Precision Graphene Nanoribbon Heterojunctions by Chain‐Growth Polymerization
Jin‐Jiang Zhang, Kun Liu, Yao Xiao, Xiuling Yu, Li Huang, Hong‐Jun Gao, Ji Ma, Xinliang Feng
Abstract
Abstract Graphene nanoribbons (GNRs) are considered promising candidates for next‐generation nanoelectronics. In particular, GNR heterojunctions have received considerable attention due to their exotic topological electronic phases at the heterointerface. However, strategies for their precision synthesis remain at a nascent stage. Here, we report a novel chain‐growth polymerization strategy that allows for constructing GNR heterojunction with N=9 armchair and chevron GNRs segments ( 9‐AGNR/cGNR ). The synthesis involves a controlled Suzuki–Miyaura catalyst‐transfer polymerization (SCTP) between 2‐(6′‐bromo‐4,4′′‐ditetradecyl‐[1,1′:2′,1′′‐terphenyl]‐3′‐yl) boronic ester ( M1 ) and 2‐(7‐bromo‐9,12‐diphenyl‐10,11‐bis(4‐tetradecylphenyl)‐triphenylene‐2‐yl) boronic ester ( M2 ), followed by the Scholl reaction of the obtained block copolymer ( poly‐M1/M2 ) with controlled M n (18 kDa) and narrow Đ (1.45). NMR and SEC analysis of poly‐M1/M2 confirm the successful block copolymerization. The solution‐mediated cyclodehydrogenation of poly‐M1/M2 toward 9‐AGNR/cGNR is unambiguously validated by FT‐IR, Raman, and UV/Vis spectroscopies. Moreover, we also demonstrate the on‐surface formation of pristine 9‐AGNR/cGNR from the unsubstituted copolymer precursor, which is unambiguously characterized by scanning tunneling microscopy (STM).