High contrast and low-driving voltage electrochromic device containing triphenylamine dendritic polymer and zinc hexacyanoferrate

• ZnHCF shows high transparency while exhibiting high charge capacity.
• ECD contained TPA dendritic polymer and ZnHCF was successfully be prepared.
• First-transition EC switching shows a ΔTmax of 60% at 490 nm and stable behavior.
• Narrow potential was required to drive the ECD within the first transition.

A new electrochromic device (ECD), in which poly(N′,Nʺ,N‴-tris[N,N-bis-(4′-diphenylamino-biphenyl-4-yl)phenyl]-1,3,5-benzene-tricarboxamide) (PG1) acted as the electrochromic film and zinc hexacyanoferrate (ZnHCF) as an ion storage material, was proposed. ZnHCF was observed to exhibit high charge capacity while maintaining high transparency when undergoing redox reaction. This ECD shows two-stage electrochromism and both transitions exhibit significant transmittance change (>60% at 490 and 740 nm). Low-driving voltage (from −0.4 to 0.1 V) was also observed when switching in the first transition. This ECD also exhibits a very stable behavior (no significant decay for the transmittance change at 490 nm after 4000 cycles) when operating in the first transition.

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