Topo-photovoltaics

In non-centrosymmetric materials, light induces real-space shifts of quasiparticles which result in a photovoltaic current. Such shifts arise from all dynamical, far-from-equilibrium, kinetic processes, including photo-excitation, intraband relaxation and interband recombination. These shifts are enhanced by the twisting of electronic wavefunctions in momentum space; such twisting is characterized by the well-known intra-band Berry phase and the less-known inter-band Berry phase. Wave-function-enhanced photovoltaic currents can be utilized as an unprecedented phenomenological framework to faithfully diagnose topological materials, as I will exemplify with the 3D polar semiconductor BiTeI.