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Overcoming the water oxidative limit for ultra-high-workfunction hole-doped polymers
Qi-Mian Koh1, Cindy Guanyu Tang2, Mervin Chun-Yi Ang1
1Department of Chemistry, National University of Singapore, Singapore, Singapore.
Nature Communications
|June 8, 2021
Summary
We demonstrate polymer organic semiconductors with ultrahigh work functions up to 5.9 eV, overcoming previous limits. This breakthrough enables stable, solution-processable soft materials for advanced electronic applications.
Area of Science:
- Materials Science
- Organic Electronics
- Electrochemistry
Background:
- The maximum work function of hole-doped semiconductors in ambient conditions is typically limited to ~5.25 eV by the water-oxidation reaction.
- This limitation is attributed to the oxidation potential of air-saturated water, constraining semiconductor performance.
Purpose of the Study:
- To investigate polymer organic semiconductors for achieving work functions exceeding the conventional 5.25 eV limit.
- To understand and overcome the factors limiting work function in hole-doped organic semiconductors.
- To explore the potential of these materials in applications like batteries and bio-electronics.
Main Methods:
- Hole-doping of polymer organic semiconductors.
- Utilizing large super-acid anions (perfluoroalkyl-sulfonylimidosulfonyl) to raise the oxidation potential for hydronium generation.
- Characterization of work function, stability in ambient conditions, and thermal properties of the resulting polymer films.
Main Results:
- Achieved work functions up to 5.9 eV in hole-doped polymer organic semiconductors, surpassing the 5.25 eV limit.
- Demonstrated stability of these high work function polymers in ambient conditions.
- Identified that de-doping is governed by counter-balancing anions and their hydrated complexes, not bulk water oxidation.
Conclusions:
- The work function of polymer organic semiconductors is not fundamentally limited by water oxidation, but by the nature of the counter-balancing anion.
- Large super-acid anions can be used to achieve ultrahigh work functions and stable hole-doped states.
- These findings pave the way for developing solution-processable soft materials with tunable ultrahigh work functions for diverse electronic applications.
