Super-Resolution Luminescence Microspectroscopy Reveals the Mechanism of Photoinduced Degradation in CH₃NH₃PbI₃ Perovskite Nanocrystals

Summary, in English

Photoinduced degradation of individual methylammonium lead triiodide (MAPbI3) perovskite nanocrystals was studied using super-resolution luminescence microspectroscopy under intense light excitation. The photoluminescence (PL) intensity decrease and blue-shift of the PL spectrum up to 60 nm together with spatial shifts in the emission localization position up to a few hundred nanometers were visualized in real time. PL blinking was found to temporarily suspend the degradation process, indicating that the degradation needs a high concentration of mobile photogenerated charges to occur. We propose that the mechanistic process of degradation occurs as the three-dimensional MAPbI3 crystal structure smoothly collapses to the two-dimensional layered PbI2 structure. The degradation starts locally and then spreads over the whole crystal. The structural collapse is primarily due to migration of methylammonium ions (MA+), which distorts the lattice structure causing alterations to the Pb–I–Pb bond angle and in turn changes the effective band gap.

• Author: Aboma Merdasa; Monojit Bag; Yuxi Tian; Elin Källman; Alexander Dobrovolsky; Ivan Scheblykin
• Department/s: Chemical Physics; NanoLund: Centre for Nanoscience
• Publishing year: 2016-04-22
• Language: English
• Pages: 10711-10719
• Publication/Series: Journal of Physical Chemistry C
• Volume: 120
• Issue: 19
• Links: http://dx.doi.org/10.1021/acs.jpcc.6b03512
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Materials Chemistry; Condensed Matter Physics (including Material Physics, Nano Physics)
• Keywords: perovskite; photo-induced degradation; photophysics; blinking; super-resolution microscopy
• Status: Published
• ISBN/ISSN/Other: ISSN: 1932-7447