Silicon heterojunction solar cells (HJSC) with the efficiency of about 20% are manufactured. Their short-circuit current, open-circuit voltage, photoconversion efficiency, and fill factor of the current–voltage curve are measured in a broad temperature range from 80 to 420 K. It is established that the open-circuit voltage, the fill factor, and the photoconversion efficiency are non-monotonic functions of temperature, having a maximum in the vicinity of 200 K. A new approach to modeling of HJSCs is proposed, which allows one to obtain quantitative agreement with the experimental results at temperatures above 200 K, as well as to describe the results published in the literature on the solar cells under AM1.5 conditions. The temperature coefficient of photoconversion efficiency in HJSCs is discussed, and its low value is shown to be related to the low surface and volume recombination rates. Finally, a theoretical expression for the SC's temperature under natural working conditions is derived.
Local emission characteristics of microscopic emission sites on the surface of large-area field emitters are among the most important factors influencing macroscopic emission properties. This work aimed to evaluate the local field emission characteristics using a computerized field emission projector and a technique involving multichannel recording of current–voltage characteristics. The model field emitter consisted of nanocomposite multiwall carbon nanotubes in a polymer matrix.
Results are presented on the photoluminescence of plasma deposited amorphous carbon (a-C:H) films. Emission and exci tation spectra anti-Stokes emission, PL decay and fatigue, T-dependence of PL and photobleaching were mesuared. The data are discussed in terms of radiative recombination of the strongly localized electron-hole pairs.As recently shown, in amorphous hydrogenated carbon films (a-C:H) powerful talls of localized states occur in the mobility gap that are due to a high degree of structural disorder [1] while a radiative recombination in this material is highly efficient [2, 3]. These properties, in our view, make a-C:H suitable for verification of models of recombination kinetics of photoexcited charge carriers in highly disordered systems with the use of photoluminescence (PL).
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