A Novel Wide‐Bandgap Polymer with Deep Ionization Potential Enables Exceeding 16% Efficiency in Ternary Nonfullerene Polymer Solar Cells. (17th May 2020)

• Record Type: Journal Article
• Authors: Zhang, Ying; Liu, Delong; Lau, Tsz‐Ki; Zhan, Lingling; Shen, Dong; Fong, Patrick W. K.; Yan, Cenqi; Zhang, Shaoqing; Lu, Xinhui; Lee, Chun‐Sing; Hou, Jianhui; Chen, Hongzheng; Li, Gang
• Is Part Of: Advanced functional materials. Volume 30:Number 27(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-17
• Subjects: deep HOMO level -- efficient ternary PSCs -- generality -- improved light stability -- WBG polymer donor; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201910466
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Ternary strategies have attracted extensive attention due to their potential in improving power conversion efficiencies (PCEs) of single‐junction polymer solar cells (PSCs). In this work, a novel wide bandgap polymer donor ( E g opt ≈ 2.0 eV) named PBT(E)BTz with a deep highest occupied molecular orbital (HOMO) level (≈−5.73 eV) is designed and synthesized. PBT(E)BTz is first incorporated as the third component into the classic PBDB‐T‐SF:IT‐4F binary PSC system to fabricate efficient ternary PSCs. A higher PCE of 13.19% is achieved in the ternary PSCs with a 5% addition of PBT(E)BTz over binary PSCs (12.14%). Similarly, addition of PBT(E)BTz improves the PCE for PBDB‐T:IT‐M binary PSCs from 10.50% to 11.06%. The study shows that the improved PCE in ternary PSCs is mainly attributed to the suppressed charge carrier recombination and more balanced charge transport. The generality of PBT(E)BTz as a third component is further evidenced in another efficient binary PSC system—PBDB‐TF:BTP‐4Cl: an optimized PCE of 16.26% is realized in the ternary devices. This work shows that PBT(E)BTz possessing a deep HOMO level as an additional component is an effective ternary PSC construction strategy toward enhancing device performance. Furthermore, the ternary device with 5% PBT(E)BTz displays better thermal and light stability over binary devices. Abstract : Incorporation of a small portion of a novel polymer donor named PBT(E)BTz with a deeper highest occupied molecular orbital level than that of the host materials is proven promising to construct highly efficient ternary polymer solar cells (PSCs). In addition to the role of a "solid additive" for ternary PSCs, PBT(E)BTz shows great potential to be a thermal and light stabilizer in ternary PSCs.