Extended Data Fig. 1: On-surface synthesis of the pentacene polymers on different substrates after annealing at 430 K.

a, Chemical sketch of the precursor molecule 4BrPn. b,c, Large-area and high-resolution STM images of 3a-EBPP on the Ag(111) surface. In b, the directions of 3a-EBPP are indicated by white arrows. d, High-resolution STM image of 3a-EBPP on Ag(111) acquired with a Br-functionalized tip, showing an angle of approximately 14° between 3a-EBPP and the [1\(\bar{1}\)0] direction of the Ag(111) surface, as marked by the white lines. The DFT-optimized structural model is superimposed on the part of the STM image on the right of 3a-EBPP on Ag(111). e,f, Large-area and high-resolution STM images of 5a-EBPP on the Ag(100) surface, and g−i, 1a-EBPP on the Au(111) surface. In e, 5a-EBPP followed the two perpendicular high-symmetry directions on Ag(100). In g, 1a-EBPP formed domains randomly distributed on Au(111). In i, few polymer chains were confined by the herringbone reconstructions on Au(111). Imaging parameters: b, sample bias V_s = 1.0 V, tunnelling current I_t = 10 pA; c, V_s = 1.0 V, I_t = 100 pA; d, V_s = 0.2 V, I_t = 100 pA. e, V_s = 1.0 V, I_t = 10 pA; f, V_s = 0.25 V, I_t = 50 pA; g,h, V_s = 1.0 V, I_t = 50 pA; i, V_s = 1.0 V, I_t = 100 pA.