Molecular engineering stabilizes the commensurate charge density wave state in 1T-TaS2/arginine hybrid superlattices.

The commensurate charge density wave (CCDW) phase in 1T-TaS2 is a prototypical correlated state tied to diverse emergent quantum phenomena. However, its stability is intrinsically limited to cryogenic temperatures. Tailoring correlated electronic states and stabilizing the CCDW phase at room temperature offer new opportunities to investigate and control emergent phenomena under ambient conditions. Here we report a molecular engineering strategy to modulate the charge density wave (CDW) phases in 1T-TaS2/arginine hybrid superlattices. We show that the intercalated arginine molecules exhibit strong non-covalent interactions with the 1T-TaS2 atomic layers, effectively modulating the correlated electronic phase and increasing the CCDW stabilization temperature to 330 K. In contrast, other weakly interacting amino acids produce a less pronounced modulation of the CDW phase transitions. Computational modelling reveals that arginine molecules reshape the CDW energy landscape, enhancing both the thermodynamic stability and kinetic robustness against thermal fluctuations. These findings establish a versatile molecular engineering strategy for tailoring correlated states and electronic orders in van der Waals materials.