Lead halide perovskite (LHP) semiconductors emerged as an excellent material platform for next-generation solar cells and optoelectronic devices, but the microscopic origin of their surprising optoelectronic properties, such as long charge-carrier lifetimes and long diffusion lengths, continues to be debated.  These LHP properties are typically tailored by fine-tuning the lattice structure through modifications in chemical composition or morphology. Phonon-driven ultrafast material control, representing the dynamic counterpart to chemical engineering, has nevertheless been mostly elusive.
In a new experimental work recently published in Science Advances, the THz Structural Dynamics group [more...]

Absorption of light in a molecular system typically leads to formation of a correlated electron-hole pair with zero spin, called singlet exciton. If energetically allowed, this singlet exciton may eventually transform into two triplet excitons (with spin 1 each), thereby doubling the number of excited charge carriers. Singlet fission may therefore boost photovoltaic efficiency. The primary step of singlet fission is the ultrafast creation of a correlated triplet pair. Whereas several mechanisms have [more...]