High‐Performance All‐Polymer Solar Cells Enabled by n‐Type Polymers with an Ultranarrow Bandgap Down to 1.28 eV. Issue 30 (9th June 2020)

• Record Type: Journal Article
• Authors: Feng, Kui; Huang, Jiachen; Zhang, Xianhe; Wu, Ziang; Shi, Shengbin; Thomsen, Lars; Tian, Yanqing; Woo, Han Young; McNeill, Christopher R.; Guo, Xugang
• Is Part Of: Advanced materials. Volume 32:Issue 30(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-06-09
• Subjects: all‐polymer solar cells -- electron mobility -- n‐type polymers -- power conversion efficiency -- ultranarrow bandgap; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202001476
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Compared to organic solar cells based on narrow‐bandgap nonfullerene small‐molecule acceptors, the performance of all‐polymer solar cells (all‐PSCs) lags much behind due to the lack of high‐performance n‐type polymers, which should have low‐aligned frontier molecular orbital levels and narrow bandgap with broad and intense absorption extended to the near‐infrared region. Herein, two novel polymer acceptors, DCNBT‐TPC and DCNBT‐TPIC, are synthesized with ultranarrow bandgaps (ultra‐NBG) of 1.38 and 1.28 eV, respectively. When applied in transistors, both polymers show efficient charge transport with a highest electron mobility of 1.72 cm 2 V −1 s −1 obtained for DCNBT‐TPC. Blended with a polymer donor, PBDTTT‐E‐T, the resultant all‐PSCs based on DCNBT‐TPC and DCNBT‐TPIC achieve remarkable power conversion efficiencies (PCEs) of 9.26% and 10.22% with short‐circuit currents up to 19.44 and 22.52 mA cm −2, respectively. This is the first example that a PCE of over 10% can be achieved using ultra‐NBG polymer acceptors with a photoresponse reaching 950 nm in all‐PSCs. These results demonstrate that ultra‐NBG polymer acceptors, in line with nonfullerene small‐molecule acceptors, are also available as a highly promising class of electron acceptors for maximizing device performance in all‐PSCs. Abstract : n‐Type polymer semiconductors with a broad absorption and ultranarrow bandgap down to 1.28 eV are synthesized. When applied as electron acceptor materials, a power conversion efficiency of over 10% with a photoresponse reaching 950 nm is realized for all‐polymer solar cells.