Cтруктурні, оптичні і термоелектричні властивості плівок та наночастинок ZnO, CZTS, CZTSe для фото- і термоперетворювачів

Дисертаційна робота присвячена оптимізації основних фотоелектричних характеристик, а саме квантового виходу (Q), густини струму короткого замикання (Jsc), ефективності (η) плівкових ФЕП на основі ГП n-CdS(ZnSe, ZnS)/p-(CZTS, CdTe) із струмознімальними контактами n-ITO(ZnO); дослідженню морфологічних особливостей, структурних, субструктурних, оптичних, термоелектричних властивостей та елементного складу плівок ZnO, CZTS, нанесених методом пульсуючого спрей піролізу, для використання у ФЕП та наноструктурованого матеріалу на основі НЧ CZTSe, синтезованих колоїдним методом, для застосування у ТЕП, що можуть працювати паралельно з ФЕП. Встановлені взаємозв’язки між фізико- та хіміко-технологічними умовами нанесення плівок та синтезу НЧ, наноструктурованого матеріалу на їх основі, та структурними, субструктурними, оптичними, термоелектричними властивостями, елементним складом будуть використані для подальшого створення ФЕП та ТЕП з покращеними характеристиками.Диссертационная работа посвящена оптимизации основных фотоэлектрических характеристик, а именно квантового выхода (Q), плотности тока короткого замыкания (Jsc), эфективности (η) плёночных ФЭП на основе ГП n-CdS(ZnSe, ZnS)/p-(CZTS, CdTe) с токособирающими контактами ITO(ZnO); исследованию морфологических особенностей, структурных, субструктурных, оптических, термоэлектрических свойств и элементного состава плёнок ZnO, CZTS, нанесённых методом пульсирующего спрей-пиролиза, для применения у вышеуказанных ФЭП и наноструктурированного материала на основе НЧ CZTSe, синтезированных колоидальным методом, для использования у ТЭП, которые могут работать паралельно с ФЭП. Установленные взаимосвязи между физико- и химико-технологическими условиями нанесения плёнок, синтеза НЧ, наноструктурированного материала на их основе, и структурными, субструктурными, оптическими, термоэлектрическими свойствами, элементным составом будут использованы для создания ФЭП и ТЭП с улучшенными характеристиками.PhD thesis is devoted both to the optimization of basic photoelectric characteristics (quantum yield (Q), density of short circuit current (Jsc), efficiency (η)) of solar cells based on n-CdS(ZnSe, ZnS)/p-(CZTS, CdTe) heterojunctions with n-ITO(ZnO) frontal contacts, and to the investigation of morphological, structural, substructural, optical, thermoelectric properties and chemical composition of: (I) ZnO, CZTS films deposited by spray pyrolysis for application in solar cells; (II) nanostructured materials based on CZTSe nanocrystals synthesized by colloidal method for application in thermoelectric devices which can work simultaneously with solar cells. In the work, modeling approbation was performed by means of investigating the effect of optical and recombination losses on Q, Jsc, η of solar cells based on n-CdS(ZnS)/p-CdTe heterojunctions. Afterwards, the investigation of these losses on the photoelectric characteristics of solar cells based on n-CdS(ZnSe, ZnS)/p-CZTS heterojunctions with n-ITO(ZnO) frontal contacts was carried out with the help of the approbated procedure. Taking into account the results of mathematical modeling, the solar cells based on ZnO frontal contact and CZTS absorber layer were considered. For this purpose, the automated setup for the deposition of ZnO and CZTS films by pulsed spray pyrolysis technique was developed. The in-depth investigation of influence of the main growth conditions of layers’ deposition (substrate temperature (Ts), volume of initial precursor (Vs)) on structural (grains size, phase composition, texture quality, lattice parameters), substructural (coherent scattering domain sizes, level of microdeformations and microstresses, density of dislocations at the boundaries and in the volume of subgrains), optical (transmission coefficients, absorbance, band gap) properties and chemical composition of ZnO, CZTS films, as well as the determination of optimal conditions to obtain the specified films were carried out. Since the solar cells operate at the elevated temperatures, it was proposed to use the additional thermal energy by means of its conversion into electrical energy by use of the thermoelectric devices. For this purpose, the nanostructured thermoelectric material based on CZTSe nanocrystals synthesized by the colloidal method was obtained. The influence of kinetic conditions, namely type of phosphonic acid, on morphological (size, shape), structural (phase composition), optical (absorbance, band gap) properties and chemical composition of CZTSe nanocrystals was determined. The influence of chemical composition on the main thermoelectric properties (concentration (p) and mobility ( u ) of majority charge carriers, relative electrical conductivity ( k ), Seebeck coefficient (SZ)) of nanostructured material based on CZTSe nanocrystals was investigated. The established correlations between the film, nanocrystals growth conditions and structural, substructural, optical, thermoelectric properties, chemical composition will be applied for further development of solar cells and thermoelectric devices with the enhanced characteristics

Cereal yield gaps across Europe

peer-reviewedEurope accounts for around 20% of the global cereal production and is a net exporter of ca. 15% of that production. Increasing global demand for cereals justifies questions as to where and by how much Europe’s production can be increased to meet future global market demands, and how much additional nitrogen (N) crops would require. The latter is important as environmental concern and legislation are equally important as production aims in Europe. Here, we used a country-by-country, bottom-up approach to establish statistical estimates of actual grain yield, and compare these to modelled estimates of potential yields for either irrigated or rainfed conditions. In this way, we identified the yield gaps and the opportunities for increased cereal production for wheat, barley and maize, which represent 90% of the cereals grown in Europe. The combined mean annual yield gap of wheat, barley, maize was 239 Mt, or 42% of the yield potential. The national yield gaps ranged between 10 and 70%, with small gaps in many north-western European countries, and large gaps in eastern and south-western Europe. Yield gaps for rainfed and irrigated maize were consistently lower than those of wheat and barley. If the yield gaps of maize, wheat and barley would be reduced from 42% to 20% of potential yields, this would increase annual cereal production by 128 Mt (39%). Potential for higher cereal production exists predominantly in Eastern Europe, and half of Europe’s potential increase is located in Ukraine, Romania and Poland. Unlocking the identified potential for production growth requires a substantial increase of the crop N uptake of 4.8 Mt. Across Europe, the average N uptake gaps, to achieve 80% of the yield potential, were 87, 77 and 43 kg N ha−1 for wheat, barley and maize, respectively. Emphasis on increasing the N use efficiency is necessary to minimize the need for additional N inputs. Whether yield gap reduction is desirable and feasible is a matter of balancing Europe’s role in global food security, farm economic objectives and environmental targets.We received financial contributions from the strategic investment funds (IPOP) of Wageningen University & Research, Bill & Melinda Gates Foundation, MACSUR under EU FACCE-JPI which was funded through several national contributions, and TempAg (http://tempag.net/)

Impacts of model structure and data aggregation on European wide predictions of nitrogen and green house gas fluxes in response to changes in livestock, land cover, and land management

Various model approaches have been developed for assessing emissions of different forms of reactive nitrogen in various parts of Europe at various geographic resolutions and for various time periods. The modeling approaches include emission factor approaches, empirical models, simple process-based models, and detailed ecosystem models. In this study, we compared three relatively simple process-based models, developed for the national scale (Integrated NITrogen Impact AssessmenT model On a Regional Scale (INITIATOR2)), European scale (MITERRA) and global scale (integrated model to assess the global environment (IMAGE)), with respect to their response to structural and technological changes in the agricultural systems based on the IPCC B2 baseline scenario for the period 2000-2030. Changes are predicted by the IMAGE model and relate to crop yield, crop area, animal numbers, and N fertilizer inputs. The predicted relative changes by IMAGE are used in INITIATOR2 and MITERRA while relating the animal categories and crop categories in IMAGE to those in the latter models. A comparison was made of NH3, N2O and NOx emissions and N leaching to ground water. We compared predictions for the years 2000 and 2030 for: (i) the Netherlands between INITIATOR2 and MITERRA and (ii) Europe (EU-27 countries) between MITERRA and IMAGE. The results of the comparison are presented and evaluated in view of differences in model structure and the effect of aggregating input data at larger spatial scales

Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive; a benchmark study

Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the northwest of the European Union (Ireland, United Kingdom, Denmark, the Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting period for the NiD (2004–2007) and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus), particularly in Belgium, Denmark, Ireland, the Netherlands and the United Kingdom. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of the Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha−1 yr−1 lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50 kg N ha−1 yr−1. Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross-boundary policy evaluations are handicaps when benchmarking the effectiveness of the NiD. This provides a challenge for the European Commission and its member states, as the NiD remains an important piece of legislation for protecting drinking water quality in regions with many private or small public production facilities and controlling aquatic eutrophication from agricultural sources