Lambda 950 pka

All solvents were used as purchased from the Tokyo Chemical Industry (Tokyo, Japan) or Fuji Film-Wako Chemicals (Tokyo, Japan). All synthesis procedures for BN1-4 were provided in the previous report (Ando et al., 2019 (link)). Absorption spectra of the samples were measured using an ultraviolet–visible,-near-infrared spectrometer (Lambda 950-PKA, Perkin-Elmer, MA, United States). Fluorescence and phosphorescence spectra were measured using a spectrofluorometer (FP-8600, JASCO International, Japan). The photoluminescence quantum yield (PLQY) was measured using a PLQY measurement system (Quantaurus-QY, Hamamatsu Photonics, Hamamatsu, Japan). The transient PL decay characteristics of BN4 in toluene were recorded by a dynamic range streak camera system (C10910-01, Hamamatsu Photonics, Hamamatsu, Japan) with a third harmonic YAG laser (355 nm, 10 Hz, PL-2250, EKSPLA, Lithuania) as an excitation source. The transient PL emission and PL decay of BN1, 2, 3, and 4 doped in a DPEPO host film were recorded under vacuum with a streak camera (C4334, Hamamatsu Photonics, Hamamatsu, Japan) with a third harmonic YAG laser (266 nm, 10 Hz, LS-2132UTF, LOTIS TII, Belarus) as an excitation source.

UV-vis absorption spectra were recorded using a Perkin-Elmer Lambda 950-PKA instrument. Fluorescence and phosphorescence spectra at RT and 77 K were recorded by an FL980 spectrometer (Edinburgh Instrument) equipped with a gated photomultiplier tube. Transient PL decay profiles, time-resolved emission spectra, and temperature-dependent PL spectra were measured on a FL980 spectrometer (Edinburgh Instrument), excited with a 320 nm laser diode. The transient lifetime measurements were conducted in vacuum. For the temperature-dependence measurement, an Oxford Instruments liquid nitrogen cryostat (Optistat DN) was adopted. PLQYs of films were measured by a calibrated integrating sphere (Edinburgh Instrument) excited at 320 nm in FL980.

UV–vis absorption spectra were recorded using the Perkin‐Elmer Lambda 950‐PKA instrument. Fluorescence and phosphorescence spectra were recorded by a FluoroMax‐4 spectrofluorometer. Transient PL decay spectra were conducted on FLS980 (Edinburgh Instrument), in which the prompt component in the nanosecond scale was measured with a TCSPC laser and the delayed component in microsecond scales was measured with a microsecond flash lamp. Their delayed spectra were measured in FLS980 utilizing a time‐gated controller. Temperature‐dependent PL spectra and transient PL decay spectra of the film samples were also measured on FLS980 equipped with Oxford Instruments nitrogen cryostat (Optistat DN) for temperature control. PLQYs of the films were measured on FLS980 utilizing an integrating sphere, while the PLQYs of the solutions were measured utilizing a QE 2000 quantum efficiency measurement system (Otsuka Electronics). The singlet and triplet energies were calculated using the onset of the emissions (Figure S21, Supporting Information).