High-performance ternary polymer solar cells using wide-bandgap biaxially extended octithiophene-based conjugated polymers
Journal
Journal of Materials Chemistry C
Journal Volume
6
Journal Issue
26
Pages
6920-6928
Date Issued
2018
Author(s)
Abstract
Ternary organic photovoltaics (OPVs) have recently attracted intense research attention since they have been proven as an effective approach to enhance device performance. We herein describe a new strategy to realize high-performance ternary OPVs by using biaxially extended octithiophene (8T)-based wide-bandgap (Eg) conjugated polymers as the third photoactive component. Owing to the π-π transition of the biaxially extended conjugated side-chains, such polymers exhibit intense absorption in the near-ultraviolet region, in addition to the original intra-charge transfer (ICT) feature arising from the main backbone, revealing a new molecular design for wide-Eg polymers. By further tailoring the polymer backbone with p-type moieties such as thiophene (T) or thienothiphene (TT), two wide-Eg (∼2.0 eV) polymers, P8TT and P8TTT, with absorption wavelengths below 650 nm, were prepared, showing high complementary absorption to the spectra of both the state-of-the-art fullerene-(PTB7-Th:PC71BM) and non-fullerene-based (PBDB-T:ITIC) bulk-heterojunction (BHJ) systems. By providing suitable energy levels, P8TTT was demonstrated to enhance the power conversion efficiency (PCE) of its derived fullerene- and non-fullerene-based ternary blends by 7.58% and 6.60%, respectively, with only a small loading amount (10 wt%). This study manifests a new perspective in wide-Eg material design for realizing efficient ternary BHJ systems. © The Royal Society of Chemistry.
SDGs
Other Subjects
Charge transfer; Energy gap; Fullerenes; Heterojunctions; Polymer solar cells; Solar cells; Absorption wavelengths; Based conjugated polymers; Bulk heterojunction (BHJ); Device performance; Effective approaches; Near-ultraviolet regions; Organic photovoltaics; Power conversion efficiencies; Conjugated polymers
Publisher
Royal Society of Chemistry
Type
journal article