Electrochromism of dinitrobenzoyl-derivatised polypyrrole films deposited on ITO/glass electrodes

Poly[(R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate] films of various thicknesses were galvanostatically deposited on ITO/glass electrodes using different deposition charges (Qdep), and their electrochromic properties were investigated. Depending on the Qdep employed, the polymeric films presented green–yellow or green–brown colours in the reduced state (λmax at 350 nm and shoulder at 390 nm) and a blue–grey colour in the oxidised state (λmax at 460 nm) with high absorption in the near infrared region (λmax > 800 nm). Whilst films deposited with a Qdep of 40 mC cm−2 presented the highest chromatic contrast (20%), films with a Qdep of 50 mC cm−2 exhibited greater stability to redox cycling (ca. 350 cycles), high coulombic efficiency (>73%) and good optical memory in the reduced state (E = 0.0 V).