Радиационно-физические аспекты переноса носителей заряда в молекулярно допированном полистироле
Hole transport in low-polarity polystyrene (PS) doped with 10 wt % tritolylamine was studied. The radiation induced mode of the time-of-flight technique (TOF) with the carrier generation zone of a variable thickness was used. A theoretical treatment of the data in terms of the Gaussian disorder model has shown the mobility value to be fundamentally inconsistent with the flat shape of the plateau, a contradiction that cannot be resolved within the framework of this model. It has been shown that hole transport is actually dispersive, rather than quasi-equilibrium. The contribution of radiation conductivity of the polymer matrix to the TOF signal was evaluated.
Abstract—General questions about hole transport and bimolecular recombination of charge carriers in molecularly doped polycarbonate with a low dopant concentration (10 wt %) are considered. The experiment is performed via a radiationinduced timeofflight technique with bulk generation of charge carriers. Tran sientcurrent curves are calculated numerically via a multipletrapping model. There is good agreement between the calculated and experimental results on the transientcurrent waveform. Nonequilibrium hole transport is observed in the studied molecularly doped polymer, and the bimolecular recombination is close to the Langevin recombination as described by the multipletrapping model.
Owing hysteresis free characteristics and good reproducibility, inverted p-i-n perovskite solar cells (PSC) are gaining large interest in the photovoltaic field. In this context, the need for stable materials calls for the development of robust transporting layers compatible with the fabrication processes of the solar cell. In this study, we introduce a new precursor, tris(ethylene diamine) nickel acetate, for low temperature (280–300 1C) deposition of NiO hole transporting layer. Full characterization of the deposited NiO film layer was performed through XRD, Raman and Auger spectroscopy. We found a direct correlation between device performance and NiO thickness with maximum efficiency exceeding 15% for the thin NiO (10 nm) layer.
The effect of preliminary electron beam irradiation on hole transport in a molecularly doped polymer was studied with the use of the time of flight technique in the radiation_induced mode. Specimens that exhibit a plateau on their time of flight curves were selected for the study, since they suggest the occurrence of quasi equilibrium transport in the system according to the conventional point of view. In the extremely small signal mode, current transients in the case of bulk irradiation have a form corresponding to dispersive, rather than Gaussian, transport, although hole movement is observed in the presence of charged sites (trapped electrons). On passing to the moderately large signal mode (preirradiation to a dose of up to 5 Gy), the current transients undergo noticeable changes, which might be mistakenly interpreted as evidence for the influence of charged sites on hole transport in accordance with the predictions of the dipolar glass theory. In actuality, these changes are due to the effect of a space charge field and the hole mobility remains almost unchanged in this case. The appearance of the plateau on the current transients is an artifact of the procedure, and the hole transport is dispersive.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.