• Nicholas, Robin J.
• Brenes, Roberto
• Stranks, Samuel D.
• Savenije, Tom J.
• Maude, Duncan K.
• Bulović, Vladimir
• Hutter, Eline M.
• Plochocka, Paulina
• Osherov, Anna
• Galkowski, Krzysztof

Abstract

<p>Temperature-dependent X-ray diffraction (XRD) was used to study the structural changes around the low-temperature (TP?OP) phase transition of polycrystalline MAPbI₃ perovskite thin films prepared using a lead acetate precursor recipe on silicon substrates. Thin films of the MAPbI3 perovskite were deposited on glass, quartz or silicon substrates by spin-coating a lead acetate-based precursor solution followed by annealing of the films. The orthorhombic-to-tetragonal and vice versa phase transitions were monitored via the XRD method. The diffractograms reveal the structural evolution of the films upon a cooling/heating cycle through the TP?OP phase transition. Here, the films are controllably cooled from room temperature to 100 K and then heated back to 298 K. The diffractograms indicate clear shifts in the peak positions to higher 2θ angles upon cooling followed by a gradual shift toward lower 2θ angles during the heating cycle. Upon heating, the peak character remains OP-dominant until 160 K, when it becomes a mixed phase of both and then a predominantly TP above 170 K. These XRD results suggest that both TP and OP coexist at temperatures around the phase transition. Furthermore, the relative fraction of each phase in the temperature range of 140?160 K is not the same when comparing cooling and heating cycles, as evident from the diffractograms at 160 K.</p>

Topics

• perovskite
• impedance spectroscopy
• phase
• x-ray diffraction
• thin film
• glass
• glass
• phase transition
• Silicon
• annealing