Performance Limitations of Wide‐Gap (Ag,Cu)(In,Ga)Se ₂ Thin‐Film Solar Cells

The effect of absorber stoichiometry in (Ag,Cu)(In,Ga)Se2 (ACIGS) solar cells with bandgaps (Eg) > 1.40 eV is studied on a large sample set. It confirmed that moving away composition from ternary AgGaSe2 by simultaneous reduction Ga and Ag content widens the chalcopyrite single-phase region thereby reduces amount ordered vacancy compounds (OVCs). As consequence, distortion current−voltage characteristics, ascribed to OVCs at back contact, can be successfully avoided. A clear anticorrelation between open-circuit voltage (VOC) short-circuit current density (JSC) detected varying stoichiometry, showing decreasing VOC increasing JSC values for [I]/[III] 0.9. Capacitance profiling reveals doping gradually decreases toward stoichiometric composition, eventually leading complete depletion. observed only such fully depleted samples exhibit perfect carrier collection, evidencing very low diffusion length wide-gap ACIGS films. results indicate surface play minor or passive role device performance. Finally, cell = 0.916 V Eg 1.46 measured, which is, best our knowledge, highest value reported this bandgap date.