The effect of DIO additive on performance improvement of polymer solar cells

A series of polymer solar cells (PSCs) based on poly (diketopyrrolopyrrole-terthiophene) (PDPP3T) and 6,6]-phenyl-C71-butyric acid methyl ester (PC₇₁BM) as active layer were fabricated to investigate the effect of 1,8-diiodooctane (DIO) on the performance of PSCs. The power conversion efficiency (PCE) of PSCs was increased from 3.77 % to 4.37 % for the cells with DIO additive. The underlying reason may be attributed to that DIO additive could make PC₇₁BM more dispersive in the active layer, forming a better bi-continuous interpenetrating network for excition dissociation and charge carrier transport. Therefore, the short circuit current density (J _SC) and fill factor (FF) was increased from 8.25 to 9.18 mA/cm² and from 67.2 % to 70.0 % for the PSCs with DIO additive compared with PSCs without DIO additive.