Density- and adhesion-controlled ZnO nanorod arrays on the ITO flexible substrates and their electrochromic performance

We report large-scale density- and adhesion-controlled ZnO nanorod arrays (NRs) directly grown on flexible ITO/PET substrates and have studied their absorption capability to viologen molecules and electrochromic performance. The density can be readily controlled by adjusting the thickness of pre-preparated ZnO seed layers. And the adhesion property of the ZnO NRs to substrates can be controlled by different methods of pre-preparation ZnO seed layer. The effect indicates that the ZnO NRs using sputtering-prepared seed layers show superior adhesion property to substrate and resistance capacity to ultrasonicating and bending when compared with the spin-coated method. Moreover, it has been found that the ZnO NRs, with optimum density and occupied space ratio (OSR) (density, similar to 3.34 x 10(9) rods cm(-2); diameter, similar to 140 nm; and OSR, similar to 52%), demonstrate optimal absorption capability to viologen molecules and excellent electrochromic performance. (C) 2010 Elsevier B.V. All rights reserved.