Incorporation of Designed Donor-Acceptor-Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell

Petri Murto, Shi Tang, Christian Larsen, Xiaofeng Xu, Andreas Sandström, Juuso Pietarinen, Benedikt Bagemihl, Birhan A. Abdulahi, Wendimagegn Mammo, Mats R. Andersson, Ergang Wang, Ludvig Edman

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Cost-efficient thin-film devices that emit in the near-infrared (NIR) range promise a wide range of important applications. Here, the synthesis and NIR application of a series of copolymers comprising poly[indacenodithieno[3,2-b]thiophene-2,8-diyl] (PIDTT) as the host and different donor–acceptor–donor (DAD) segments as the guest are reported. We find that a key design criterion for efficient solid-state host-to-guest energy transfer is that the DAD conformation is compatible with the conformation of the host. Such host–guest copolymers are evaluated as the emitter in light-emitting electrochemical cells (LECs) and organic light-emitting diodes, and the best performance is invariably attained from the LEC devices because of the observed balanced electrochemical doping that alleviates issues with a noncentered emission zone. An LEC device comprising a host–guest copolymer with 4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene as the donor and benzo[c][1,2,5]thiadiazole as the acceptor delivers an impressive near-infrared (NIR) performance in the form of a high radiance of 1458 μW/cm2 at a peak wavelength of 725 nm when driven by a current density of 500 mA/cm2, a second-fast turn-on, and a good stress stability as manifested in a constant radiance output during 3 days of uninterrupted operation. The high-molecular-weight copolymer features excellent processability, and the potential for low-cost and scalable NIR applications is verified through a spray-coating fabrication of a >40 cm2 large-area device, which emits intense and uniform NIR light at a low drive voltage of 4.5 V.
Original languageEnglish
Pages (from-to)1753-1761
Number of pages9
JournalACS Applied Energy Materials
Volume1
Issue number4
DOIs
Publication statusPublished - 2018

Keywords

  • near-infrared
  • NIR
  • large-area device
  • light-emitting electrochemical cell
  • LEC
  • copolymer
  • solution processing

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