On the Application of Lifetime-Equivalent Defect Densities on Solar Cell Level

The concept of lifetime-equivalent defect density based on lifetime measurements as a measure of electrically active defect density is extended to solar cells using Suns-V $_{\mathrm{oc}}$ measurements. It is found to be superior to previous approaches, and offers defect-specific injection-dependent information. However, the correct application of the presented method requires some knowledge of or reasonable assumptions on sample properties and measurement conditions, in particular, effective intrinsic carrier concentration, doping level, and measurement temperature. Furthermore, it is found that samples with high effective excess carrier lifetime can be susceptible to nonequilibrium related issues when the measurement duration is too short compared with lifetime. The use of series-resistance affected current-voltage curves is found to be error-prone.