Boosting Efficiency of CIGS Solar Cell by Ferroelectric Depolarization Field

Increasing the electric field in a solar cell is of importance to alleviate the carrier recombination and thus to increase the power conversion efficiency (PCE). In this paper, a strategy is reported to enhance the internal electric field of Cu(In,Ga)(Se,S) 2 (CIGS) solar cells by inserting a ferroelectric BaTiO 3 (BTO) layer into the device for the first time. The BTO location in the CIGS solar cell is found to play a vital role in the performances, which is due to the adjustment of the direction of BTO depolarization field. Impressively, the PCE is increased from 4.83% to 16.07% when the BTO depolarization field direction shifts from the opposite to the same direction to the p–n junction electric field. The improved PCE is due to the enhanced open‐circuit voltage ( V oc ), which suppresses carrier recombination and thus boosts the short‐circuit current density ( J sc ) from 14.09 to 32.69 mA cm −2 . These results unlock an effective strategy to improve the PCE of a CIGS solar cell by the application of a ferroelectric depolarization field. The facile deposition of BTO via sputtering method at room temperature enables its wide application in other solar cells to boost the PCEs.