Monitoring thermal evolutions of 2D layered semiconductor/polymer heterostructure with ultrafast photoacoustic spectroscopy

Utilizing 2D layered semiconductor as ultrafast photoacoustic transducer, we all-optically generate and track the propagation of picosecond acoustic pulses in 2D layered semiconductor/PMMA thin-film heterostructure via femtosecond laser pump-probe. By varying the environmental temperatures and the incident direction of pump laser pulse, the acoustic velocity of PMMA thin-film has been in situ monitored. The glass transition temperature of PMMA has been measured. Our work provides an all-optical means to noninvasively evaluate thermal responses of polymer thin-films, which are important for studies of thermal interface materials and thermal management of microelectronic devices.