Luminescence-Based Implied Voltage Imaging of Tandem Solar Cells Using Bandpass Filters

A luminescence-based technique is demonstrated for selectively imaging the implied voltages of tandem solar cells. The luminescence emission is captured using a narrow bandpass filter so that the detected luminescence signal is insensitive to the optical properties of the device, thus, revealing the variations in the implied voltages. The proposed method is validated through simulation and experiments conducted on two-terminal perovskite/silicon tandem solar cells with different structures, optical properties, and compositions (e.g., different bandgaps for the perovskite cells). Implied voltage images of each sub-cell can be determined with a maximum relative error of 1%. The proposed technique can also be used to obtain local current-voltage curves. The method is expected to be a valuable tool for optimizing the performance of tandem solar cells, scaling up tandem devices, investigating local defects, and predicting the ultimate device performance.