Forster resonance energy transfer in p-DTS(FBTTh2)(2)- p-SIDT(FBTTh2)(2) small molecule ternary blend bulk-heterojunction solar cells for enhanced power conversion efficiency

Abstract

In this study, we demonstrate a new all small molecule ternary bulk heterojunction (BHJ) organic solar cells (OSCs) incorporating two small molecule (SM) (7,7'-[4,4-Bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']d ithiophene-2,6-diyllbis[6-fluoro-4-(5'-hexyl-[2,2'-bithiophen]-5yl)benzo [c][12,5] thiadiazole] (p-DTS (FBTTh2)(2)) and benzo [1,2-b:4,5-b]bis (4,4'-dihexyl-4H-silolo[3,2-b]thiophene-2,2'-diyl)bis(6-fluoro-4-(5'-hexyl-[2,2'-bithiophene]-5-yl)benzo[c][1,2,5] thiadiazole (p-SIDT(FBTTh2)(2)) as a donor and fullerene derivative ([6,6]-Phenyl-C-71-butyric acid methyl ester (PC71BM)) as an acceptor. By varying SM donor ratios, we observed an enhancement of power conversion efficiency (PCE) from similar to 7% to similar to 9%. This increase in the PCE can be attributed to the Forster resonance energy transfer (FRET) as confirmed by steady-state photoluminescence measurements. (C) 2019 Elsevier B.V. All rights reserved.