Comparative study on the effects of alkylsilyl and alkylthio side chains on the performance of fullerene and non-fullerene polymer solar cells
Journal article, 2020
Two novel high gap donor polymers – PBDTTSi-TzBI and PBDTTS-TzBI, based on imide-fused benzotriazole (TzBI) with asymmetric side chains and alkylsilyl (Si) or alkylthio (S) substituted 4,8-di(thien-2-yl)benzo-[1,2-b:4,5-b′]dithiophene (BDTT) – are successfully synthesized. The effect of the side chain variation on the photophysical, morphological and photovoltaic properties of blends of these polymers with fullerene and non-fullerene acceptors is investigated. The PBDTTSi-TzBI polymer shows a deeper highest occupied molecular orbital energy level, which results in higher open-circuit voltages. Nevertheless, the polymer solar cells fabricated using PBDTTS-TzBI in combination with PC71BM afford a higher power conversion efficiency of 7.3% (vs 4.0% for PBDTTSi-TzBI:PC71BM). By using the non-fullerene acceptor ITIC, the absorption of the blends extends to 850 nm and better device efficiencies are achieved, 6.9% and 9.6% for PBDTTSi-TzBI:ITIC and BDTTS-TzBI:ITIC, respectively. The better performance of the PBDTTS-TzBI:ITIC-based devices is attributed to the strong and broad absorption and balanced charge transport, and is among the best performances reported for non-fullerene solar cells based on TzBI-containing polymer donors.
Non-fullerene solar cells
Alkylsilyl
Organic photovoltaics
Alkylthio
Side chain optimization
High gap polymers
Author
Zewdneh Genene
Ambo University
Addis Ababa University
Asfaw Negash
Addis Ababa University
Universiteit Hasselt
Birhan A. Abdulahi
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Addis Ababa University
Raghavendran Thiruvallur Eachambadi
Universiteit Hasselt
Zhen Liu
Vrije Universiteit Brussel (VUB)
Niko Van Den Brande
Vrije Universiteit Brussel (VUB)
Jan D'haen
Universiteit Hasselt
Ergang Wang
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
K. Vandewal
Universiteit Hasselt
Wouter Maes
Universiteit Hasselt
Jean Manca
Universiteit Hasselt
W. Mammo
Addis Ababa University
Shimelis Admassie
Addis Ababa University
South China University of Technology
Organic Electronics: physics, materials, applications
1566-1199 (ISSN)
Vol. 77 105572Subject Categories
Materials Chemistry
Energy Systems
DOI
10.1016/j.orgel.2019.105572