NGSE5, Day 3: Plenary by Mike McGeehee
In the plenary Prof. McGehee reports on his progress in making metal halide perovskite solar cells stable. In his labs his group has been able to pass the industry standard ALT tests with Perovskites in a device architecture based on a layer stack of Perovskite/Fullerene/ALD SnO/Sputtered ITO. In his view especially the ALD layer is very important to achieve stability.
A second issue Prof. McGeehee is addressing is the reverse biasing of Perovskites, a state that commonly occurs in applications when there is partial shading. Reverse bias is very harmful to PSKs. Part of the reason for this is that PSKs are a form of electrochemical cell, that will lead to reduction of materials and subsequently breakdown.
The McGeehee group has developed quite a bit of understanding of the underlying processes of this breakdown, in part through a custom Drift-Diffusion model that accounts for ion mobility.