Dual sensor technique for the advanced characterization of recombination parameters in photovoltaic materials

This work addresses the frequent discrepancy between transient photoconductive decay and transient photoluminescence decay. With this dual sensor technique, one measures the transient PC and PL decay simultaneously with the same incident light pulse, removing injection level uncertainty. Photoconductive decay measures the transient photoconductivity, Δσ(t). PCD senses carriers released from shallow traps as well as the photo-generated electron-hole pairs. In addition, variations in carrier mobility with injection level (and time) contribute to the decay time. PL decay senses only electron-hole recombination via photon emission. Theory and experiment will show that the time dependence of the two techniques can be quite different at high injection.