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Overall performance of a polythiophene-ethyl viologen-based solid state electrochromic device has been improved by doping with multi-walled carbon nanotubes (MWCNTs) to exploit its ballistic transport capabilities. The finished hybrid (organic–inorganic) device is free from liquid electrolyte and shows the most efficient color switching with a very small bias and high color contrast while switching between magenta and blue color states. The MWCNTs have been synthesized using the simple pyrolysis method and doped in the viologen containing layer after proper characterization using x-ray diffraction, electron microscopy, and Raman spectroscopy. In situ UV-Vis spectroscopy has been used to quantify the performance of the device that works on the mutual redox-based mechanism of viologen-polythiophene layers. In situ Raman microscopy and spectroscopy have been used to establish the working mechanism duly validated by electrical I-V characteristics of the device. The simple doping process makes the device the most efficient one in the family of polythiophene-based devices. Overall, a liquid electrolyte less, power efficient solid state electrochromic device with a switching time of 1s/0.5 s, a coloration efficiency of 401 cm2/C, a contrast ratio of 79%, and a stability of more than 100 cycles has been achieved.

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Excitation wavelength-dependent Raman spectroscopy has been carried out to study electron–phonon interaction (Fano resonance) in multi-layered bulk 2H–MoS2 nano-flakes. The electron–phonon coupling is proposed to be caused due to interaction between energy of an excitonic quasi-electronic continuum and the discrete one phonon, first-order Raman modes of MoS2. It is proposed that an asymmetrically broadened Raman line shape obtained by 633 nm laser excitation is due to electron–phonon interaction whose electronic continuum is provided by the well-known A and B excitons. Typical wavelength-dependent Raman line shape has been observed, which validates and quantifies the Fano interaction present in the samples. The experimentally obtained Raman scattering data show very good agreement with the theoretical Fano–Raman line-shape functions and help in estimating the coupling strength. Values of the electron–phonon interaction parameter obtained, through line-shape fitting, for the two excitation wavelengths have been compared and shown to have generic Fano-type dependence on the excitation wavelength.