Comparative study on the effects of alkylsilyl and alkylthio side chains on the performance of fullerene and non-fullerene polymer solar cells

Zewdneh Genene, Asfaw Negash, Birhan A. Abdulahi, Raghavendran Thiruvallur Eachambadi, Zhen Liu, Niko Van den Brande, Jan D'Haen, Ergang Wang, Koen Vandewal, Jean Manca, Wendimagegn Mammo, Shimelis Admassie

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article number105572
JournalOrganic Electronics
Volume77
DOIs
Publication statusPublished - Feb 2020

Bibliographical note

Funding Information:
ZG and AN contributed equally to this work. The authors acknowledge financial support from Hasselt University ( BOF bilateral scientific cooperation ). WM, SA, ZG, BA and AN gratefully acknowledge financial support from the International Science Program (ISP), Uppsala University , Sweden. WM, NV, KV and JM thank the Research Foundation – Flanders ( FWO – Vlaanderen ) for continuous financial support (projects G.0B67.15 N, G.0D01.18 N and G.0B27.18 N).

Publisher Copyright:
© 2019 Elsevier B.V.

Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.

Keywords

  • Alkylsilyl
  • Alkylthio
  • High gap polymers
  • Non-fullerene solar cells
  • Organic photovoltaics
  • Side chain optimization

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