Fig. 1. Schematic diagram of three kinds of base-ZGNR coupling devices (the bases are all sandwiched perpendicularly between two infinite N-ZGNR electrodes): (a) the base is parallel to the zigzag edges and the zigzag edges keep perfect in the structures (N-AGNR-I-(a)), (b) the base is parallel to the zigzag edges and the zigzag edges are disconnected in the scattering region (N-AGNR-I-(b)), (c) the base is vertically to the zigzag edges, and the left and right electrodes are non-coplanar (N-AGNR-I-(c)).

Fig. 2. Descriptions of the currents as a function of the applied bias of N-AGNR-I-(j). Purple solid, red solid, dashed, dotted, and dash-dotted curves in panels (a)–(f) correspond to the structures of pristine N-ZGNR, N-ZGNR-A-(j), N-ZGNR-C-(j), N-ZGNR-G-(j), and N-ZGNR-T-(j). Panels (a)–(c) correspond to 4-ZGNR-I-(a), 4-ZGNR-I-(b), and 4-ZGNR-I-(c); Panels (d)–(f) correspond to 5-ZGNR-I-(a), 5-ZGNR-I-(b), and 5-ZGNR-I-(c). The insets in panels (a)–(f) correspond to the rectification ratio RR.

Fig. 3. Panels (a)–(c) [(d)–(f)] describe the electron transmission spectra of 4-ZGNR-I-(a) (4-ZGNR-I-(b)) at bias voltages 0.6 V, 1.0 V, and 1.4 V. Purple solid, red solid, dashed, dotted, and dash-dotted curves in panels (a)–(c) [(d)–(f)] correspond to the structures of pristine 4-ZGNR, 4-ZGNR-A-(a), 4-ZGNR-C-(a), 4-ZGNR-G-(a), and 4-ZGNR-T-(a) (4-ZGNR, 4-ZGNR-A-(b), 4-ZGNR-C-(b), 4-ZGNR-G-(b), and 4-ZGNR-T-(b)). The left and right insets of panels (a) and (b) [(d) and (e)] show the LDOSs of 4-ZGNR-A-(a) and 4-ZGNR-C-(a) (4-ZGNR-A-(b) and 4-ZGNR-C-(b)) at E = 0.

Fig. 4. Panels (a)–(c) [(e)–(g)] describe the electron transmission spectra at bias voltages 0.2 V, 0.4 V, and 0.8 V (at bias −0.2 V, −0.4 V, and −0.8 V). Purple solid and red solid curves in panels (a)–(c) and (e)–(g) correspond to the structures of pristine 4-ZGNR and 4-ZGNR-A-(c). The insets of panels (a)–(b) and (e)–(f) show the LDOSs of 4-ZGNR-A-(c) at E = 0, and The insets of panels (c) and (g) show the LDOSs of 4-ZGNR-A-(c) at E = −0.24 eV. Solid, dashed, and dotted curves in panel (d) [(h)] describe the electron transmission spectra in pristine 4-ZGNR at bias 1.87 V, 4-ZGNR-G-(c) at bias 1.87 V, and 4-ZGNR-G-(c) at bias −1.87 V (pristine 4-ZGNR at bias 1.56 V, 4-ZGNR-T-(c) at bias 1.56 V, and 4-ZGNR-T-(c) at bias −1.56 V).

Fig. 5. Description of the currents as a function of the applied bias of 4-ZGNR-I-(h) and 4-ZGNR-I-(f) in panels (a) and (b). Purple solid, dashed, dotted, and dash-dotted curves in panel (a) correspond to the structures of N-ZGNR-A-(h), N-ZGNR-C-(h), N-ZGNR-G-(h), and N-ZGNR-T-(h). Purple solid, dashed, dotted, and dash-dotted curves in panel (b) correspond to the structures of N-ZGNR-A-(f), N-ZGNR-C-(f), N-ZGNR-G-(f), and N-ZGNR-T-(f). The insets in panels (a)–(b) correspond to the LDOS at E = 0.5 eV.

Fig. 6. Panels (a), (b), (c), and (d) describe the phonon transmission, thermal conductance, Seebeck coefficient, and ZT values of N-ZGNR-A-(i) (i = d and e) at temperature 200 K, respectively. Solid, dashed, dotted, and dash-dotted curves in panels (a), (b), (c), and (d) correspond to 4-ZGNR, 4-ZGNR-A-(d), 4-ZGNR-A-(e), and 5-ZGNR-A-(e). The inset in panel (b) corresponds to the thermal conductance ratio η (T) = k_i/k₀, and the dashed, dotted, and dash-dotted curves correspond to 4-ZGNR-A-(d), 4-ZGNR-A-(e), and 5-ZGNR-A-(e). The inset in panel (c) corresponds to the electron transmission spectra, and the solid, dashed, dotted, and dash-dotted curves correspond to 4-ZGNR, 4-ZGNR-A-(d), 4-ZGNR-A-(e), and 5-ZGNR-A-(e). The inset in panel (d) corresponds to the ZT value of 4-ZGNR-A-(e) at temperature 300 K.