Fine‐Tunable Electronic Energy Levels of Mixed‐Metal Prussian‐Blue Alloy Nanoparticles. Issue 5 (20th April 2017) - Ishizaki, Manabu
Abstract: A specific electronic interaction among metal ions emerges in solution‐processed films of coordination polymer (CP) nanoparticles (NPs). The most classic CP, Prussian blue (PB), is alloyed with Ni to form Fe x Ni3− x [Fe(CN)6 ]2 showing an identical X‐ray crystallographic phase in all composition ratios of 0≤ x ≤3. By surface modification using [Fe(CN)6 ] 4−, the PB alloy NPs are dispersed into water, and spin‐coated films of the NPs adhere to indium‐tin‐oxide substrates via a low‐temperature heating process at 100 °C. It is revealed that systematic fine tuning of the electronic energy levels is optically and electrochemically possible in the films by controlling the composition ratios. This is possible due to the d ( t 2g )– π *(C≡N − ) electronic conjugation among three redox‐active iron species, Fe II −C≡N, Fe III −C≡N, and Fe III −N≡C, which coexist by alloying with Ni. The heating process conducts the restoration of discontinued d–π* bonding networks among the NPs. Abstract : The mixed‐metal PB alloy NPs, Fe x Ni3− x [Fe(CN)6 ]2, show an identical X‐ray crystallographic phase in all composition ratios of 0≤ x ≤3. It is revealed that systematic fine tuning of the electronic energy levels is optically and electrochemically possible in the films by controlling the composition ratios, x, due to the d–π* electronic conjugation.