The mechanisms limiting the dark current in pentacene (Pc)/C60 solar cell were determined using the temperature dependence of the current-density-voltage characteristics. Our analysis allowed us to calculate the effective barrier height for electrons and holes at the interface. We then determined the built-in potential of the heterojunction and the effective doping concentration of the active layers, using capacitance-voltage characteristics. These physical parameters were used to simulate a band-energy diagram for a Pc/C60 solar cell in equilibrium. Finally, we determined a relation between the effective barrier height and the built-in potential.

The dark current-voltage characteristics of poly (3-hexylthiophene) (P3HT)/n-type crystalline silicon solar cells were analyzed using an electrical equivalent circuit. We found that without illumination transport occurs due to hopping between localized states at the P3HT/silicon interface not only at low voltages, through multitunneling capture emission, but also at medium voltages, through tunneling-enhanced recombination. At high voltages the current is limited by series resistance and space-charge limited mechanisms. At low reverse voltages the current is limited by shunt resistance. From the temperature dependence of the equivalent circuit’s fitting parameters, we were able to estimate some physical parameters of the P3HT layer, namely the electron affinity, the charge carrier concentration and the characteristic temperature of the exponential trap distribution. The extracted P3HT values are in good agreement with previously reported values obtained using different methods but our approach takes into account that the P3HT layer is in a solar cell.

This paper presents a compact electrical equivalent circuit which describes the dark current-voltage characteristics of nonideal p-n junction solar cells in a wide range of temperatures. The model clearly separates the voltage drop in the junction and bulk regions. It is based on the combination of two exponential mechanisms, shunt and series resistances and space-charge limited current. In order to increase the accuracy of the parameter extraction process, both ln(I-V) and its derivative plots are fitted simultaneously. From the temperature dependence of the extracted parameters, the conduction mechanisms governing the I-V characteristics can be obtained without assuming dominating terms. In addition, the extracted parameters can be related to other electrical magnitudes obtained from such independent measurements as capacitance-voltage measurements (diffusion potential) and illuminated current-voltage characteristics (series resistance and open-circuit voltage). To exemplify the application, a p+ a-SiC:H∕n c-Si solar cell is studied and a number of major physical aspects derived from the analysis of the fitting values are discussed.

El ciberacoso ha suscitado el interés de los investigadores en el campo de la psicología. Una de las variables que se ha estudiado en los últimos años en relación con el ciberacoso es la ansiedad social. Sin embargo, no se ha realizado una evaluación global y específica de los resultados en estas dos grandes áreas. El objetivo de este estudio es sintetizar los resultados de los estudios que analizan la asociación entre la ansiedad social y el ciberacoso. Se realizó una revisión sistemática de estudios publicados en Web of Science y PsycINFO. Los criterios de inclusión de los estudios fueron: (1) analizar la relación entre la ansiedad social y las experiencias de ciberacoso; (2) centrados en niños y adolescentes entre 9 a 19 años; (3) publicados entre 1996 a 2016; y (4) disponibles en inglés. De las 287 publicaciones encontradas inicialmente, 13 estudios cumplieron con los criterios de inclusión. En los estudios transversales se encontró que existe mayoritariamente una relación positiva entre AS y CA. Dos estudios concluyeron que la ansiedad social predice un aumento de las experiencias de cibervictimización. Cuatro estudios no encontraron la ansiedad social como consecuencia psicológica de las experiencias de cibervictimización; mientras que uno sí encontró relación. El ciberacoso generalmente no se relacionó con mayores niveles de ansiedad social. La mayoría de estudios indicaron que la ansiedad social es un factor de riesgo para la cibervictimización, y en menor medida una consecuencia de ésta. Investigaciones futuras con diseños longitudinales son necesarias para analizar las asociaciones bidireccionales de la ansiedad social y el ciberacoso.

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