viologen based electrochromic devices reveal that bias induced color change appears due to bias induced change in oxidation state of viologen. The blue color of the device as a result of negative bias is obtained due to presence of viologen frees redical (EV$^{\newmoon +  }$). Raman spectra from the devices under this bias condition confirms the presence of viologen free redical in both the geometries of device. Raman signature corresponding to the free redical is seen on the electrode connected to the negative polarity of the power supply (used to bias the device) whereas EV$^{2+}$ (viologen dication) is present on the other electrode which was connected to the positive polarity. Species on the positive terminal of the device is same as the species present in the whole device in its virgin state. Since the cross bar geometry device is symmetric, it shows color switching between transparent to navy blue aster application of bias irrespective of the polarity. In-situ UV-Vis spectra reveals that the navy blue color of the device under biased condition is not due to increase in the transparency corresponding to blue wavelength but due to suppression of the transparency corresponding to the complementary colors. A 85 % contrast 