We demonstrate that three Ir(III) complexes used as principal dopants in organic electrophosphorescent diodes have very high photoluminescence quantum efficiency (ηPL) a solid-state film. The green emitting complex, fac-tris(2-phenylpyridinato)iridium(III) [Ir(ppy)3], the red-emitting bis[2-(2′-benzothienyl)pyridinato-N,C3′] (acetylacetonato)iridium(III) [Btp2Ir(acac)], and blue complex bis[(4,6-difluorophenyl)pyridinato-N,C2](picolinato)iridium(III) (FIrpic) were prepared codeposited films...

Abstract The temperature dependence of luminescence from [Cu(dnbp)(DPEPhos)]BF 4 (dnbp = 2,9‐di‐n‐butylphenanthroline, DPEPhos bis[2‐(diphenylphosphino)phenyl]ether) in a poly(methyl methacrylate) (PMMA) film indicates the presence long‐life green emission arising two thermally equilibrated charge transfer (CT) excited states and one non‐equilibrated triplet ligand center ( 3 LC) state. At room temperature, lower CT state is found to be predominantly populated state, zero‐zero energy this...

Abstract In this study, we investigate the lasing properties of 4,4′-bis[( N -carbazole)styryl]biphenyl thin films under electrical pumping. The electroluminescent devices incorporate a mixed-order distributed feedback SiO 2 grating into an organic light-emitting diode structure and emit blue lasing. results provide indication by direct injection current film through selection high-gain semiconductor showing clear separation wavelength from significant triplet polaron absorption design...

Enhanced electroluminescence efficiency is achieved in organic light-emitting diodes through delayed fluorescence of the exciplex state formed between 4,4′,4′′-tris[3-methylphenyl(phenyl)amino]-triphenylamine (m-MTDATA) as an electron-donating material and 2,8-bis(diphenylphosphoryl)dibenzo-[b,d]thiophene (PPT) electron-accepting material. The devices exhibited maximum external quantum power efficiencies 10.0% 47.0 lm/W, respectively.

Abstract Triplet–triplet upconversion, in which two triplet excitons are converted to one singlet exciton, is a well-known approach exceed the limit of electroluminescence quantum efficiency conventional fluorescence-based organic light-emitting diodes. Considering spin multiplicity pairs, upconversion usually limited 20%. Although this can be exceeded when energy pair lower than that second excited state, such as for rubrene, it generally difficult engineer levels higher states. Here, we...

Abstract Recently, there has been intense interest in pure organic room‐temperature phosphorescence (ORTP) from cocrystals composed of 1,4‐diiodotetrafluorobenzene (DITFB) and a variety polycyclic aromatic hydrocarbons (PAHs) or their derivatives. To expand the possibility halogen bonding‐based cocrystals, relationship between crystal packing motifs ORTP characteristics binary DITFB PAHs phenanthrene (Phen), chrysene (Chry), pyrene (Pyr), respectively, is investigated. The σ‐hole···π...

To understand confinement of the triplet exciton Ir(ppy)3 by hole-transport layers, we compared energy-dissipative processes which is doped into 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4′-bis [N-(p-tolyl)-N- phenyl-amino]biphenyl (TPD), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), and 4,4′-N,N′-dicarbazole-biphenyl hosts. Significant energy transfer from levels α-NPD was observed. In case TPD host, however, partial This result suggests both forward backward to...

This paper reports on novel electron transport materials, 1,3,5-triazine derivatives (TRZ), which have been useful in high-efficiency electrophosphorescent (EP) organic light-emitting diodes (OLEDs). We synthesized four 2,4,6-tris(diarylamino)-1,3,5-triazine (TRZ1−TRZ4) that had electron-donating substituents and examined their OLED characteristics. Of these, we found TRZ 2, 3, 4 function as a host for tris(2-phenylpyridine)iridium (Ir(ppy)3) and, particular,...

The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting distributed feedback lasers operating quasi-continuous-wave regime at 80 MHz as well under long-pulse photoexcitation 30 ms. This outstanding performance was achieved using an thin film with high optical gain,...

Abstract Long‐lived triplet excitons on organic molecules easily deactivate at room temperature because of the presence thermally activated nonradiative pathways. This study demonstrates long‐lived phosphorescence resulting from suppression deactivation in conventional semiconducting host–guest systems. The pathway strongly depends energy gap between guest emitting and host matrices. required to confine (≈0.5 eV) is much larger than that systems for phosphorescent emitters. By effectively...

Abstract There is increasing interest in thermally activated delayed fluorescence (TADF) materials, and to understand its mechanism the excited state dynamics. Recent challenges include color purity, efficient deep‐blue emission, fast exciton decay lifetimes, high reverse intersystem crossing rates ( k RISC ), low‐efficiency roll‐off organic light‐emitting diodes (OLEDs), long device lifetimes. Here, a series of compounds having benzonitrile carbazole rings are examined, that provide...

Abstract Multi‐resonance emitters (MREs) are a promising candidate for fulfilling the harsh requirements of display applications due to their unique photophysical properties. Recently, MREs have been widely used as terminal emitter in hyperfluorescence organic light‐emitting diodes (HF‐OLEDs); however, since always thermally activated delayed fluorescence (TADF)‐active, possessing long triplet lifetimes millisecond order, they result severe chemical degradation. Instead shortening lifetime...

We examined the amplified spontaneous emission (ASE) characteristics of fluorescent styrylbenzene derivatives doped into a 4,4′-di(N-carbazolyl)biphenyl (CBP) host. In particular, 4,4′-bis[(N-carbazole)styryl]biphenyl (BSB-Cz) demonstrated an extremely low ASE threshold Eth=0.32±0.05μJ∕cm2. observed that 6 wt %-BSB-Cz:CBP film has ultimate photoluminescence (PL) quantum efficiency ϕPL=100% and short transient lifetime τf=1.0±0.1ns, leading to large radiative decay rate kr=1×109s−1....

Organic light-emitting diodes containing a liquid emitting layer that exhibit improved external electroluminescence quantum efficiency (ΦEL) and maximum luminance are presented. Doping the with an electrolyte significantly decreases turn-on voltage for electroluminescence. Insertion of TiO2 hole-blocking between indium tin oxide cathode improves ΦEL. Detailed facts importance to specialist readers published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

Abstract Large external quantum efficiency rolloff at high current densities in organic light-emitting diodes (OLEDs) is frequently caused by the quenching of radiative singlet excitons long-lived triplet [singlet–triplet annihilation (STA)]. In this study, we adopted a scavenging strategy to overcome aforementioned STA issue. To construct model system for scavenging, selected 2,6-dicyano-1,1-diphenyl-λ 5 σ 4 -phosphinine (DCNP) as emitter and 4,4′-bis[( N -carbazole)styryl]biphenyl (BSBCz)...

This work investigates the feasibility of using low-dimensional perovskites for electrically driven lasers given current status perovskite light-emitting diodes and optically pumped lasers. In our progress toward lasers, we performed a variety measurements on bulk films to give baseline expectations. included measurement amplified spontaneous emission, lasing, near-infrared operated at low high density. We considered power density thresholds needed emission lasing compared this speculate...

Fast emission and high color purity are essential characteristics of modern opto-electronic devices, such as organic light emitting diodes (OLEDs). These properties currently not met by the latest generation thermally activated delayed fluorescence (TADF) emitters. Here, we present an approach, called "hot exciplexes" that enables access to both attributes at same time. Hot exciplexes produced coupling facing donor acceptor moieties anthracene bridge, yielding exciplex with large T

Abstract Hexacarbazolylbenzene (6CzPh), which is benzene substituted by six carbazole rings, a simple and attractive compound. Despite the success of wide variety derivatives in organic light‐emitting diodes (OLEDs), 6CzPh has not received attention so far. Here, excellent performances are revealed as host material OLEDs regarding conventional materials. Various strategies implemented to improve performance OLEDs, e.g., triplet utilization thermally activated delayed fluorescence (TADF)...

ABSTRACT Organic lasers hold great promise for enabling a new class of future optoelectronics. Consequently, the development organic semiconductors as gain media has recently been subject significant interest. The molecular design principle based on Einstein coefficients validated achieving high gain, with para ‐phenylene‐vinylene scaffolds recognized one most crucial frameworks. In this study, we develop stilbene tetramer derivative, QSBCz, which significantly increased conjugation compared...

Abstract A strategy for designing highly efficient thermally activated delayed fluorescence (TADF) emitters was reported. TADF with donor–acceptor–donor (D–A–D)-type structures showed because of their small singlet–triplet energy gap and large oscillator strength. An organic light-emitting diode containing a D–A–D-type emitter, cis-BOX2, exhibited high external electroluminescence quantum efficiency 17.6%.