Yi Jin, Aixi Zhang, Sarah E Wolf, Shivajee Govind, Alex R Moore, Mikhail Zhernenkov, Guillaume Freychet, Ahmad Arabi Shamsabadi, Zahra Fakhraai

Enhanced surface mobility enables rapid equilibration of vapor-deposited glasses toward the supercooled liquid (SCL). We demonstrate that thin films of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine molecular glass, when vapor deposited below a certain temperature, can access a high-density supercooled liquid (HD-SCL) state through a liquid–liquid phase transition ∼35 K below the nominal glass transition temperature of ordinary SCL. The HD-SCL phase transforms into the ordinary SCL when the thickness is increased above 60 nm, demonstrating that HD-SCL is only thermodynamically favored in thin films. These results provide a recipe for accessing kinetically inaccessible regions in the energy landscape, which are critical for understanding the glass transition phenomenon. High-density stable glass states that can resist crystallization and dewetting is also important in various applications.