Improved power conversion efficiency of inverted polymer solar cells by using squaraine additive

A small molecular dye 2,4-bis[4-(N,N-diisobut ylamino)-2,6-dihydroxyphenyl] squaraine (SQ) was used as additive to fabricate inverted polymer solar cells (PSCs) with poly-3 (hexylthiophene) (P3HT) and and [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM), and the influence of of SQ doping ratio on the PSCs performance was studied. The power conversion efficiency (PCE) can be improved from 2.99 % to 3.55 % by adding 6 wt% SQ. The extended absorption region was ascribed to the enhancement of PCE.