Flsp920 spectrometer

The concentrations of 1 used in all photophysical measurements were ca. 5 × 10⁻⁶ M in hexane while those used for the emission spectra have a maximum absorbance less than 0.2 to avoid re-absorption. Absorption spectra were recorded on an Agilent 8453 diode-array UV-Vis spectrophotometer. The emission and excitation spectra were recorded using an Edinburgh Instruments FLSP 920 spectrometer equipped with double monochromators for both excitation and emission, operating in right angle geometry mode. The fluorescence quantum yields were measured using a calibrated integrating sphere (150 mm inner diameter). Lifetime measurements were conducted using the time-correlated single-photon counting method (TCSPC) on the FLSP 920 spectrometer equipped with a high-speed photomultiplier tube positioned after a single emission monochromator. Decays were recorded to 10 000 counts in the peak channel with a record length of at least 1000 channels. The quality of all decay fits was judged to be satisfactory, based on the calculated values of the reduced χ² and Durbin–Watson parameters and visual inspection of the weighted and autocorrelated residuals. The lifetimes of 1 in polar solvents were not recorded as the emissions were too weak. All absorption and emission spectra were recorded in standard quartz cuvettes (1 cm × 1 cm) under argon.

Fourier transform infrared (FT-IR) spectroscopy measurements were conducted on a Fourier transform infrared spectrometer (model: IRPrestige-21, range 4000–1000 cm⁻¹). Ultraviolet-visible (UV-vis) absorption measurements were measured on a Lamba 35 spectrophotometer (Perkin-Elmer, Waltham, MA, USA). The X-ray diffraction (XRD) patterns of the films were obtained by a Bruker D8 ADVANCE X-ray diffractometer (Bruker Corp, Berlin, Germany) under the operation conditions of 40 kV and 40 mA. The morphology of perovskite films was obtained by field emission scanning electron microscopy (FESEM, S4800 microscope, Hitachi Ltd., Tokyo, Japan). The transient-state photoluminescence (PL) was measure by FLSP920 spectrometer (Edinburgh Instruments Ltd., Livingston, UK). H nuclear magnetic resonance (NMR) spectra were collected by using Bruker DELL PC1 equipment. X-ray photoelectron spectroscopy (XPS) was studied using a PHI Quantera SXM (ULVAC-PHI Inc., Tokyo, Japan). The current density-voltage (J-V) curves of the devices were measured by a Keithley 2400 Source Meter under an illumination of 1 sun (100 mW/cm² AM 1.5 G, generated by a solar simulator Oriel Sol3A, Newport Corp., Irvine, CA, USA), which was calibrated with a standard Si photodiode. The active area was 0.096 cm².

Fluorescence lifetime measurements were performed on a Horiba Delta Flex time-correlated single photon counting (TCSPC) instrument. A 560 nm nano-LED with a pulse repetition rate of 1 MHz was used as the light source. The instrument response function (IRF) was collected using a scatterer (Ludox AS40 colloidal silica). Fluorescence lifetime (λ_exc = 560 nm) and gated emission was measured on FLSP920 spectrometer, Edinburgh Instruments equipped with a micro flash lamp (µF2) set-up. From the measured decay traces, the data were fitted with a multi-exponential decay, and χ² was less than 1.1.

Powder X-ray diffraction (XRD) was performed on a Rigaku Smartlab diffractometer with Cu Kα radiation at a scanning rate of 10° min⁻¹. Scanning electron microscope (SEM, FEI Quanta 400F) and transmission electron microscope (TEM, FEI Tecnai G2 F30) were employed for the observation of the morphology. Energy dispersive X-ray spectroscopy (EDS) data were obtained using the SEM equipped with the energy dispersive X-ray spectrometer. TEM images, high-resolution TEM (HRTEM) images and selected-area electron diffraction (SAED) patterns were performed at an accelerating voltage of 300 kV. Fourier transform infrared (FTIR) spectra were obtained in transmission mode on a Bruker Equinox 55 FTIR spectrometer with the samples sandwiched between two KBr plates. Photoluminescence excitation and emission spectra were recorded on an Edinburgh FLSP920 spectrometer equipped with a 980 nm diode laser, a 450 W continuous xenon lamp and a 60 W microsecond flash lamp as excitation sources and a R928 red-sensitive photomultiplier tube as detector. The samples were annealed at 500 °C for 1 h prior to upconversion luminescence measurements. All the measurements were performed at room temperature except for the thermometric upconversion photoluminescence.