We examine the dark and the illuminated current–voltage
(J–V) characteristics of poly(3-octylthiophene) (P3OT)/single-wall carbon nanotube
(SWNT) composite photovoltaic cells as a function of SWNT concentration. Using
an exponential band tail model, the influence of SWNT concentration on the
J–V
characteristics of the cells is analysed in terms of corresponding parameters such as
effective hole mobility, short-circuit current, and open-circuit voltage. For the
device with optimum 1% SWNT concentration, the increased photoresponse
(∼500
times) as compared to the pristine P3OT cell can be attributed partly to the increase
(∼50
times) in effective hole mobility, due to the reduction of localized states of the pristine
P3OT matrix, and partly to the enhanced exciton extraction at the polymer/nanotube
junctions.
Abstract. In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We employ gaussian-shaped filters as well as actual filter transmission curves, mainly AERONET data, to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. Published parameterized transmittance functions are applied to the data to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. The moderateresolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940-nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10 −6 to 10 −4 , and typical response curves of commercially available silicon photodiodes are included into the calculations.It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is mainly underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. Further investigations will use experimental data from field campaigns to validate these findings.
A simple and easy to implement, ion time-of-flight (TOF), detection system has been developed and used to monitor the ions ejected during pulsed excimer laser ablation of solid and molten Si and Ge targets. The setup employs a Faraday cup (FC) detector with a high gain-bandwidth preamplifier and an adjustable voltage electrostatic barrier. The FC is capable of very long time, undisturbed, operation even with significant deposition of material on it. The analysis of the TOF ion signal and its modification by the barrier potential yields valuable quantitative information about the ion flux and kinetic energy at the surface of the growing film. The technique is capable of resolving atomic/cluster components of different charge to mass ratios. High ion fractions and ion energies are observed, in all cases studied, when the laser fluence is clearly above the ablation threshold.
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