Current-Induced Joule Heating and Electrical Field Effects in Low Temperature Measurements on TIPS Pentacene Thin Film Transistors

The channel temperature (Tch) of solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS pentacene) thin film transistors (TFTs) is closely monitored in real time during current–voltage (I–V) measurements carried out in a He exchange gas cryostat at various base temperatures (Tb) between 300 K and 20 K. This is done using a...

Quasi-one dimensional in-plane conductivity in filamentary films of PEDOT:PSS

The mechanism and magnitude of the in-plane conductivity of poly(3,4-ethy-lenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films is determined using temperature dependent conductivity measurements for various PEDOT:PSS weight ratios with and without a high boiling solvent (HBS). Without the HBS the in-plane conductivity of PEDOT:PSS...

The curious out-of-plane conductivity of PEDOT:PSS

For its application as transparent conductor in light-emitting diodes and photovoltaic cells, both the in-plane and out-of-plane conductivity of PEDOT:PSS are important. However, studies into the conductivity of PEDOT:PSS rarely address the out-of-plane conductivity and those that do, report widely varying results. Here a systematic study of the...

Carrier-density dependence of the hole mobility in doped and undoped regioregular poly(3-hexylthiophene)

We investigate the mobility of poly(3-hexylthiophene) (P3HT) over a carrier-density range from 1015 to 1020cm-3. Hole-only diodes were used for densities below 1016cm-3 and field-effect transistors were used for carrier densities higher than 1018cm-3. To fill the gap, intermediate densities were probed using chemically doped Schottky diodes and...

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...

Gate-bias assisted charge injection in organic field-effect transistors

The charge injection barriers in organic field-effect transistors (OFETs) seem to be far less critical as compared to organic light-emitting diodes (OLEDs). Counter intuitively, we show that the origin is image-force lowering of the barrier due to the gate bias at the source contact, although the corresponding gate field is perpendicular to the...

The operational mechanism of ferroelectric-driven organic resistive switches

The availability of a reliable memory element is crucial for the fabrication of 'plastic' logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field modulates the charge injection from a metallic...

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...

In situ neutron depth profiling: A powerful method to probe lithium transport in micro-batteries

In situ neutron depth profiling (NDP) offers the possibility to observe lithium transport inside micro-batteries during battery operation. It is demonstrated that NDP results are consistent with the results of electrochemical measurements, and that the use of an enriched6LiCoO2 cathode offers more insight in transport processes occurring inside...

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...

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...

Effect of n-type doping on the hole transport in poly(p-phenylene vinylene)

N-type doping of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) with decamethylcobaltocene (DMC) strongly improves the electron transport due to filling of the electron traps. Unexpectedly, the n-type doping simultaneously suppresses the hole transport in MEH-PPV. We demonstrate that this strong reduction of the hole...

Universal scaling of the charge transport in large-area molecular junctions

Charge transport through alkanes and para-phenylene oligomers is investigated in large-area molecular junctions. The molecules are self-assembled in a monolayer and contacted with a top electrode consisting of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonic acid) (PEDOT:PSS). The complete set of J(V,T) characteristics of both saturated...

Substituted polyfluorene-based hole transport layer with tunable solubility

We report on the synthesis and electrical characterization of polyfluorene-triarylamine-based hole transport layers (HTLs). The solubility of the HTL can be tuned by adjustment of the chemical structure without loss of the charge transport properties. Double-layer polymer light-emitting diodes are constructed with an HTL that is not soluble in...

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...

Controllable molecular doping and charge transport in solution-processed polymer semiconducting layers

Here, controlled p-type doping of poly(2-methoxy-5-(20-ethylhexyloxy)- pphenylene vinylene) (MEH-PPV) deposited from solution using tetrafluorotetracyanoquinodimethane (F4-TCNQ) as a dopant is presented. By using a co-solvent, aggregation in solution can be prevented and doped films can be deposited. Upon doping the current-voltage...