We report on the fabrication of low power operated, stretchable array of active-matrix based electrochromic devices (ECDs). ECD consists of poly(3-methylthiophene) and prussian blue grown on indium tin oxide coated polyethylene terephthalate film, and mixed gel electrolyte of acetonitrile, poly(methyl methacrylate), propylene carbonate, and LiClO4. Upon application of a bias voltage at -1, 0, and 1 V, the ECD displays red, green, and blue colors, respectively. For the operation of the ECD, low powers of 373 μW/cm2 at -1.0 V and 378 μW/cm2 at 1.0 V are consumed but with a high coloration efficiency of 201.6 cm2/C at 1.0 V.
On a stretchable Ecoflex substrate, 4x4 array of ECDs with corresponding 4X4 n-type FETs as active-matrix elements for preventing the cross-talk, are integrated using patterned liquid metal, GaInSn interconnections. Such fabricated ECD array exhibits a mechanical stability under biaxial stretching by 30% and bending deformation. Finite element method analysis of the strain distribution also confirms that the strain is only concentrated onto the Ecoflex area between the active devices of ECD and FETs.
This work demonstrates the high potential of our fabricated stretchable ECD array in the application to full-color display associated with stretchable electronics, wearable devices, and electronic skin.