Origin and Energy of Intra-Gap States in Sensitive Near-Infrared Organic Photodiodes

Trap states in organic semiconductors are notoriously detrimental to the performance of organic electronics. However, the origin and energetics of trap states remain largely elusive and under debate, especially for bulk-heterojunction (BHJ) photodiodes consisting of electron donor and acceptor materials. Combining three sensitive techniques now...

Transport in Mn spinel oxides alloyed with Zn–Ni: Polaron hopping in an inhomogeneous energy landscape

Electronic transport in transition metal spinel oxides is associated with small polaron hopping, either nearest-neighbor, resulting in Arrhenius activated conductivity, or variable energy, leading to a sub-Arrhenius relationship, with the conductivity logarithm being a convex function of inverse temperature. For the case of manganese spinel...

Identification of the Origin of Ultralow Dark Currents in Organic Photodiodes

Organic bulk heterojunction photodiodes (OPDs) attract attention for sensing and imaging. Their detectivity is typically limited by a substantial reverse bias dark current density (Jd). Recently, using thermal admittance or spectral photocurrent measurements, Jd has been attributed to thermal charge generation mediated by mid-gap states. Here,...

Determination of the temperature dependency of the electrical parameters of CIGS solar cells

Two types of Cu(In,Ga)Se2 (CIGS) solar cells, both designed for implementation in CIGS modules, were subjected to temperatures between 25C and 105C. Simultaneous exposure to AM1.5 illumination allowed the measurement of their electrical parameters at these temperatures. These two types of solar cells, produced with different deposition routes on...

Path homogeneity along a horizontal line-of-sight path during the FESTER experiment: First results

The First European South African Experiment (FESTER) was conducted over about a 10 month period at the Institute of Maritime Technology (IMT) in False Bay, South Africa. One of the important goals was the establishment of the air-sea temperature difference (ASTD) homogeneity along the main propagation link atmospheric path since it is a basic...

Identifying parasitic current pathways in CIGS solar cells by modelling dark J-V response

An equivalent circuit model, which allows for the presence of three types of shunting pathways, has been developed to describe the dark J-V characteristics in CIGS solar cells. Excellent agreement between the model and experimental data was apparent throughout a temperature range of 183-323K. Voltage-independent ideality factors may be extracted...

Numerical modeling of thermal performance: Natural convection and radiation of solid state lighting

The increased electrical currents used to drive light emitting diode (LED) cause significant heat generation in the solid state lighting (SSL) system. As the temperature will directly affect the maximum light output, quality, reliability and the life time of the SSL system, thermal management is a key design aspect in terms of cost and...

Multi-band optical/IR transmissometry during the VAMPIRA trials, spring 2004

Scattering by atmospheric aerosols is one of the environmental parameters determining the range performance of optical and infrared sensors. Extinction of the target contrast along the path due to scattering is difficult to estimate in real operational conditions due to uncertainties in the size distribution of the particles, their constitution...

Ship Infrared Detection/Vulnerability

The IR contrast of ships at sea is of importance for those who want to detect or identify the ship and for those who worry about this. This IR contrast is determined by a large number of parameters. Of course temperatures of the ship's structure and those of the ambient sea and air are important, but also important are the reflection properties...

Comparison of displacement and mixing diffusers

In order to compare the performance of different supply diffusers of ventilation air, the airflow pattern, temperature stratification and contaminant dispersion in a furnitured office ventilated by three kinds of air diffuser were numerically investigated. The air diffusers studied in this paper are a quarter-cylinder displacement diffuser on...