AC analysis of temperature effects on conversion efficiency of CuInGaSe2 solar cells

The temperature effect on a CuInGaSe₂ (CIGS) solar cell was investigated in the temperature range -10 to 80°C using direct current (DC) and alternating current (AC) characteristic analysis of CIGS solar cells. The change rates of short-circuit current density (J_sc), open-circuit voltage (V_oc), fill factor (FF) and efficiency (η) with respect to temperature were investigated. In addition, the variation of impedance, total capacitance and dynamic resistance due to the temperature change implied that the width of the depletion region in a p-n junction shrank, and the effective minority carrier lifetime (τ_eff) decreased. Consequently, J_sc changed slightly due to the balance between the variation of the energy bandgap (E_g) and τ_eff. However, V_oc linearly decreased due to the relationship of E_g when the temperature increased. From these results, it has been concluded that V_oc plays an important role in the characteristics of the CIGS solar cell with change of temperature.