The low dielectric constant (epsilon(r)-3-4) for semiconducting polymers has been a major cause for their poor performance compared with the inorganic semiconductors, which possess high dielectric constants above 10. This study aimed to increase the electronic/atomic dielectric constant at high frequencies (i.e., epsilon(r infinity)) for semiconducting polymers. A new design strategy was proposed based on the electric field-induced tautomeric structures in conjugated fluorescein. To achieve this goal, fluorescein monopotassium salt-containing random copolymers were synthesized with 50 and 75 mol.% functionality. To reduce the strong electrostatic attraction between the K+ cation and the phenolate anion, 18-crown-6 ether was complexed with K+ in the fluorescein copolymers. A relatively high epsilon(r infinity) of similar to 5.5 and high electron mobility of 0.153 cm(2)/(V.s) were achieved for the 75 mol.% fluorescein K+/18C6 copolymer. The high electron mobility could be attributed to the relatively high static dielectric constant (epsilon(rs) similar to 9 at 1 Hz) of the sample. The fluorescein monopotassium salt copolymers behaved as n-type semiconductors with an optical band gap around 2.26 eV. (C) 2017 Elsevier Ltd. All rights reserved.