Method for determining emitter recombination in Si solar cells using open-circuit voltage decay

A method for determining the emitter recombination current and thereby partitioning the total carrier recombination current into the different sections of a silicon solar cell is demonstrated. The method is destructive, requiring that a set of measurements is made on a cell before and after mechanically roughening the back of the cell. The data include short-circuit current (Jsc), open-circuit voltage (Voc), and asymptotic decay rates for Jsc and Voc. High open-circuit voltage (650 mV) silicon cells are studied using the technique. It is shown that the emitter recombination current is large (1.5×10−13 A/cm2), which is consistent with a band-gap narrowing mechanism. Furthermore, the high voltages are shown to result from unusually long base lifetimes (>300 μs) in 0.3-Ω cm silicon.