Nonlinear terahertz control of the lead halide perovskite lattice

Lead halide perovskites (LHPs) have emerged as an excellent class of semiconductors for next-generation solar cells and optoelectronic devices. Tailoring physical properties by fine-tuning the lattice structures has been explored in these materials by chemical composition or morphology. Nevertheless, its dynamic counterpart, phonon-driven ultrafast material control, as contemporarily harnessed for oxide perovskites, has not yet been established. Here, we use intense THz electric fields to obtain direct lattice control via nonlinear excitation of coherent octahedral twist modes in hybrid CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskites. These Raman-active phonons at 0.9 to 1.3 THz are found to govern the ultrafast THz-induced Kerr effect in the lowtemperature orthorhombic phase and thus dominate the phonon-modulated polarizability with potential implications for dynamic charge carrier screening beyond the Frohlich polaron. Our work opens the door to selective control of LHP's vibrational degrees of freedom governing phase transitions and dynamic disorder.

Automated summary

We use intense THz electric fields to directly control the lattice of hybrid CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskites by nonlinear excitation of octahedral twist modes. Raman-active phonons in the range of 0.9 to 1.3 THz are found to dominate the phonon-modulated polarizability, leading to the ultrafast THz-induced Kerr effect and potential implications for dynamic charge carrier screening beyond the Frohlich polaron. Our work opens up the possibility of selectively controlling the vibrational degrees of freedom in LHPs, which can influence phase transitions and dynamic disorder.