Strong temperature-strain coupling in the interface of Sb thin film on flexible PDMS substrate

Two-dimensional (2D) materials on flexible substrates have shown unique applications due to their excellent mechanical related properties. Here, single crystalline, high quality, and continuous 2D antimony (Sb) thin films on SiO₂ and flexible polydimethylsiloxane (PDMS) substrates are prepared by the vapor deposition method. Temperature-dependent Raman spectra of the Sb thin film on PDMS and SiO₂ substrates are studied, which indicates that there is a strong temperature-strain coupling between the Sb thin film and PDMS substrates. In order to further study the coupling interaction, the temperature-dependent phonon frequency is deeply investigated, ranging from 193 K to 393 K. Moreover, the strain-dependent phonon frequency of 2D Sb is calculated by the first-principles method based on density functional theory and compared with experimental results. We find that the biaxial strain in the Sb thin film on the PDMS substrate is about 0.225% for each change in the temperature of 100 K. This provides an effective method to study and control the physical properties of 2D materials.