IEEE Journal of Selected Topics in Quantum Electronics

Organic distributed feedback lasers can detect nanoscale materials, and are, therefore, an attractive sensing platform for biological and medical applications. In this paper, we present a model for optimizing such laser sensors, and discuss the advantages of using an organic semiconductor as the laser material in comparison to dyes in a matrix. The structure of the sensor and its operation princip... View full abstract»

We report a novel blue emission triphenylamine substituted arylfluorene (SPhTPA) as organic optical gain medium with low amplified spontaneous emission (ASE) threshold. The optical gain related properties of SPhTPA and its blends with inert polymer, polystyrene (PS), were investigated in detail. This study shows the gain property and photo-stability of SPhTPA have been improved significantly by do... View full abstract»

We demonstrated a significant reduction of amplified spontaneous emission (ASE) threshold for an organic optical gain medium operation on an ITO-coated glass by introducing a solution-processed cellulose acetate (CA) thin film as a space layer between the ITO electrode and the optical gain active layer. Using PFO as an optical gain medium, we observed a 4.4-fold threshold reduction from 140 ;... View full abstract»

We report on the use of oxygen as triplet quencher to reduce singlet-triplet annihilation in light-emitting organic solid films and solvent-free molecular semiconducting liquids. For this purpose, a fluorescent heptafluorene derivative is dispersed either in a wide bandgap 4,4'-Bis (N-carbazolyl)-1,1'-biphenyl (CBP) host or in a solvent-free liquid matrix based on 9-(2-ethylhexyl)carbazole (EHCz).... View full abstract»

This study employs the polyfluorene composite (called Green B) with several colors of quantum dots to generate the high-color-rendering index (CRI) white LEDs. The Green B polymer is a good candidate to manufacture the hybrid w-LED because of its good quantum efficacy. The hybrid w-LEDs are fabricated by the mixing of Green B with yellow quantum dots and red quantum dots or orange quantum dots to ... View full abstract»

In this study, microstructure arrayed films, such as microlens and microprism arrayed sheets, were introduced to the front side of quantum dot light-emitting diodes (QLEDs) to enhance the extraction efficiency of the QLEDs without fabricating complex micro/nano-structures directly on the substrate of the QLEDs. Additionally, the optical properties of the microlens and microprism film-attached QLED... View full abstract»

We performed optical simulations and experiments to investigate the internal optics of graphene anode organic light-emitting diodes (OLEDs). The efficiencies, emission distribution, and spectral characteristics of four-layered graphene anode OLEDs were extracted and compared to those of ITO anode OLEDs. Unlike the case of the ITO anode OLED, the efficiencies and emission distributions of graphene ... View full abstract»

A high-efficiency blue phosphorescence organic lightemitting diode (OLED) with a new ambipolar organic compound, 9-(2-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl)-9H-carba zole (CbzTAZ) as the host, structurally engineered the emitting layer (EML) and electron-transporting layer (ETL) to achieve the great carrier balance in the EML. The chemical structure of CbzTAZ contains an electron-transporting... View full abstract»

We investigate the angle-resolved emission of a multimode organic microcavity in a microscope, setup with a high numerical aperture. In the angle-integrated spectra, we observe the formation of narrow deep minima and maxima typical for Fano-like interference in microcavities. Our experimental angle-resolved transmission and emission spectra agree well with corresponding numerical simulations using... View full abstract»

The realization of high-efficiency organic small molecule: Fullerene solar cells are challenging but become more and more feasible due to the rapid development in donor materials and device fabrication techniques. In the past several years, the optimization in the processing techniques, such as, solvent vapor annealing (SVA), the use of solvent additives had led to superior improvement in the devi... View full abstract»

Recently, plasmonic effects of metal nanostructures have been intensively exploited to enhance the performance of organic solar cells (OSCs). The plasmonic-optical effects of localized surface plasmon resonances, scattering effect and propagating surface plasmon resonances, etc., are well recognized in considerably enhancing the active layer absorption. Besides, the improved electrical properties ... View full abstract»

Developing an organic luminescent solar concentrator (LSC), featuring ultralong lifetime and high transparency simultaneously, is crucial for building-integrated photovoltaic applications, such as solar energy harvesting clear windows. In this paper, a tandem organic LSC is encapsulated and connected with three optically transparent layers, namely an encapsulating epoxy layer and two insulating Si... View full abstract»

Effort to improve the bulk heterojunction organic solar cells' absorption efficiency utilizes tandem structures combining low- and high-bandgap absorbing polymers so that a broader spectrum of sunlight's energy can be used for the photon-to-electron conversion and the thermalization loss of photon energy can be reduced. However, at the intersection of the upper energy level of the high-bandgap pol... View full abstract»

Colloidal quantum-dot-based photovoltaic devices (CQDPVs) were fabricated at room temperature in air atmosphere via a spraying technique. Lead sulfide colloidal quantum dots (CQDs) were utilized for this process and various fabrication conditions such as the spraying pressure, types of ligand molecules, duration of ligand exchange, and the band-gap of the CQDs were investigated in order to optimiz... View full abstract»

Time-resolved spectroscopy is a powerful tool for studying fundamental photophysics in optoelectronic materials on a molecular temporal scale. In this review, we describe transient spectroscopic studies on fundamental photovoltaic conversion processes in polymer solar cells, which consist of a series of conversion processes such as photon absorption, exciton diffusion into a donor/acceptor interfa... View full abstract»

The potential for organic electronic technologies to produce low-cost energy at large scales is often cited as the most attractive feature of these materials. Such aspirations depend on the ability of materials to be printed from solution at high speeds across large areas using roll-to-roll (R2R) processing. However, progressing the technology from the laboratory environment into the industrial ma... View full abstract»

The cheap basis of organic sensors likely to be soon available for large areas (over 25 cm2) opens novel opportunities for flat capture photonic schemes. We investigate one such scheme whereby a thin coverslip-type glass above an organic sensor is used as an illumination medium. To preserve sufficient resolution of the order of 50 μm in spite of the nonimaging optics of considera... View full abstract»

In this paper, conventional transformation optics is applied to design an optical cloak in mid-IR region (5 μm) for TM polarization to conceal cylindrical object using composite optical structures. Effective medium theory in this method will be used. Based on required permittivity and permeability for TM radiation, we approximate the cloak region by a 25 polymeric composite cylindrical laye... View full abstract»

In this paper, we introduce a single-step self-assembling process aimed at forming two-dimensional (2-D) array microstructures made from a nanocomposite polymer layer in which are dispersed CdSe-CdS nanocrystals. The novelty of the process reported here is that it operates simultaneously as a two-fold process where the liquid polymer matrix is self-shaped by electrohydrodynamic pressure as a 2-D a... View full abstract»