Evolution 600

Figure 1 shows the structure of the LEC device (ITO/emission layer/Ag) and the material used in the emission layer. The patterned indium tin oxide (ITO) substrates were cleaned using isopropyl alcohol, acetone, and deionized water sequentially in an ultrasonic bath every 15 min. The cleaned substrates were then dried in an oven at 100 °C for 3 h. The solution material of the emission layer was spin coated on an ITO substrate in a glovebox filled with N₂ gas. The thickness change was conducted by controlling the spin coating speed. When the spin coating speed was 250, 500, 1000, and 2000 RPM, the thickness of the thin film was 260, 150, 120, and 100 nm. After that, Ag with a thickness of 100 nm was deposited under high vacuum conditions (5 × 10⁻⁶ Torr). As shown Figure 1a, our LEC device used electrodes and emission layers without injection or transport layers.
The device characteristics of the device were measured using the Current-Voltage-Luminance (IVL) measurement system (PR-655 and Keithley 2400, LMS, Anyang-si, Korea). The size of the active area in the device was 2.25 mm². The morphological properties were analyzed from the shape and crystal distribution on the surface using an atomic force microscope (XE-100). The UV–Vis spectrum was established at a wavelength of 200–600nm using UV–Visible spectroscopy (Evolution 600, Thermo Scientific, Seoul, Korea).

A test sample for UV/Vis spectroscopy was prepared, as shown in Figure 3a. Transmittance was evaluated in the range of wavelength from 400 nm to 700 nm using an UV/Vis spectrometer (Evolution 600, Thermo Fisher Scientific, Waltham, MA, USA). The backing film was located on the reference cell, and the baseline was calibrated by measuring the transmittance of the backing film without a PSA layer.

Unless otherwise noted, chemical reagents and solvents were purchased from commercial suppliers (Tokyo Chemical Industry, Tokyo, Japan, and Sigma-Aldrich, St. Louis, MO, USA), and used without further purification. The NMR spectra for ¹H and ¹³C were taken on a Bruker DRX 300, and mass spectroscopy samples were observed using a JEOL (JMS-700, JEOL, Tokyo, Japan) mass spectrometer. A UV-visible spectrophotometer (Evolution 600, Thermo scientific, Waltham, MA, USA) was used to obtain the absorption spectra. IR spectra were observed over the range 500–4000 cm⁻¹ using a Thermo scientific Nicolet iS10 infrared spectrometer. The fluorescence spectra were obtained using a RF-5301PC spectrophotometer (Shimadzu, Kyoto, Japan).