Degradation of CH3NH3PbI3 perovskite due to soft x-ray irradiation as analyzed by an x-ray photoelectron spectroscopy time-dependent measurement method

Abstract

The effects of soft X-ray exposure on structures of CH3NH3PbI3 perovskite were investigated using an X-ray photoelectron spectroscopy (XPS) time-dependent measurement method. A crystalline sample was fabricated with the inverse-temperature crystallization method. The time evolutions of the core-level and valence-band spectra were recorded to determine the compositional ratios and valence band electronic structure of the sample, respectively. In addition, first-principles calculations were conducted to evaluate the valence band XPS spectra. The in situ XPS analysis combined with theoretical calculations demonstrated a degradation of the surface of CH3NH3PbI3 perovskite into PbI2 owing to the evaporation of methylammonium iodide.

Photoelectron spectroscopy on single crystals of organic semiconductors: experimental electronic band structure for optoelectronic properties

“…However, exploration into the electronic band structures of the single crystal halide perovskites by photoemission measurements entails several technical hurdles. For instance, irradiation by high energy photons causes decomposition of the halide perovskite, 194,195 which is common to or even severer than the cases of the single crystal organic semiconductors. Another problem which is not the case for the aforementioned organic semiconductors arises when the three-dimensional (3-D) electronic bands are projected on the 2-D SBZ.…”

Organohalide Lead Perovskites: More Stable than Glass under Gamma‐Ray Radiation

“…Less than a handful of studies have been performed to reveal the effects of proton, electron, and X‐ray irradiation on perovskite so far . Miyazawa et al irradiated perovskite solar cells with 1 MeV electrons and found that the devices retained 93% of their peak performance after irradiation with a fluence of 1 × 10 16 cm −2 .…”

“…indicated a decrease in short‐circuit current density ( J SC ) by 20% for perovskite solar cells exposed to a proton dose of 1 × 10 13 p cm −2 . The perovskite self‐healed with recovery on fill factor (FF) and open‐circuit voltage ( V OC ) after the proton irradiation terminated . The effects of soft X‐ray exposure on uncovered perovskites were investigated by Motoki et al who reported that soft X‐ray irradiation resulted in the evaporation of perovskite surface with residual elements in the form of crystalline PbI 2 .…”

Exciton-Dominated Core-Level Absorption Spectra of Hybrid Organic–Inorganic Lead Halide Perovskites

“…Additional calculations (details reported inFig. S3in the SI) rule out effects due to a phase transition in the perovskite sample, as well as to the presence of metallic elemental Pb, which can be formed upon X-ray illumination, as reported in the recent literature [27][28][29]. X-ray transitions ascribed to Pb-SO 4 and Pb-O bonds are reported to be in this spectral range, 38 however, hard X-ray photoemission data (not shown) does not show any evidence for the presence of either sulfur and/or Pb-O at the surface of the studied samples.…”