solely by the presence of various electronic equipment's and gadgets. [1][2][3][4] However, as everything comes at the expense of something, the world right now is clearly heading toward some serious shortage of very essential commodities. In order to resonate with the current demand of the society, the major issue at hand that needs to be addressed is the energy crisis we are facing right now. Although, a lot of work is currently going in the industrial front, a good understanding about materials and composites is required for not only making energy storage/conversion, but also energy saving. [5][6][7][8][9] Electrochromic Device (ECD) is one such apparatus that can potentially reduce the energy requirement in buildings, air crafts, automobiles etc., in form of temperature regulators. [10] The basic mechanism of ECDs that includes visible optical changes occurring due to application of some amount of bias is basically driven by redox reactions happening at individual electrodes. [11][12][13] Compatible materials are then chosen and used in a sandwiched manner along with a suitable electrolyte to obtain a final ready-to-use device. [14][15][16] Ever since the birth of Electrochromism by Deb [17,18] a lot of progress in terms of basic parameters like switching speeds, contrast ratio, coloration efficiency etc., has been achieved. Transition Metal Oxides (TMOs like WO 3 ), [19] various polymers (Polythiophene etc) [20,21] metal complexes (like Prussian blue, etc.), [22] and metallo-supramolecular polymers [23] are the materials that act as active layer in an ECD. It is important to mention that when these materials are used in isolation, the devices have little practical application. As a consequence, a device needs to be designed appropriately for optimized operation. Choosing more than one layer has helped in not only improving the device performance, but also in getting multiple color switching. This design, like all others, come with certain constraints that limits the versatility of a device leaving a room for improvement in terms of enhancement of para meters. [10,[24][25][26] Newer ways need to be explored so that a versatile device that can operate with low power consumption, multiple wavelengths and comes with a possibility of integrated in the form of flexible device, can be fabricated.Fundamental applications of ECD such as usage in smart windows of buildings, aircrafts etc., require them to switch Search for a versatile flexible all-organic liquid electrolyte-less solid-state electrochromic device continues. In this quest, a polyaniline-Viologen-(PANI-EV)-based electrochromic device has been reported and designed based on the complementary redox behavior and easy processibility. Electrochromic electrodes are first individually characterized before the device fabrication, to check their compatibility. The polyaniline electrode is electrodeposited and characterized using scanning electron microscopy and Raman techniques followed by bias dependent absorbance measurements to understand its color switching c...
