Fig. 3: Environmental robustness of n-PBDF EC electrodes under weathering conditions.

a Interior view of the accelerated weathering test chamber, showing 12 samples coated with USSC-assisted n-PBDF films of two different thicknesses (d ~ 90 and 150 nm), positioned facing toward a Xenon lamp light without additional surface encapsulation. Accelerated weathering tests were conducted continuously for >768 h (32 days) under 1000 W/m² light intensity, 50% RH, and a chamber temperature of 65 °C. b UV-Vis-NIR absorbance spectra (λ = 350–1800 nm) of 90 nm n-PBDF films, analyzed to track changes in absorbance peaks immediately after weathering exposure (day 0 samples exposed to ambient conditions for the same duration) (measured at least 3 points for each exposed sample). c Operational cycling stability tests for electrochemical switching behavior of 90 nm n-PBDF films at λ = 750 nm, evaluating weathering robustness and electrochemical durability. d UV-Vis-NIR absorbance spectra of 150 nm n-PBDF films, consistent with (b), performed after weathering exposure (measured at least 3 points for each exposed sample). e Electrochemical stability tests of 150 nm n-PBDF films at λ = 550 nm, conducted under conditions identical to those in (c).