Polyacetylene PA is a conjugated polymer with alternating single and double carbon-carbon bonds along its backbone. Its electronic properties are derived from the delocalization of -electrons across the conjugated system. The key electronic properties of polyacetylene include:1. Conductivity: Pristine polyacetylene is a semiconductor with a bandgap of around 1.5-2.0 eV. However, upon doping with electron donors n-doping or acceptors p-doping , its conductivity can be significantly increased, making it a conducting polymer. The conductivity of doped polyacetylene can reach up to 10^5 S/cm, which is comparable to that of some metals.2. Optical properties: Due to its conjugated structure, polyacetylene exhibits strong absorption in the UV-visible region, with a characteristic peak around 400-700 nm. This absorption is attributed to the -* electronic transitions within the polymer.3. Electroluminescence: Polyacetylene can emit light when an electric field is applied, making it a potential candidate for organic light-emitting diodes OLEDs .The conjugation length, which refers to the number of consecutive double bonds in the polymer chain, plays a crucial role in determining the electronic properties of polyacetylene. As the conjugation length increases:1. Bandgap: The bandgap of the polymer decreases, leading to a redshift in the absorption spectrum. This is because the energy levels of the and * orbitals become closer as the conjugation length increases, resulting in a smaller energy difference between them.2. Conductivity: The conductivity of the polymer increases with increasing conjugation length. This is because the delocalization of the -electrons across the conjugated system enhances the charge transport properties of the polymer.3. Electroluminescence: The emission wavelength of the polymer shifts to longer wavelengths redshift with increasing conjugation length, as the energy difference between the excited and ground states decreases.In summary, the electronic properties of polyacetylene, such as conductivity, optical properties, and electroluminescence, are strongly influenced by the conjugation length in the polymer. Longer conjugation lengths generally result in smaller bandgaps, higher conductivity, and redshifted optical and electroluminescent properties.