Application of non-contact quantum efficiency measurement for solar cell fabrication process insights

We demonstrate the application of non-contact external quantum efficiency (EQE) measurements as potential in-line inspection for solar cell mass production. The technique, based on electroluminescence excitation spectroscopy (ELE), is several times faster than conventional contacted EQE measurements, and enables on-the-flight contactless assessment of spectral response . To simulate a manufacturing environment, EQE of a batch of 200 bifacial PERC solar cells are investigated. This allows statistical analysis of the interplay between fabrication process conditions, cell current–voltage characteristics and results from other in-line inspection tools. The study shows that non-contact EQE can be used to detect variation in POCl 3 diffusion and PECVD processes at cell level and without direct contact to the device. It is also possible to predict EQE on passivated, non-metallized diffused wafers. This provides powerful information in predicting end-of-line cell parameters, as well as to sort and remove low performing wafers prior to printing to eliminate metal paste wastage. • Non-contact external quantum efficiency measurement allows fast spectral response inspection of solar cells. • Large sample size provides high confidence insights into fabrication processes. • Potential metal paste saving from measurements on wafers prior to metallization.