A Topological Principle for Photovoltaics

Explore a groundbreaking lecture on a novel topological principle for photovoltaics presented by Aris Alexandradinata at the PCS Institute for Basic Science. Delve into the concept of maximizing the shift component of bulk photovoltaic current in noncentric semiconductors with wide band gaps to achieve efficient solar cells without inhomogeneous doping. Discover a new class of topological insulators compatible only with polar crystal classes, where the k-dependent electron-hole dipole moment cannot be continuously tuned to zero throughout the Brillouin zone. Learn how averaging the shift vector over high-symmetry cross-sections of the Brillouin zone results in a rational multiple of a Bravais lattice vector parallel to the polar axis. Understand why the frequency-integrated shift conductivity of intrinsically polar insulators significantly exceeds e^3/h^2 and surpasses that of ferroelectric BaTiO3 by at least three orders of magnitude, challenging the notion that small band gaps are necessary for large shift currents in topological materials. This 50-minute talk offers valuable insights into advanced photovoltaic research and its potential implications for solar cell technology.