Non-conjugated Polyelectrolytes Research Articles

Polymer-metal hybrid transparent electrodes for flexible electronics.

Despite nearly two decades of research, the absence of ideal flexible and transparent electrodes has been the largest obstacle in realizing flexible and printable electronics for future technologies. Here we report the fabrication of ‘polymer-metal hybrid electrodes’ with high-performance properties, including a bending radius <1 mm, a visible-range transmittance>95% and a sheet resistance <10 Ω sq−1. These features arise from a surface modification of the plastic substrates using an amine-containing nonconjugated polyelectrolyte, which provides ideal metal-nucleation sites with a surface-density on the atomic scale, in combination with the successive deposition of a facile anti-reflective coating using a conducting polymer. The hybrid electrodes are fully functional as universal electrodes for high-end flexible electronic applications, such as polymer solar cells that exhibit a high power conversion efficiency of 10% and polymer light-emitting diodes that can outperform those based on transparent conducting oxides.

A Depletion‐Free, Ionic, Self‐Assembled Recombination Layer for Tandem Polymer Solar Cells

An innovative method for achieving depletion-free recombination layers (RLs) in inverted tandem polymer solar cells is demonstrated using ionic self-assembly of a cationic non-conjugated polyelectrolyte and an anionic metallic polymer. These RLs form tunnel junctions with different work functions of 5.1 eV and 3.9 eV on each of their surfaces. The tandem solar cells containing these RLs exhibit solar power conversion efficiencies exceeding 8.3%. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Organic Electronics: Electrostatically Self‐Assembled Nonconjugated Polyelectrolytes as an Ideal Interfacial Layer for Inverted Polymer Solar Cells (Adv. Mater. 22/2012)

Organic Electronics: Electrostatically Self‐Assembled Nonconjugated Polyelectrolytes as an Ideal Interfacial Layer for Inverted Polymer Solar Cells (Adv. Mater. 22/2012)

Electrostatically Self‐Assembled Nonconjugated Polyelectrolytes as an Ideal Interfacial Layer for Inverted Polymer Solar Cells

Electrostatically Self‐Assembled Nonconjugated Polyelectrolytes as an Ideal Interfacial Layer for Inverted Polymer Solar Cells

Polyelectrolyte platform for sensitive detection of biological analytes via reversible fluorescence quenching

Non-conjugated polyelectrolytes were used to quench oppositely charged fluorescent dye–ligand conjugate (DLC) molecules by bringing them to the vicinity of the polyelectrolyte backbone to form aggregates and hence quench the dye fluorescence. As target protein molecules are added to the solution, the specific interaction between the DLC and the protein disrupts the aggregate structure, thus recovering the luminescence. The binding of DLC to oppositely charged polyelectrolyte and the disruption of the aggregates are investigated by fluorescence spectroscopy. The static-quenching mechanism is clearly manifested in the Stern–Volmer plots that show the decrease in slope with increasing temperature. This polyelectrolyte-based sensing platform has a sensitivity of <100pM. We also show the selectivity of this platform by comparing the fluorescence recovery between two proteins (avidin and bovine serum albumin) with similar molecular weight. Our results suggest a highly sensitive approach for detecting biological analytes.

Conjugated Polymers as Efficient Fluorescence Quenchers and Their Applications for Bioassays

We have developed a novel approach for simple and convenient detection of ligand−receptor interactions with high sensitivity and selectivity. The method harnesses a reversible fluorescence quenching between nonfluorescent polyelectrolyte quenchers and fluorescent probes tagged to ligands. Formation of more strongly bound ligand−receptor complexes forces the breakup of nonspecific, electrostatic interaction-based quencher/probe pairs to reverse the fluorescence quenching, triggering a fluorescence increase, and providing an off-to-on detection of the ligand/receptor interaction. Although a conjugated polyelectrolyte was used in the study, other nonconjugated polyelectrolyte quenchers are expected to work as well. The method should potentially find a wide variety of applications in several areas, ranging from drug screening, medical diagnostics, and biosensing to assay development.

Förster Energy Transfer Studies of Polyelectrolyte Heterostructures Containing Conjugated Polymers: A Means To Estimate Layer Interpenetration

Using a sequential adsorption process, thin film multilayer assemblies of polymers which photophysically interact via the Forster energy transfer mechanism have been fabricated and characterized in order to determine the level of interpenetration between layers. The assemblies consisted of layers of poly(phenylene vinylene) (PPV) which were separated from layers of a sulfonatopropoxy anion derivatized poly(p-phenylene) [(−)PPP] by nonconjugated polyelectrolyte spacer bilayers. The spacer bilayers were composed of poly(allylamine hydrochloride) (PAH) with a polyanion of either poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), or poly(styrenesulfonate) (PSS). An estimate of the level of interpenetration of the layers was made for each type of spacer bilayer by correlating the relative amount of quenching of the (−)PPP photoluminescence with the measured total thickness of the spacer bilayer(s) utilizing a diffuse layer model which assumed a Gaussian distribution of polymer segments. Using this approac...

Thermally stimulated currents and electrical conduction in self-assembled ultrathin films

Ultrathin films were formed from two types of non-conjugated polyelectrolytes, that is, polyallylamine (PAH) and polystyrensulfonate (PSS) using a self-assembly process and their electrical properties were investigated. Current versus voltage properties of the devices showed hopping conduction. The conduction was considered to be due to the migration of mobile ions in the sample, and that was also supported by temperature and humidity dependence of transient currents. Furthermore, thermally stimulated currents (TSCs) properties also suggested the ionic space charge polarization. Although the origin of mobile ions is not yet clear, the existence of sodium in the films was observed from the electron spectroscopy for the chemical analysis (ESCA). The humidity (i.e. water in the devices) also had a great influence on the electrical properties. The sodium ions and/or oxonium ions in the device are considered mobile ions.

Electroluminescence Studies on Self-Assembled Films of PPV and CdSe Nanoparticles

Electrooptical and structural studies on self-assembled films composed of CdSe nanoparticles, poly(p-phenylene vinylene) (PPV), and different nonconjugated polyelectrolytes are reported. It is demonstrated by optical spectroscopy and X-ray reflectivity measurements that CdSe nanoparticles and PPV can successfully be incorporated into homogeneous ultrathin films by the self-assembly method. The surface roughness obtained from the X-ray measurements is 2.7 and 1.3 nm respectively for CdSe/PAH (PAH, poly(allylamine) hydrochloride) and PSS/PPV (PSS, poly(styrenesulfonic acid)) multilayer films. This allows us to stack a (PSS/PPV)*n film on top of a (CdSe/PAH)*n film to build up well-defined two-layer composite film devices. Electroluminescence studies show that pure (PSS/PPV)*n film devices exhibit green light emission but with a very short lifetime (several seconds) if operated in ambient air. During operation, the PPV emission shifts toward the blue, which indicates that the mean conjugation length of PPV i...