Device physics of white polymer light-emitting diodes

The charge transport and recombination in white-emitting polymer light- emitting diodes (PLEDs) are studied. The PLED investigated has a single emissive layer consisting of a copolymer in which a green and red dye are incorporated in a blue backbone. From single-carrier devices the effect of the green- and red-emitting dyes on the hole and...

Physics of organic ferroelectric field-effect transistors

Most of the envisaged applications of organic electronics require a nonvolatile memory that can be programmed, erased, and read electrically. Ferroelectric field-effect transistors (FeFET) are especially suitable due to the nondestructive read-out and low power consumption. Here, an analytical model is presented that describes the charge...

Charge transport and recombination in polyspirobifluorene blue light-emitting diodes

The charge transport in blue light-emitting polyspirobifluorene is investigated by both steady-state current-voltage measurements and transient electroluminescence. Both measurement techniques yield consistent results and show that the hole transport is space-charge limited. The electron current is found to be governed by a high intrinsic...

Photoluminescence of conjugated polymer blends at the nanoscale

Here we report on a combined photoluminescence and morphological study of a polymer-polymer blend composed of a copolymer of derivatives of polyspirobifluorene and polyfluorene (PBFF) and a derivative of polyphenylene vinylene (MDMO-PPV). Evidence of partial Förster energy transfer from PBFF to MDMO-PPV is revealed by steady-state and time...

Role of balanced charge carrier transport in low band gap polymer: Fullerene bulk heterojunction solar cells

Lowering of the optical band gap of conjugated polymers in bulk heterojunction solar cells not only leads to an increased absorption but also to an increase of the optimal active layer thickness due to interference effects at longer wavelengths. The increased carrier densities due to the enhanced absorption and thicker active layers make low...

The effect of ketone defects on the charge transport and charge recombination in polyfluorenes

The effect of on-chain ketone defects on the charge transport of the polyfluorene derivative poly(9,9-dioctylfluorene) (PFO) is investigated. Using MoO3 as ohmic hole contact, the hole transport in a pristine PFO diode is observed to be limited by space-charge, whereas fluorenone contaminated PFO (PFO-F) is shown to be trap limited by the...

Field-assisted ionization of molecular doping in conjugated polymers

The field- and temperature dependence of the charge transport in solution-processed poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) doped with tetrafluoro- tetracyanoquinodimethane (F4-TCNQ) is investigated. Conventional charge transport models based on a density- and field-dependent mobility in combination with a constant...

Exciton quenching close to polymer: Vacuum interface of spin-coated films of poly(p-phenylenevinylene) derivative

Polymer-fullerene bilayer heterostructures are suited to study excitonic processes in conjugated polymers. Excitons are efficiently quenched at the polymer-fullerene interface, whereas the polymer-vacuum interface is often considered as an exciton-reflecting interface. Here, we report about efficient exciton quenching close to the polymer-vacuum...

Photoinduced charge and energy transfer in dye-doped conjugated polymers

Conjugated polymer-molecular dye blends of MDMO-PPV (poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene]) and PF1CVTP (poly[9,9-dioctylfluorene-2,7-diyl-alt-2,5-bis(2-thienyl-1-cyanovinyl)-1-(3′,7′-dimethyloctyloxy)-4-methoxybenzene-5″,5″-diyl]) with three dipyrrometheneboron difluoride (bodipy) dyes were studied by (time-resolved)...

Triplet formation from the charge-separated state in blends of MDMO-PPV with cyano-containing acceptor polymers

Polymer blends of MDMO-PPV with three different electron accepting cyano-substituted polymers have been investigated with photoinduced absorption (PIA) spectroscopy. In these blends, an efficient photoinduced charge transfer occurs that quenches the photoluminescence and produces a significant photovoltaic effect when the blends are incorporated...

Photovoltaic properties of a conjugated polymer blend of MDMO-PPV and PCNEPV

Photovoltaic properties of solution-processed semiconducting polymer blends have been studied. It is demonstrated that photoinduced charge transfer occurs in binary mixtures of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly-[oxa-1,4-phenylene-(1-cyano-1,2-vinylene)-(2-methoxy-5-(3, 7-dimethyloctyloxy)-1,4...