Zn2+ assisted co-construction of polyaniline electrochromic device with enhanced infrared modulation

Polyaniline (PANI) is a promising electrochromic (EC) material for adaptive camouflage due to its reversible infrared (IR) emissivity regulation via electrochemical redox processes under electrical stimulation. Nevertheless, structural instability originating from chain conformation degradation during prolonged electrochemical cycling, coupled with restricted polaron delocalization that impedes charge carrier mobility in π-conjugated systems, impose fundamental limitations on IR emissivity regulation, compromising operational durability and emissivity modulation efficiency. Constructing metal ion ligand coordination networks within PANI is a viable strategy for the simultaneous enhancement of optoelectronic performance and structural stability. Capitalizing on this coordination chemistry paradigm, a co-doping strategy combining protonic acid and zinc ion (Zn 2+ ) was developed to fabricate a high-performance PANI-based EC device. The optimized device exhibited an exceptional emissivity modulation amplitude (Δε = 0.65) within 8-14 μm while maintaining 98% emissivity modulation retention after continuous electrochemical switching over 1000 cycles. The results show that co-doping effectively enhances electron delocalization and polaron density in PANI chains. Moreover, the intra- and inter-chain coordination of Zn 2+ with PANI strengthens their interaction, thus improving the IR emissivity modulation range and electrochemical stability.