J. W. Blatchford

Alternating‐current light‐emitting devices based on conjugated polymers

Most polymer electroluminescent devices to date are represented as tunnel diodes and operate under direct‐current (dc) driving field. Here we report the fabrication of symmetrically configured alternating‐current (ac) light‐emitting (SCALE) devices based on conjugated polymers. The new devices consist of an emissive polymer layer sandwiched between two redox polymer layers. This configuration enables the SCALE devices to work under both forward and reverse dc bias as well as in ac modes. The nearly ohmic electrode/redox polymer contacts improve the charge injection efficiency significantly and make the SCALE device operation insensitive to electrode work functions. Symmetric operation supports the key role of redox polymer/emissive polymer interface states.

Electronic structure of pyridine‐based polymers

We present the results of semiemiprical quantum chemical calculations on oligomers of poly(p‐pyridyl vinylene) (PPyV) and poly(p‐pyridine) (PPy). The presence of a nitrogen heteroatom in the conjugated backbone of these polymers presents a potentially severe breaking of both spatial and charge‐conjugation symmetry (CCS), and the addition of nonbonding (n) orbitals has potentially major effects on the photophysics of these systems. Geometries are optimized at the PM3 Hartree–Fock level for neutral, singly charged and doubly charged oligomers. We find that the geometric distortions associated with polaron formation are centered on the vinylene linkages in PPyV‐based systems and on the interring bonds in the PPy‐based systems. We discuss the electronic structure at the PM3 level applying configuration interaction between singly excited states (SCI), and we demonstrate that the lowest‐lying (n→π*) states of the ideal polymer chain are well above the lowest (π→π*) states, leading to strong fluorescence in thes...

Exciplex emission in heterojunctions of poly(pyridyl vinylene phenylenevinylene)s and poly(vinyl carbazole)

Abstract We present photoluminescence and electroluminescence spectra of heterojunctions formed from poly(vinyl carbazole) (PVK) and poly(pyridyl vinylene phenylene vinylene) (PPyVPV). Bilayers of PVK and PPyVPV show a photoluminescence peak which cannot be assigned to either the PVK or the PPyVPV layer. Absorption spectra show that the additional feature results from an exciplex at the bilayer interface. The electroluminescence spectrum from the heterojunctions is due to exciplex emission, with internal efficiencies of ~ 0.1–0.5%.

Litho/Design Co-Optimization and Area Scaling for the 22-nm Logic Node

We present a comprehensive study of area scaling for 22nm-logicnode routed metal/via layers as a function of route pitch and patterning strategy in both single-exposure (SE) and doublepatterning (DP) regimes. For each candidate route pitch (8856nm), we determine an optimal illumination scheme and develop layout rules for the metal layers. A perturbative area model is used to approximate the impact of the candidate rule set on area scaling. For the most promising SE case, we apply a novel ‘source/design optimization’ technique to further optimize illumination and rules, wherein we extend the source-mask optimization approach (1) by allowing design rules to vary in the analysis. We demonstrate that the optimal area scaling achievable with DP techniques can be vastly superior to SE, and therefore may justify the associated additional cost per wafer.

Picosecond photoinduced absorption and long-lived effects in polyaniline

Abstract We present results of picosecond photoinduced absorption studies on poly(pernigraniline base) (PNB), the degenerate-ground-state form of polyaniline, and poly(emeraldine base), a nondegenerate form. When pumped at the 2.1 eV absorption edge, both polymers display photoinduced absorption in the 1.3-1.6 eV region due to charged polarons. PNB displays additional absorption at >1.5 eV due to neutral solitons. For each of these polymers, the photogenerated polaron absorption at fixed pump/probe time delay is found to lose oscillator strength with continued exposure to the pump beam, decaying in a stretched-exponential manner over several minutes and saturating at about 10 percent of its initial value. In PNB, the soliton absorption saturates completely and is replaced by a slowly-decaying bleaching signal which is comparable in magnitude. We consider a possible origin of these effects to be buildup of longlived electronic states in the polymers.

Five-layered symmetrically configured ac light-emitting (SCALE) devices and their three-layered variations: use of gold as an electron and hole injection electrode

Symmetrically configured ac light-emitting (SCALE) devices based on conjugated polymers utilizing indium-tin oxide (ITO) and aluminum as electrodes have been demonstrated recently. Here we report the fabrication of SCALE devices using a more stable high workfunction metal, such as gold, as a charge (both electron and hole) injection electrode. Also, a variation of such devices in which the electroluminescent polymer, instead of being separated from the insulating polymer, is dispersed in the insulating polymer to form a unified emitter-insulator is reported. These devices emit light in both forward and reverse dc bias with symmetric current- voltage characteristics. Under low frequency ac (sinusoidal) driving voltage, light pulses with double the driving frequency are observed. A model is proposed to account for the device operation.