Thiazole-Fused Naphthalene Diimide-Based n-Type Conjugated Polymer: Synthesis, Properties, and Applications in Organic Electronics.

Significant progress has been achieved in the development of p-type polymers with high hole mobilities. However, the advancement of n-type polymers has been comparatively slower, and the lack of high-performance electron-deficient materials continues to hinder the progress and practical application of various electronic devices. In this study, a new n-type conjugated polymer, PNDTzI, is synthesized based on a thiazole-fused naphthalene diimide unit. The incorporation of two thiazole rings at the β-position of the naphthalene ring effectively reduced steric hindrance between the naphthalene and thiophene units, resulting in an optimized backbone conformation. Density functional theory (DFT) calculations and cyclic voltammetry measurements show that PNDTzI exhibits a highly planar structure and a relatively deep lowest unoccupied molecular orbital (LUMO) energy level of -3.95 eV, facilitating efficient electron injection and transport. Field-effect transistors (FETs) using PNDTzI as the semiconducting layer exhibited the typical n-type transport characteristics with an electron mobility of up to 0.12 cmVs. Additionally, the thermoelectric performance of the n-doped PNDTzI films is evaluated, and the doped thin film shows a Seebeck coefficient of -354 µV K, and a power factor (PF) of 0.04 µWmK.