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Previously we have reported a general strategy to achieve solution-processed, doped films with a wide range of workfunctions (3.0–5.8 eV), by charge-doping of conjugated polyelectrolytes and then internal ion-exchange to give self-compensated (SC), heavily doped polymers. These SC doped polymers have been demonstrated to give good ohmic contacts processed ohmic contacts for high-performance light-emitting diodes, solar cells, photodiodes and field-effect transistors. For SC doped polymer, the mobile carriers on the polymer backbone are compensated by covalently-tethered counter-ions. The covalently-tethered counter-ion prevents dopant migration. The excess covalently-bonded counter-ions together with spectator anions provides solvent processability. We have now synthesized and characterized an extended series of SC p-doped polymer with different covalently-tethered counter-anions and spectator cations. We report the detail structural-properties of these materials on their workfunctions, film air and thermal stability, and hence device performance. We further found insignificant ion-layering in these doped polymer film by variable-angle X-ray photoemission spectroscopy. Therefore the WF of these SC p-doped films is strongly dominant by its chemical potential with minimal surface dipole contribution. The effect of ions in these doped polymers gained here is critical to the future development of materials for the emerging field of bioelectronics.
[1]Tang, Choo, Ang, Keerthi, Tan, Nursyafiqah, Kugler, Burroughes, Png, Chua, Ho, Nature 539, 536-540 (2016)
[2]Png, Ang, Teo, Choo, Tang, Belaineh, Chua, Ho, Nature Commun. 7:11948 (2016)
[3]Seah, Tang, Png, Keerthi, Zhao, Guo, Yang, Ho, Chua, Adv. Funct. Mater. DOI: 10.1002/adfm.201606291 (2017)
[4]Yang, Seah, Guo, Tan, Zhou, Matsubara, Nakamura, Png, Ho, Chua, Organic Electronics, 37, 491 (2016)
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