Pls 340

The transient PL decay characteristics were measured at room temperature under a nitrogen atmosphere using a fluorescence spectrometer (PicoQuant, FluoTime 300) based on time‐correlated single photon counting (PicoQuant, PicoHarp 300). A pulsed LED (PicoQuant, PLS 340) with an excitation wavelength of 340 nm and a single photon sensitive photomultiplier tube (PicoQuant, PMA‐C) were used. PLQY was measured at room temperature under a nitrogen atmosphere using an absolute PLQY measurement system (Quantaurus‐QY, Hamamatsu). The PL stability test and comparison between the as‐deposited and 3‐h UV‐laser‐exposed films was performed using a He‐Cd laser (KIMMON KOHA, IK3202R‐D) at 3.5 mW with an excitation wavelength of 325 nm. The films for the PL stability test were glass‐encapsulated in a nitrogen‐filled glove box after vacuum deposition. The angle‐dependent PL was measured using a continuous wave laser (325 nm, Melles Griot). The incident angle of the excitation source was fixed at 45°. The angle dependent PL spectra of P‐polarized light were detected using charge‐coupled device (MAYA 2000, Ocean Optics).

Samples were fabricated by thermal deposition for 50-nm-thick film on fused silica substrates under a high vacuum of 10⁻⁸ Torr. The four Ir(III) complexes were doped at a 2 wt% level in a DP-BCZ:PTZP-PCZ host. PL spectra and PL quantum yield of the film samples were measured using Quantaurus-QY absolute PL quantum yield spectrometer (C11347-11, Hamamatsu) and excitation wavelength of 340 nm was used. Time‐resolved PL characteristics for decay time of the Ir(III) complexes were measured using time-correlated single photon counting (TCSPC) setup (Fluotime 300, PicoQuant GmbH). The samples were excited by a pulsed LED (PLS 340, PicoQuant GmbH, 0.25 MHz repetition rate at 340 nm). Angle-dependent PL spectra for calculation of transition dipole moment orientation was measured by Luxol-OLED Analyzer (CoCoLink Korea). The basic principle of this experimental equipment and the measuring method of the angle-dependent PL spectra follow the standard protocol reported previously^{6 (link),23 (link)}. The horizontal transition dipole moment was calculated using the associated fitting software.