Alternative splicing engineering modulation of thermal/electrical transmission properties in low-dimensional nanodevices based on five-carbon ring structures

Alternative splicing engineering is a potential strategy to improve the thermoelectric conversion efficiency of low-dimensional nanodevices. The unique thermal/electrical transport properties of 5-carbon ring-based structures can significantly improve thermoelectric performance. The thermoelectric properties of three carbon nanomaterials and devices containing five-carbon ring structures, namely, penta-graphene (PG), penta-octa-penta-graphene (POPG) and Θ-graphene (ΘG), were investigated using density functional theory and non-equilibrium Green's function methods. The results demonstrated that the folded structure of PG gave rise to ring-like electrical transport properties, which greatly reduced effective conductance. POPG exhibited smooth charge transport behavior without scattering loops, leading to relatively higher conductance compared to PG. Meanwhile, embedded 8-carbon ring structures effectively flattened the folded structure of PG and significantly reduced vertical oscillation behavior, resulting in an increase in thermal conductance. For ΘG, the addition of distorted 6-carbon ring structures excited reverse charge transport paths, resulting in lower conductance compared to POPG. The splicing geometry between the 5-carbon ring and 6-carbon ring structure disrupted the original grain boundaries, leading to enhanced phonon scattering and more localized vibrational modes. As a result, ΘG achieved a <i>ZT</i> value of 0.54 near the Fermi energy level at room temperature (300 K).