Pyrimido[4,5-g]quinazoline-4,9-dione as a new building block for constructing polymer semiconductors with high sensitivity to acids and hole transport performance in organic thin film transistors

Abstract

Pyrimido[4,5-g]quinazoline-4,9-dione (PQ) was used for the first time as a building block for π-conjugated polymer semiconductors. Copolymers of PQ and bithiophene showed dramatic bathochromic shifts in their absorption spectra in the presence of protonic (acetic acid and trifluoroacetic acid) and Lewis (BBr₃) acids, resulting from the strong interaction of the basic 1,6-nitrogen atoms in the PQ unit with the acid. These polymers exhibited characteristic p-type semiconductor performance with hole mobilities of up to 6.4 × 10⁻³ cm² V⁻¹ s⁻¹ in organic thin-film transistors (OTFTs). The potential bioactivity, high sensitivity to acids, and good field effect transistor performance of these PQ-based polymers will enable their application for bio- and chemo-sensors.