Abstract
Mixed tin-lead halide perovskite solar cells have promising power conversion efficiencies, but long-term stability is still a challenge. Herein we examine the stability of a 60:40 tin-lead perovskite to better understand diminished device performance upon thermal treatment, both in ambient and inert atmosphere. Operando X-ray diffraction shows a stable bulk structure of the perovskite absorber, leading to the hypothesis that surface chemistry dominates the degradation mechanism. X-ray photoelectron spectroscopy reveals two new observations post-thermal annealing that accompany previously reported Sn4+ evolution: (i) the formation of I3- intermediates preceding I2 loss at the surface and (ii) evidence of under-coordinated tin and lead surface sites (Snδ<2+ and Pbδ<2+, respectively) in inert and ambient conditions. These two species indicate an activated corrosion (i.e., both oxidation and reduction) process at the surface as a possible chemical pathway for degradation, which is expected to be accelerated under operando voltage and light biases.
Original language | American English |
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Pages (from-to) | 3344-3351 |
Number of pages | 8 |
Journal | ACS Energy Letters |
Volume | 5 |
Issue number | 11 |
DOIs | |
State | Published - 2020 |
Bibliographical note
Publisher Copyright:©
NREL Publication Number
- NREL/JA-5900-78853
Keywords
- corrosion
- degradation
- lead compounds
- lead metallography
- perovskite
- photodegradation
- surface chemistry
- tin compounds
- tin metallography
- X-ray photoelectron spectroscopy