Polymeric electrochromic devices (ECDs) have found a wide applicability in eyewear, architectural windows, automotive mirrors, aircraft, color changing fabrics and display panels, owing to their high optical contrast, fast response time, and the color multitude achievable via polymer structure modification. Although most ECDs are built on glass support, many encourage the use of plastics as lightweight, flexible and inexpensive substrate materials. Polycarbonate (PC) has attracted particular attention due to its high strength, impact resistance and thermal stability. However, most colored substrate will not transmit UV light, and many grades of transparent plastics contain additives such as UV inhibitors that can prevent curing of gel electrolyte. The addition of thermal or “visible” light curing initiators allowed the ability to cure through UV blocked substrates. Herein, we present a facile method to prepare in-situ solid state gel electrolyte on polycarbonate substrates using a long wavelength photoinitiator (&gt;350nm). Curing kinetics monitoring and characterization were studied by FT-IR and performances were compared among a selected choice of thermal and photo-initiators. Additional surface pre-treatments on Indium Tin Oxide (ITO) coated plastic substrate were used to promote better gel adhesion and electrochromic film quality. Parameters including the types of thermal and photo-initiator, initiator concentration, cross-linker concentration, solvent to polymer ratio, curing condition, gel thickness and ITO surface treatment methods were studied to maximize the performance of ECDs fabricated via in situ method. The optimized electrochromic gel system exhibits high photopic contrast (&gt;50%), fast switching speed (1-3s) and good film quality using poly(2,2 dimethyl-3,4-propylenedioxythiophene) (PProDOT-Me<sub>2</sub>) as the standard electrochromic material. Large area electrochromic visors (5.25’’×11’’) were successfully fabricated on polycarbonate substrate to demonstrate potential for commercial applications.

Optimization of electrochromics on polycarbonate substrates: Use of thermal and long wavelength photo-initiators

253rd National Meeting (2017)

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