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

In the current state of organic semiconductor development, n-type semiconductors are significantly less advanced than their p-type counterparts, particularly in the realm of high-electron-mobility materials, which are crucial for high-grade organic field-effect transistors (OFETs) in commercial electronics. Over the past few years, the incorporation of B←N coordination units has emerged as a promising approach to enhancing n-type properties. However, the exploration of polymers with π-conjugated extensions in different directions has been largely overlooked. This study introduces two novel B←N coordinated BDP-based polymers, P1 and P2, synthesized with distinct π-conjugated extension directions: along the backbone and perpendicular to it, respectively. P1, with its advantages in energy levels, planarity, crystallinity, and backbone transport, demonstrates an electron mobility of 1.81 cm2 V–1 s–1, which is more than twice the performance of P2. This achievement sets a new benchmark for B←N coordinated n-type OFETs, marking one of the highest reported electron mobilities to date.