On the Design of Host–Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?
Journal article, 2019

It has recently been demonstrated that light-emitting electrochemical cells (LECs) can be designed to deliver strong emission with high efficiency when the charge transport is effectuated by a majority host and the emission is executed by a minority guest. A relevant question is then: should the guest be physically blended with or chemically incorporated into the host? A systematic study is presented that establishes that for near-infrared-(NIR-) emitting LECs based on poly(indacenodithieno[3,2-b]thiophene) (PIDTT) as the host and 4,7-bis(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophen-2-yl)benzo[c][1,2,5]-thiadiazole (SBS) as the guest the chemical-incorporation approach is preferable. The host-to-guest energy transfer in LEC devices is highly efficient at a low guest concentration of 0.5%, whereas guest aggregation and ion redistribution during device operation severly inhibits this transfer in the physical-blend devices. The chemical-incorporation approach also results in a redshifted emission with a somewhat lowered photoluminescence quantum yield, but the LEC performance is nevertheless very good. Specifically, an NIR-LEC device comprising a guest-dilute (0.5 molar%) PIDTT-SBS copolymer delivers highly stabile operation at a high radiance of 263 µW cm−2 (peak wavelength = 725 nm) and with an external quantum efficiency of 0.214%, which is close to the theoretical limit for this particular emitter and device geometry.

near-infrared emission

intramolecular energy transfer

light-emitting electrochemical cells

host–guest copolymers

Author

Shi Tang

Umeå University

Petri Henrik Murto

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Ergang Wang Group

Flinders University

Jia Wang

Umeå University

Christian Larsen

Umeå University

Mats Andersson

Flinders University

Ergang Wang

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Ergang Wang Group

L. Edman

Umeå University

Advanced Optical Materials

2195-1071 (eISSN)

1900451

Subject Categories

Other Chemical Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1002/adom.201900451

More information

Latest update

11/8/2019