Anchoring-Induced Interfacial Stabilization in Triphenylamine-Based Electrochromic Polymers

Interfacial instability between electrochromic polymers and transparent conductive electrodes remains a major challenge for achieving durable electrochromic devices. Herein, two triphenylamine-fluorene conjugated polymers, TFPA and TFPACA, are synthesized by incorporating phosphonic acid or dual phosphonic acid/carboxylic acid anchoring groups into the polymers. This anchoring strategy strengthens polymer/ITO interfacial interactions, enhances film adhesion, suppresses interfacial defects, and promotes more uniform charge injection and extraction during electrochemical operation. Both polymers exhibit reversible electrochromic behavior, while the dual-anchored TFPACA-based devices deliver a high optical contrast (ΔT) of 45.08%, a coloration efficiency (CE) of 559.7 cm2 C-1, and excellent cycling stability, retaining 86% of the initial optical contrast after 3500 switching cycles. Building energy consumption simulations further indicate an annual energy reduction of 103,319.23 kWh, corresponding to a carbon emission reduction of approximately 51.66 kg CO2. These results highlight anchoring-induced interfacial engineering as an effective strategy for developing high-performance and durable electrochromic polymers.