New Wide Bandgap Conjugated D‐A Copolymers Based on BDT or NDT Donor Unit and Anthra[1,2‐b:4,3,bʹ:6,7‐cʺ]trithiophene‐8‐12‐dione Acceptor for Fullerene‐Free Polymer Solar Cells

Two donor–acceptor (D‐A) copolymers, P128 and P129, containing benzodithiophene (BDT) and naphthiodithiophene (NDT) donor unit, respectively, and the alike anthra[1,2‐b:4,3,bʹ:6,7‐cʺ] trithiophene‐8‐12‐dione(A3T) as an acceptor unit, are synthesized. The P129 (NDT donor) exhibits enhanced chain plan...

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Published in:Macromolecular chemistry and physics 2022-10, Vol.223 (19), p.n/a
Main Authors: Keshtov, Mukhamed L., Konstantinov, Igor O., Khokhlov, Alexie R., Ostapov, Ilya E., Godovsky, Dimitri Y., Alekseev, Vladimir G., Zou, Yingping, Singhal, Rahul, Singh, Manish Kumar, Sharma, Ganesh D.
Format: Article
Language:English
Subjects:
D‐A copolymers
low HOMO offset
polymer solar cells
power conversion efficiency
solvent vapor annealing
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Summary:Two donor–acceptor (D‐A) copolymers, P128 and P129, containing benzodithiophene (BDT) and naphthiodithiophene (NDT) donor unit, respectively, and the alike anthra[1,2‐b:4,3,bʹ:6,7‐cʺ] trithiophene‐8‐12‐dione(A3T) as an acceptor unit, are synthesized. The P129 (NDT donor) exhibits enhanced chain planarity and linearity of backbone compared to P128 (BDT donor), which leads to a considerable increase in both the light‐harvesting ability and hole mobility. In addition to it, the incorporation of the NDT unit creates a strong modification in the morphology with a well‐mixed interpenetrating nanofibrillar network with an increased donor–acceptor interface in the P129:Y6 bulk heterojunction active layer that leads to a high short‐circuit current density and fill factor. The power conversion efficiency (PCE) of the improved polymer solar cells based on P128:Y6 and P129:Y6 is 6.25% and 14.55%, respectively. The negative HOMO offset (−0.02 eV) at P128/Y6 interface restricts the hole transfer from Y6 to P128 and results in low value of short‐circuit current and thereby poor PCE. Finally, the ternary PSCs are constructed with a weight ratio of 0.5:0.5 between P128 and P129 and the weight component of Y6 is kept constant and the PSC attains a PCE of 16.19%. This increase in the PCE can be attributed to the formation of semiconducting alloy based on P128 and P129 donors and the transformation of HOMO offset from negative (−0.02 eV for Y6/P128) to positive (0.04 eV for Y6/P128:P129). Ternary BHJ polymer solar based on two polymers P128 and P129 and one acceptor Y6 attains PCE of 16.19 %, which is higher compared to binary counterparts. The increase in PCE is linked with the transformation of HOMO offset from negative (−0.02 eV for Y6/P128) to positive (0.04 eV for Y6/P128:P129).
ISSN:1022-1352
1521-3935
DOI:10.1002/macp.202200168