Reduced threshold of optically pumped amplified spontaneous emission and narrow line-width electroluminescence at cutoff wavelength from bilayer organic waveguide devices

Abstract

We present a detailed study of the optically and electrically pumped emission in the BSB-Cz/PVK bilayer waveguide devices. By optical pumping we demonstrate that PVK as a spacer between fluorescent BSB-Cz and ITO electrode allows the significant reduction of the threshold for amplified spontaneous emission (ASE) of BSB-Cz. The simulation provides a better understanding of how the PVK thickness affects the waveguide mode field distribution and hence the ASE threshold of BSB-Cz. On the other hand, the BSB-Cz/PVK bilayer OLED exhibits the external quantum efficiency of >1% and anisotropic electroluminescence with spectrally narrowed edge emission at the cutoff wavelength controlled by the BSB-Cz thickness. When tuning the cutoff wavelength to match the peak gain of BSB-Cz, we demonstrate an intense, particularly narrow edge emission (~5 nm) without obvious degradation of efficiency at a high current density of 1000 mA/cm², suggesting a reliable device performance for high-power applications and further exploration of electrically-pumped ASE.

High-Brightness Blue Polariton Organic Light-Emitting Diodes

“…Its photoluminescence spectrum shows maxima at 448 nm, 470 nm, and 512 nm, which correspond to the vibronic 0−0, 0−1, and 0−2 transitions, respectively. 29,30 Furthermore, pure BSBCz is strongly horizontally oriented when deposited as a thin film, 31,32 which will be beneficial to the outcoupling efficiency of OLEDs based on it and can facilitate efficient strong coupling to vertical cavity modes.…”

“…BSBCz has been shown to exhibit nearly balanced bipolar charge carrier mobility (μ e‑ ≈ 3 × 10 –4 cm 2 /(V s), μ h+ ≈ 7 × 10 –4 cm 2 /(V s)), high photoluminescence quantum efficiency (≈77%), as well as a short fluorescence lifetime (≈1 ns), even in a neat film or when mixed into a host material at high concentration. ,, Due to its strong excitonic absorption, which peaks at around 370 nm, BSBCz is a good candidate for strong light–matter coupling (Figure b). Its photoluminescence spectrum shows maxima at 448 nm, 470 nm, and 512 nm, which correspond to the vibronic 0–0, 0–1, and 0–2 transitions, respectively. , Furthermore, pure BSBCz is strongly horizontally oriented when deposited as a thin film, , which will be beneficial to the outcoupling efficiency of OLEDs based on it and can facilitate efficient strong coupling to vertical cavity modes.…”

Bottom-up honeycomb top layer for light outcoupling enhancement in blue organic light emitting diodes

“…For this study, a benchmark light emitting material i.e. 4,4′ bis(4 (9H carbazol 9 yl)styryl)biphenyl (BsB4) has been selected as the blue fluorescent emitter [56,57]. To examine the light extraction ability of the honeycomb films deposited on the outer side of the glass substrate the following structures represented in Fig.…”

“…To elaborate the electrical model, we took the HOMO/LUMO data from the literature [67,68], as well as the work function of the LiF/Al cathode [66] and the ITO/MoO 3 anode [65]. Electron mobility of BsB 4 is 1.2e 8 cm 2 /Vs [67]. As we could not find data for hole mobility in BsB4, we tested that our results are practically unchanged upon taking a hole mobility between 1e 5 cm 2 /Vs and 1e 8 cm 2 /Vs for BsB 4 (larger than electron's mobility).…”

Asymmetric coupling coefficients induced amplified spontaneous emission in planar coupled waveguides

“…In the past two decades, polymer-based waveguides with optical gain have emerged as cost-effective components in optical networks for short-haul data communication [1][2][3]. A simple waveguide system that constitutes an active polymer layer as core which is surrounded by semicontinuous media are extensively studied with the view of both optical [4][5][6][7][8][9][10][11][12] and electrical excitation [13,14]. When two * Author to whom any correspondence should be addressed.…”