Fls980 spectrofluorometer

Photophysical studies were performed in a solution as well as for emissive layers. All compounds were diluted in chlorobenzene. Thin films of PVK + TADF + Ir blends were prepared on quartz substrates by means of spin-coating. Absorption spectra were detected by a Cary 5000 (Varian Inc.) spectrometer (Palo Alto, CA, USA). The emission spectra were recorded on an Edinburgh Instruments FLS980 spectrofluorometer (Livingston, UK) equipped with an integrating sphere used to determine the photoluminescence quantum yield.
Samples of thick layers (few µm), required for spectrally resolved thermoluminescence (SRTL) experiments, were prepared by drop-casting and spin-coating from chlorobenzene solutions onto aluminum substrates. The samples for SRTL studies were placed in the vacuum chamber on a thermostated holder and covered by a sapphire plate. After sample photoexcitation at 15 K by pulsed nitrogen laser (λ = 337 nm) (PTI, model GL–3300T), the thermoluminescence (TL) measurements were carried out in the temperature range of 20–300 K with a heating rate of 7 K/min. Sample thermoluminescence was recorded by a detection system contained an optical collector, an optical-fiber, a Micro HR Imaging Spectrograph and a CCD 3500 camera (Horriba Jobin–Yvon).

The shape and size of the prepared FNs and FNs-Ca(II) were characterized by transmission electron microscopy (TEM) using a JEM-2100 from JEOL Ltd. (Tokyo, Japan). A Lambda 35 spectrophotometer (PerkinElmer, Waltham, MA, USA) was used for the analysis of the ultraviolet-visible (UV-Vis) spectra of FNs and FNs-Ca(II). Fluorescence spectra were analysed by a F-2700 fluorescence spectrometer (Hitachi, Tokyo, Japan). An FLS 980-spectrofluorometer from Edinburgh Instruments (Edinburgh, UK) was used to measure lifetime with a 320 nm laser as the excitation source. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and zeta potential analysis were conducted using previously reported methods [15 (link)]. The microstructure and local element composition of the FNs and FNs-Ca(II) were characterized by a JSM-7800F scanning electron microscope from JEOL Ltd. (Tokyo, Japan). The ¹H NMR spectra were obtained using a Bruker AV-400 analyser (Daltonics, Germany) with dimethyl-d₆ sulfoxide as the solvent.

The current–luminance–voltage characteristics were measured by using a computer-controlled source meter (Keithley 2400) equipped with a light intensity meter LS-110 under ambient atmosphere without encapsulation. The EL spectra were measured by a Spectrascan PR650 spectrophotometer. The EQEs were calculated from the luminance, current density, and EL spectrum, assuming a Lambertian distribution. The photophysical properties, including UV/vis absorption, photoluminescence (PL), and excitation spectra were measured by a Shimadzu UV-2600 spectrophotometer, and an Edinburgh Instruments FLS 980 spectro-fluorometer. Additionally, the PL transient decay curves of the films were performed on Quantaurus-Tau fluorescence lifetime measurement system (C11367-03, Hamamatsu Photonics Co.). All the results of devices were measured in the forward-viewing direction and all the measurements were carried out under an ambient atmosphere without encapsulation.

The X-ray powder diffraction (XRPD) patterns of the BYF:Yb³⁺,Tm³⁺ phosphors were recorded using a Bruker D8 Advance X-ray diffractometer in the 2θ ranging from 10 to 70^o with X-ray wavelength (λ) of 1.54 Å. The scanning electron microscope (SEM) images were obtained on a JSM-7800 F JEOL field emission scanning electron microscope (FE-SEM). The UCL spectra and the UC decay curves were recorded on a Edinburgh FLS 980 spectrofluorometer. The Commission Internationale de L’Eclairage (CIE) color coordinates were plotted using the Osram-Sylvania color calculator software. The temperature dependent UCL spectra were recorded using Horiba Jobin Yvon iHR320 Fully Automated Imaging Spectrometer. A 980 nm continuous-wave (CW) laser diode was used for pumping the phosphors while recording the UCL spectra, whereas a pulsed 980 nm laser was used for recording the UC decay curves.