Phase transition kinetics and surface binding states of methylammonium lead iodide perovskite

Abstract

We have presented a detailed analysis of the phase transition kinetics and binding energy states of solution processed methylammonium lead iodide (MAPbI3) thin films prepared at ambient conditions and annealed at different elevated temperatures. It is the processing temperature and environmental conditions that predominantly control the crystal structure and surface morphology of MAPbI3 thin films. The structural transformation from tetragonal to cubic occurs at 60 °C with a 30 minute annealing time while the 10 minute annealed films posses a tetragonal crystal structure. The transformed phase is greatly intact even at the higher annealing temperature of 150 °C and after a time of 2 hours. The charge transfer interaction between the Pb 4f and I 3d oxidation states is quantified using XPS.

Ethylammonium Lead Iodide Formation in MAPbI3 Precursor Solutions by DMF Decomposition and Organic Cation Exchange Reaction

“…Hopefully, some of the conflicts can be neutralized by our recently published work, where we revealed the importance of hydrogen bonding for the perovskite structural stability and discovered the true cause of the irreversible degradation [10]. However, there remains some other substance detected during the synthesis of the CH 3 NH 3 PbI 3 thin film, which has yet to be identified by the perovskite solar cell community, despite the fact that a similar phenomenon was also reported before elsewhere [23,24]. As the impurity could influence the device performance, and thus it calls for a systematic investigation.…”

Magnetic optical rotary dispersion and magnetic circular dichroism in methylammonium lead halide perovskites

“…In particular, the extent of excitonic effects in lead halide perovskites is debated, especially across polycrystalline thin films and macroscopic single crystals 37 . While recent low temperature, high field, and magneto‐optic studies have claimed consistent exciton binding energies across MAPbI 3 crystals and films, such observations might not be valid at room temperature and in the low magnetic field limit 20,38 . Our results suggest that further investigation is needed to understand the fundamental excitonic properties of MAPbI 3 single crystals at room temperature.…”

Scalable Flexible Perovskite Solar Cells Based on a Crystalline and Printable Template with Intelligent Temperature Sensitivity

“…The Pb 4 f 7/2 and Pb 4 f 5/2 peaks (at 138.3 and 143.1 eV, respectively) in the reference perovskite film shifted (≈0.2 eV) to the direction with lower binding energy in the 6OBA‐incorporated perovskite film (Figure S13, Supporting Information). [ 36 ] In addition, the characteristic 1 H NMR peaks of MAPbI 3 shifted to a low field in the 6OBA‐incorporated film, manifesting a deshielding effect (Figure S14, Supporting Information). [ 37–39 ] The deshielding effect on the hydrogen of MA + can enhance the performance of F‐PSCs.…”