Luminescent GdVO4:Sm3+ quantum dots enhance power conversion efficiency of bulk heterojunction polymer solar cells by Förster resonance energy transfer.

In this work, we report enhanced power conversion efficiency (PCE) of bulk heterojunction polymer solar cells by Förster resonance energy transfer (FRET) from samarium-doped luminescent gadolinium orthovanadate (GdVO₄:Sm³⁺) quantum dots (QDs) to polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) polymer. The photoluminescence emission spectrum of GdVO₄:Sm³⁺ QDs overlaps with the absorption spectrum of PTB7, leading to FRET from GdVO₄:Sm³⁺ to PTB7, and significant enhancements in the charge-carrier density of excited and polaronic states of PTB7 are observed. This was confirmed by means of femtosecond transient absorption spectroscopy. The FRET from GdVO₄:Sm³⁺ QDs to PTB7 led to a remarkable increase in the power conversion efficiency (PCE) of PTB7:GdVO₄:Sm³⁺:PC₇₁BM ([6,6]-phenyl-C₇₁-butyric acid methyl ester) polymer solar cells. The PCE in optimized ternary blend PTB7:GdVO₄:Sm³⁺:PC₇₁BM (1:0.1:1.5) is increased to 8.8% from 7.2% in PTB7:PC₇₁BM. This work demonstrates the potential of rare-earth based luminescent QDs in enhancing the PCE of polymer solar cells. [ABSTRACT FROM AUTHOR]