Contactless characterization of metastable defects in Cu(In,Ga)Se2 solar cells using time-resolved photoluminescence

• We developed an innovative and unambiguous methodology for the analysis of TRPL decays.
• We studied metastable defects in CIGS solar cells using a contactless optical characterization method.
• The developed characterization technique is proven to be an effective comparative tool between different solar cell performances.
• A more complete understanding of the physics of metastable defects is achieved.

The authors present a contactless optical characterization method for the study of metastable defects in Cu(In,Ga)Se2 solar cells. A methodology for the analysis of time-resolved photoluminescence (TRPL) signals is presented. It leads to the observation of a hysteresis phenomenon regarding the minority carrier dynamics following the activation of the metastable defects. The amplitude of the hysteresis phenomena was compared between CIGS solar cells with different absorber/buffer layer interface properties. It is in these particular spatial regions where the metastable defects can be mostly found. The developed contactless characterization method was compared with classical current–voltage measurements. TRPL leads to a more complete understanding of the physics of metastable defects in terms of quantifying the shift in minority charge carriers dynamics that it induces.