Power Collection Efficiency Mapping: A New Electroluminescence-Based Measure of Power Transport Efficiency

In this study, we present a power-centric enhancement to the photo-current collection efficiency method, introducing the concept of power collection efficiency. The photo-current collection efficiency, defined as the derivative of the cell current with respect to locally generated photo-current, serves as a quantitative metric (ranging from 0 to 1) that effectively measures the efficiency of current transport to the device terminals. Traditionally, photo-current efficiency maps are generated using an electroluminescence imaging technique. Expanding on this method, we propose the generation of efficiency maps that quantify the ratio between locally generated power within the solar cell and the power extracted at the contacts. This new approach not only captures current losses but also incorporates voltage losses, offering a more comprehensive analysis of power losses. To demonstrate the proposed method, we apply it to a silicon heterojunction solar cell under constant illumination, demonstrating its potential for detailed, spatially resolved power loss diagnostics.