Lts350

The
thermal behavior of samples was characterized using a Leica DM4500
polarizing optical microscope with ×5, ×10, ×20, and
×40 objectives, a Linkam LTS350 heating stage, a CI94 temperature
controller, and a LN2 cooling system. A small amount of the sample
was placed atop a glass microscope slide and covered with a thin cover
glass. POM analyses were performed using three heating–cooling
cycles: first, a heating–cooling cycle to allow the mixing
of components and the potential kinetically trapped states to transition
to their thermodynamic equivalents. The thermotropic behavior was
studied during the second heating–cooling cycle, after which
the samples were allowed to stand at room temperature to study the
metastable phases.

5 nm Cr and 20 nm Au layers were sequentially deposited on perovskite by thermal evaporation. The channel was defined by an Al wire with diameter of 20 μm serving as shadow mask. The samples were loaded on Linkam LTS350 stage purged with dry nitrogen. DC bias was applied, and current was measured at dark using Keithley 4200-SCS parameter analyzer with 4200-PA remote preamplifier. The voltage was turned on after device initialization and turned off as the ion accumulation was saturated, while the current over time was monitored. The samples were relaxed over 30 min after each test till they recovered from the polarized state.

Ionic transport properties were studied using
a HF2IS impedance
spectroscope (Zurich Instruments). The samples were measured in MicruX
ED-IDE1-Au-interdigitated electrodes (averaged cell constant 0.0276
cm^–1 from the manufacturer) that were glued onto
microscope slides with copper wires directly soldered onto the electrode
cells. A small amount of sample was placed on the electrode, and the
sample was heated up to its flowing state to fill the cell. The filled
sample cell was dried in a vacuum oven overnight at 25–40 °C
prior to measurement. At the start of the measurement, the cell was
heated to 150 °C and stabilized for 20 min. The ionic transport
measurements were then performed during cooling scans from 150 to
0 °C at a rate of 1 °C min^–1, and the
equilibration time was 3 min at the measurement temperature to ensure
a thermal equilibrium. A Linkam LTS350 heating plate, a CI94 temperature
controller, and a LN2 cooling system were used. In the EIS measurement,
a 4-terminal measurement setup with an AC excitation of 100 mV was
applied, and the impedance spectroscopy was performed over the 10
MHz to 10 Hz frequency range. The analysis of EIS data was performed
by using ZView software (Scribner Associates). Additional information
on the EIS can be found in Supporting Information Section S7.

The cell is composed of two glass substrates coated with indium tin oxide (ITO), which serve as the transparent electrode of active area 5 × 5 mm². The alignment layers PI-2555 coated on the surface of ITO were rubbed to provide a planar alignment. The temperature of the cell is controlled with a Linkam LTS350 hot stage and a Linkam TMS94 controller. The AC voltage is applied using a waveform generator (Stanford Research Systems, Model DS345) and an amplifier (Krohn-hite Corporation, Model 7602).

To investigate environment dependence of transport mechanisms, impedance spectroscopy (IS) measurements were performed on the device using a Zahner IM6 electrochemical workstation. To avoid the physical or chemical damage‐induced degradation in the device, Au plated and spring loaded round pogo pins on a PCB substrate were used for reliable electrical contact. The device was sealed inside a chamber (Linkam LTS350). For initial measurement in dark condition, N₂ gas was purged into the chamber overnight. The impedance spectra was checked constantly and the time‐ and environmental‐dependent impedance responses were measured within 1 h. The data point was captured every 2 min during the measurements. For environmentally dependent transport mechanisms under illumination, the measurements were performed under 1 Sun illumination using a Newport solar simulator. Impedance spectroscopy was recorded inside the sealed chamber under different gaseous conditions at a constant flow rate of around 100 mL min⁻¹. The light illumination time was limited to 20 min as continuous illumination causes significantly excessive degradation of the perovskite thin films.