and 68 % variation in color has been observed in the device

Acknowledgements {#acknowledgements .unnumbered}
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Authors acknowledge financial support from Department of Science and Technology (DST), Govt. of India. Authors thank Professor R.L. McCreery (NINT, University of Alberta, Canada) for providing gold electrodes and Professor A. Subrahmanyam (IIT Madras, India) for providing ITO electrodes. Authors are thankful to Dr. V. Sathe (UGC-DAE CSR, Indore, India) for Raman measurements. Authors are also thankful to MHRD, Govt. of India for providing fellowships.

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