Regensburg 2016 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 80: Hybrid and Perovskite Photovoltaics IV (Joint session of CPP, DF, DS and HL, organized by HL)
HL 80.5: Talk
Thursday, March 10, 2016, 15:45–16:00, H2
Water infiltration in methylammonium lead iodide: fast and inconspicuous — •Christian Mueller1,2,3, Bernd Epding2,3, Tim Helder2,3, Michael Sendner2,3, Annemarie Pucci2,3, Wolfgang Kowalsky1,2,3, and Robert Lovrincic1,3 — 1IHF, TU Braunschweig, Germany — 2KIP, Universität Heidelberg, Germany — 3InnovationLab, Heidelberg, Germany
Extensive research efforts over the last few years led to a significant increase in power conversion efficiency of organometal-halide perovskite (such as CH3NH3PbI3) solar cells up to over 20%. However, our understanding of physical/chemical processes in the material lags behind device progress. For instance, the impact of water on CH3NH3PbI3-based devices, despite being well documented, is still not well understood and as such remains controversial.
Herein we use IR spectroscopy in controlled atmosphere to demonstrate that water infiltration into CH3NH3PbI3 occurs much faster and at much lower humidity than previously thought. We show that the exposure of CH3NH3PbI3 to ambient environment leads to an increase of the photocurrent by more than one order of magnitude in lateral devices. Based on transient photocurrent measurements we speculate that the effect is associated with enhanced proton conduction when light is combined with water and oxygen exposure. Our results suggest that water infiltration plays an important role in the optoelectronic properties of CH3NH3PbI3 based devices, well beyond the known water triggered degradation processes[1].
[1] C. Mueller et al., Chem. Mater., 27 (22), p. 7835-7841, 2015