all the methods only require an existing commercial photoluminescence system and no additional equipment is needed. The data acquisition and calculation time are in the order of seconds or minutes