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 BaTiO3 (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 (Voc), which suppresses carrier recombination and thus boosts the short-circuit current density (Jsc) 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. The efficiency of Cu(In, Ga)Se2 solar cells is boosted from 4.83% to 16.07% when the BaTiO3 (BTO) depolarization field direction shifts from the opposite to the same direction to the p-n junction electric field. These results unlock an effective strategy to improve the efficiency of a solar cell by the ferroelectric depolarization field.image