Abstract
The sensitivity of organic–inorganic perovskites to environmental
factors remains a major barrier for these materials to become
commercially viable for photovoltaic applications. In this work, the
degradation of formamidinium lead iodide (FAPbI3) perovskite
in a moist environment is systematically investigated. It is shown that
the level of relative humidity (RH) is important for the onset of
degradation processes. Below 30% RH, the black phase of the FAPbI3 perovskite shows excellent phase stability over 90 d. Once the RH reaches 50%, degradation of the FAPbI3
perovskite occurs rapidly. Results from a Kelvin probe force microscopy
study reveal that the formation of nonperovskite phases initiates at
the grain boundaries and the phase transition proceeds toward the grain
interiors. Also, ion migration along the grain boundaries is greatly
enhanced upon degradation. A post‐thermal treatment (PTT) that removes
chemical residues at the grain boundaries which effectively slows the
degradation process is developed. Finally, it is demonstrated that the
PTT process improves the performance and stability of the final device.
Original language | English |
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Article number | 1705363 |
Number of pages | 8 |
Journal | Advanced Functional Materials |
Volume | 28 |
Issue number | 11 |
DOIs | |
Publication status | Published - 14 Mar 2018 |
Externally published | Yes |
Keywords
- degradation
- formamidinium
- humidity
- moisture stability
- perovskite
- solar cells