Varied π‑Conjugated Extension Directions\nin B←N Coordinated Benzodipyrrolidone (BDP) Polymer Semiconductors:\nEffects on n‑Type Organic Field-Effect Transistors (OFETs)

In\nthe current state of organic semiconductor development, n-type\nsemiconductors are significantly less advanced than their p-type counterparts,\nparticularly in the realm of high-electron-mobility materials, which\nare crucial for high-grade organic field-effect transistors (OFETs)\nin commercial electronics. Over the past few years, the incorporation\nof B←N coordination units has emerged as a promising approach\nto enhancing n-type properties. However, the exploration of polymers\nwith π-conjugated extensions in different directions has been\nlargely overlooked. This study introduces two novel B←N coordinated\nBDP-based polymers, P1 and P2, synthesized with distinct π-conjugated\nextension directions: along the backbone and perpendicular to it,\nrespectively. P1, with its advantages in energy levels, planarity,\ncrystallinity, and backbone transport, demonstrates an electron mobility\nof 1.81 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>, which is more than twice the performance of P2. This achievement\nsets a new benchmark for B←N coordinated n-type OFETs, marking\none of the highest reported electron mobilities to date.