Physics

Improved outcoupling of light into substrate modes of an organic LED (OLED) by an ultra-low index of refraction (n=1.15), porous SiO2 grid (UltraLIG) fabricated using glancing-angle deposition is demonstrated. Outcoupling into the substrate for electrophosphorescent tris(2-phenylpyridine) iridium [Ir(ppy)3]-based OLEDs grown on substrates with the UltraLIG is increased by 48% over a conventional device at a luminance of 100 cd/m^2. With efficient light outcoupling at the substrate–air interface, the UltraLIG devices attain EQE=22.5% and PE=64 lm/W at their peak efciencies, a nearly threefold increase over an analogous conventional OLED.

Enhancement of light outcoupling into substrate modes by a grid of low-refractive-index material embedded into the organic layer of an organic light-emitting device (OLED) is analyzed using full-wave electromagnetic simulations. The low-index grid (LIG) redirects modes normally trapped within the high-index organic and indium tin oxide layers (waveguide modes) into the substrate where they can be further extracted into free space using methods such as microlens arrays or roughened surfaces. This increases the external quantum and power efficiencies without affecting the electroluminescent spectrum. The dependence on grid geometry, dimensions, and refractive index is explored to optimize the structure. Simulations show that up to 50% more light can be extracted from the high-index region using an ultralow-index (n = 1.03) grid than a conventional device, and provided efficient substrate-to-air outcoupling, the external quantum efficiencies of LIG OLEDs can reach >50%.

We demonstrate a white organic light-emitting device where individual red, green, and blue (R, G, and B) phosphorescent organic light-emitting devices are vertically stacked and electrically interconnected by a compound MoO3/Li-doped charge generation layer. For the order of B, G, and R cells positioned relative to the indium tin oxide anode, the device yields a peak total external quantum efficiency (EQE) and power efficiency (PE) of ηext = (36±2)% at a current density of J = 82 μA/cm2 and ηp = 21±1 lm/W at J = 17 μA/cm2, respectively. The EQE and PE of the device roll off to (32±2)% and 13±1 lm/W at 1000 cd/m2, corresponding to J = 2 mA/cm2. At this luminance, the device shows Commission Internationale de L’Eclairage chromaticity coordinates of (0.45, 0.36) and a color rendering index of 63.

We demonstrate suppressed singlet-triplet (S-T) quenching, and hence increased quantum efficiency, in high-brightness fluorescent organic light emitting diodes (OLEDs) by reducing the guest triplet population through the introduction of a triplet manager molecule into the emission layer (EML). As an example, an OLED whose EML consists of the red fluorophore, 4-(dicyanomethylene)-2-methyl-6-julolidyl-9-enyl-4H-pyran doped into the host, tris(8-hydroxyquinoline) Al (Alq3) is blended with the triplet manager, 9,10-di(naphtha-2-yl)anthracene. The manager triplet energy is less than that of the host or dopant, leading to efficient triplet removal from the dopant without affecting the radiative singlet population. Measurements suggest the complete suppression of S-T quenching using the triplet management strategy, leading to >100% increase in the steady-state OLED external quantum efficiency.

Strong coupling between excitons and cavity photon modes results in new eigenstates of the system called microcavity polaritons. Due to its photonic contribution, the effective mass of the polariton is greatly reduced from that of the bare exciton, and the integer-spin polaritons can form a Bose-Einstein condensate (BEC) at higher temperatures than cold atoms or excitons. 1, 2 In the last decade, this has led to extensive work on polariton lasing in both inorganic 3, 4 and organic semiconductors, 5 exhibiting a nonequilibrium form of a BEC. 2 ...

Acrobat PDF (90 KB) * * Note that full-text PDFs from conferences typically contain 1-3 pages of content, some or all of which might be an abstract, summary, or miscellaneous items. ... Please enable Javascript in your browser to view the abstract as intended. ... By doping a molecule with low triplet energy in the active regions of organic light emitting diodes and lasers, we demonstrate suppressed triplet-induced losses, thus overcoming a significant obstacle to electrically pumped organic lasers. ... References are not available for this paper.

The reliability of organic photovoltaic cells (OPVs) has become a focus of research. In this work, the intrinsic degradation mechanism of archetypal subphthalocyanine/fullerene OPVs in the absence of water and oxygen is studied. We focus on the initial burn-in period (\ textless 10h) during which there is no significant change in fill factor or open-circuit voltage, suggesting stable interfacial and bulk morphology.

Abstract: There is disclosed ultrahigh-efficiency single-and multi-junction thin-film solar cells. This disclosure is also directed to a substrate-damage-free epitaxial lift-off (“ELO”) process that employs adhesive-free, reliable and lightweight cold-weld bonding to a substrate, such as bonding to plastic or metal foils shaped into compound parabolic metal foil concentrators.