Bonding‐Guided Anisotropic Growth of Quasi‐1D M ₂ X ₃ Se ₈ Thermoelectric Nanowires

Abstract Quasi‐1D van der Waals materials have emerged as promising candidates for flexible electronic and thermoelectric applications due to their intrinsic anisotropy, narrow band gaps, and mechanical flexibility. Herein, M ₂ X ₃ Se ₈ ( M = Nb, Ta, X = Pd, Pt) nanowires are studied to understand the bonding‐directed growth mechanism. Bond valence sums and binding energy analyses reveal that weak X 2‐Se2 interactions perpendicular to the c‐axis facilitate anisotropic growth. Integrated Crystal Orbital Hamilton Population calculations show that the Ta─Se bonds in Ta ₂ Pd ₃ Se ₈ possess greater bonding strength along the growth direction compared to the Nb─Se bonds in Nb ₂ Pd ₃ Se ₈ and Nb ₂ Pt ₃ Se ₈ , predicting longer nanowires for Ta ₂ Pd ₃ Se ₈ . Experimental synthesis and SEM length statistics confirm this trend. Thermoelectric measurements confirm n‐type behavior with enhanced power factor in Ta ₂ Pd ₃ Se ₈ . Ta ₂ Pd ₃ Se ₈ also forms centimeter‐long, flexible nanowires via chemical vapor transport. This work demonstrates bond‐guided growth for quasi‐1D M ₂ X ₃ Se ₈ and identifies Ta ₂ Pd ₃ Se ₈ as a leading candidate for flexible thermoelectric devices.