Low-temperature admittance spectroscopy for defect characterization in Cu(In,Ga)(S,Se)2 thin-film solar cells.

We present a methodology to use low-temperature admittance measurements for characterizing defects in thin-film Cu(ln,Ga)(S,Se)2 solar cells, which is a major step towards increased performance. We develop the theory behind admittance spectroscopy at both room and low temperature, focusing on the so-called “loss-map” graphical representation. It allows to distinguish the entangled responses of different loss mechanisms and, combined with SCAPS 1- D simulations, leads to a refined interpretation of experimental admittance measurements. Using this methodology on experimental measurements, we identify the likely presence of an interface defect, and extract its activation energy $(\mathrm{E}_{\mathrm{A}}=0.093\text{eV})$ and capture cross-section $(\sigma=2.88\cdot 10^{-18}\text{cm}^{2})$ .