•  Stability is calculated by comparing energy of the bulk Perovskite to that of the PbI2 precipitate and salt (using Abinit code)

•  The formability of the new perovskite is checked by using the Goldschmidt tolerance factor (favourable structures are 0.76<t<1.13)[6]

•  The band structures were calculated using Wien2k code

•  The synthesis is done by mixing the solutions of Pb(NO)3 and excess of (CH3NH3)I[3] •  Addition of water to the perovskites results in decomposition as shown below[4]

•  Current methods protect the Perovskite with polymer coating[5] •  Our approach to resolve this issue is to modify the material itself

Enhanced Chemical Stability of Halide Perovskite Photovoltaics

E. Tenuta and O. Rubel

Thanks goes to Dr. Yurij Mozharivskyj, Dr. Emily Cranston and Dr. David Brock for their help on the finer points of chemistry

Introduction & Background

Method

Results and Discussion

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Motivation •  Improved stability via dissociation •  Reasonable, but not perfect band

gaps •  Consistent valence and

conduction band shapes •  Interesting result of S-N

interactions

Conclusion and Future Work

References

•  New emerging photovoltaic material (CH3NH3)PbI3in the Perovskite form ABX3

•  Perovskite has shown impressive increases in efficiency in the past 3 years

•  Known for high charge carrier mobilities, high efficiency and other favorable photovoltaic properties[1] [2] •  Even though the LCOE for photovoltaic systems have dropped

exponentially since the 70’s the initial cost is still high enough to deter people from investing

•  The Perovskite material can be solution processed instead of the conventional lithographic etchants on ultra thin wafers, this could reduce the cost of production even further[1]

•  Manipulation of the cation shows a direct link to both the stability and the band structures of the material

•  The secret to the stability of the Perovskite is not is the extra coatings needed to protect the material but within the structure of the material itself

•  The next step is to create a process for the synthesis of the material, along with creating the

actual material

CH3NH3+ S2N+ SF3

+ SeF3+

[1] You, J. ACS Nano. 2014, 8(2), 1674-1680 [2] Snaith H.J. Phys. Chem. Let.. 2013, 4, 3626-3630 [3] Vincent, B.R. Can. J. Chem. 1987, 65 1042-1046 [4] Niu,G. J. Mater. Chem. A, 2015, 3, 8970-8980 [5] Yang, J. ACS Nano. 2015, 9(2), 1955-1963 [6] Kim, H. J. Phys. Chem. 2014, 118, 5615-5625