Events
Event Overview
Design Principles of Shift Current Photovoltaics
Speaker: Ashley Cook (U Toronto)
Date & Time: May 26, 2016, 2:00 - 3:00
Location: Hennings 304
Local Contact: Marcel Franz
Intended Audience: Graduate
While the basic principles and limitations of conventional solar cells are well understood, relatively little attention has gone toward evaluating and maximizing the potential efficiency of photovoltaic devices based on shift currents. In this talk, we give a brief introduction to the shift current. We discuss its promise as a mechanism for high-performance, low-cost photovoltaics and how it may be of interest to many in the condensed matter physics community. Those focused on low-dimensional systems, non-centrosymmetric materials, polar materials, transition metal oxides, hybrid perovskites, and topologically nontrivial physics may be especially interested.
This talk also intends to encourage searching for high-performance shift current photovoltaics and further understanding the shift current via effective modelling, complementing the work of more established ab initio and experimental communities. To this end, we discuss our recent work, in which a sum rule approach is generalized to enable study of the shift current with tight-binding models. Design principles for optimizing shift currents at photon energies near the band gap are also introduced. Two new classes of shift current photovoltaics are identified based on these methods, ferroelectric polymer films and orthorhombic monochalcogenides, both of which exhibit peak photoresponsivities larger than predictions for previously known photovoltaics of this type. Exploring the phase space of these models, we find photoresponsivities that can exceed 100 mA/W. These results show that considering the microscopic origin of shift current via effective models allows one to improve the possible efficiency of devices using this mechanism and better grasp their potential to compete with conventional solar cells. They also hint at the possible benefits of greater participation of the condensed matter physics community in this topic of research.