The device model employed to investigate the transport properties of nAGNRs and nZGNRs is illustrated in Figure and 1b respectively, where n defines the number of C-atoms along the width of GNR and dangling bonds are passivated with H-atoms. The device comprises of total 12 and 14 unit cells for AGNR and ZGNR respectively and is divided into three regions: left electrode, right electrode and scattering region as shown by blue vertical lines in Figure . Out of the total unit cells, 4 unit cells are used for semi-infinite left and right electrodes, while rest 8 and 10 unit cells are assigned as scattering region for AGNR and ZGNR respectively. To study the effect of reducing the width of GNR, the width of blue dotted rectangular box in the scattering region is sequentially reduced from infinitely long 13AGNRH (shown with blue dotted box in Figure ) to poly-phenylene chain designated as 3AGNRH (red dotted box in Figure ). Similarly, for ZGNRH, it has been reduced from 12ZGNRH to a polyacene chain designated as 2ZGNRH, shown with blue and red dotted box respectively in Figure .