Physical and chemical degradation behavior of sputtered aluminum doped zinc oxide layers for Cu(In,Ga)Se2 solar cells

Sputtered aluminum doped zinc oxide (ZnO:Al) layers on borosilicate glass were exposed to damp heat (85 C/85% relative humidity) for 2876 h to accelerate the physical and chemical degradation behavior. The ZnO:Al samples were characterized by electrical, compositional and optical measurements before and after degradation. Hall measurements show...

Real-time NO2 detection at ppb level with ZnO field-effect transistors

We present a functional real-time NO2 sensor based on a ZnO field-effect transistor. The dynamic response of the sensor is calculated using a phenomenological charge trapping model, using only experimentally determined parameters. This analytical model is implemented in the sensor protocol to create a hardware demonstrator sensor. We show that...

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...

Non-radiative recombination losses in polymer light-emitting diodes

We present a quantitative analysis of the loss of electroluminescence in light-emitting diodes (LEDs) based on poly[2-methoxy-5-(2′-ethylhexyloxy)- p-phenylenevinylene] (MEH-PPV) due to the combination of non-radiative trap-assisted recombination and exciton quenching at the metallic cathode. It is demonstrated that for an MEH-PPV LED the...

Gate-bias controlled charge trapping as a mechanism for NO2 detection with field-effect transistors

Detection of nitrogen dioxide, NO2, is required to monitor the air-quality for human health and safety. Commercial sensors are typically chemiresistors, however field-effect transistors are being investigated. Although numerous investigations have been reported, the NO2 sensing mechanism is not clear. Here, the detection mechanism using ZnO...

Optical detection of deep electron traps in poly(p-phenylene vinylene) light-emitting diodes

The trap-limited electron currents in poly(p-phenylene vinylene) (PPV) derivatives can be modeled using a Gaussian trap distribution that is positioned approximately 0.75 eV below the lowest unoccupied molecular orbital (LUMO) of PPV. Photothermal deflection spectroscopy measurements and internal photo-emission spectroscopy measurements confirm...

Electron trapping in higher adduct fullerene-based solar cells

Here, the performance of bulk-heterojunction solar cells based on a series of bisadduct analogues of commonly used derivatives of C60 and C 70, such PCBMs and theirthienyl versions, is investigated. Dueto their higher lowest unoccupied molecular orbital an increase in open-circuit voltage and thus performance is expected. It is shown that the...

Electron-enhanced hole injection in blue polyfluorene-based polymer light-emitting diodes

It has recently been reported that, after electrical conditioning, an ohmic hole contact is formed in poly(9,9-dioctylfluorene) (PFO)-based polymer light-emitting diodes (PLED), despite the large hole-injection barrier obtained with a poly(styrene sulfonic acid)-doped poly(3,4-ethylenedioxythiophene) (PEDOTPSS) anode. We demonstrate that the...