Benign and detrimental chemical decomposition routes depleting methylammonium cation in hybrid perovskites

Juarez-Perez , Emilio J.
Research Network Perovskites for solar energy conversion and optoelectronics (PEROVSKITAS)
Participation type: 
Ponencia plenaria e invitada
Castelló (Spain)

ARAID, Government of Aragon, Zaragoza, Spain Institute of Nanoscience of Aragon (INA), University of Zaragoza, Spain, Campus Río Ebro, Edif. I+D, C/ Mariano Esquillor Gómez, s/n, Zaragoza, 50018, ES
Lead halide based perovskites have emerged as promising active materials for photovoltaic cells. Enormous efforts have been devoted to device fabrication and optimization leading to power conversion efficiencies exceeding 22%, which gives perovskite solar cells the competitive advantage over many other well-known solar technologies. Despite superb efficiencies achieved in laboratory-scale devices, it was soon recognized that long-term stability was rapidly compromised under ambient conditions and such instability could jeopardize the future of perovskite solar cells.
In the present communication, a clear demarcation line between photo- and thermal degradation processes in methylammonium (MA) based perovskite is traced[1-3] including characterization techniques employed identifying decomposition gases released.[4] Based on experimental evidence, a clear distinction between true decomposition reactions and evaporation-like processes suffered by MA is done. The halide effect on stability is discussed in terms of energy barriers during degradation reactions showing a better stability of Br based perovskite ascribed to two aspects: (i) lower Brönsted-Lowry acidity of HBr compared to HI and (ii) higher nucleophilic character of CH3NH2 compared to NH3. Finally, current strategies to overcome the long-term chemical instability in hybrid perovskite are analyzed.


[1] Juarez-Perez, E. J., Hawash, Z., R. Raga, S., Ono, L. K., Qi, Y., "Thermal degradation of CH3NH3PbI3 perovskite into NH3 and CH3I gases observed by coupled thermogravimetry - mass spectrometry analysis" Energy Environ. Sci. 2016, 9, 3406-3410.

[2] García-Fernández, A., Juarez-Perez, E. J., Castro-García, S., Sánchez-Andújar, M., Ono, L. K., Jiang, Y., Qi, Y., "Benchmarking chemical stability of arbitrarily mixed 3D hybrid halide perovskites for solar cell applications" Small Methods 2018, , 1800242.

[3] Juarez-Perez, E. J., Ono, L. K., Maeda, M., Jiang, Y., Hawash, Z., Qi, Y., "Photodecomposition and thermal decomposition in methylammonium halide lead perovskites and inferred design principles to increase photovoltaic device stability" J. Mater. Chem. A 2018, 6, 9604-9612.

[4] Juarez-Perez, E. J., Ono, L. K., Uriarte, I., Cocinero, E. J., Qi, Y., "Degradation Mechanism and Relative Stability of Methylammonium Halide Based Perovskites Analyzed on the Basis of Acid-Base Theory" ACS Appl. Mater. Interfaces 2019, 11, 12586-12593.