Antonio Urbina

Microwave-assisted sidewall functionalization of single-wall carbon nanotubes by Diels–Alder cycloaddition

The first Diels-Alder cycloaddition of o-quinodimethane to SWNT has been performed under microwave irradiation.

Organic photovoltaic greenhouses: a unique application for semi-transparent PV?

Organic photovoltaics are an emerging solar power technology which embody properties such as transparency, flexibility, and rapid, roll to roll manufacture, opening the potential for unique niche applications. We report a detailed techno-economic analysis of one such application, namely the photovoltaic greenhouse, and discuss whether the unique properties of the technology can provide advantages over conventional photovoltaics. The potential for spectral selectivity through the choice of OPV materials is evaluated for the case of a photovoltaic greenhouse. The action spectrum of typical greenhouse crops is used to determine the impact on crop growth of blocking different spectral ranges from the crops. Transfer matrix optical modelling is used to assess the efficiency and spectrally resolved transparency of a variety of commercially available semi-conducting polymer materials, in addition to a non-commercial low-band-gap material with absorption outside that required for crop growth. Economic analysis suggests there could be a huge potential for OPV greenhouses if aggressive cost targets can be met. Technical analysis shows that semi-transparent OPV devices may struggle to perform better than opaque crystalline silicon with partial coverage, however, OPV devices using the low-band-gap material PMDPP3T, as well as a high efficiency mid-band-gap polymer PCDTBT, can demonstrate improved performance in comparison to opaque, flexible thin-film modules such as CIGS. These results stress the importance of developing new, highly transparent electrode and interlayer materials, along with high efficiency active layers, if the full potential of this application is going to be realised.

Cycloaddition of benzyne to SWCNT: towards CNT-based paddle wheels

The cycloaddition of benzyne to SWCNT has been carried out for the first time. Raman spectroscopy, TGA, HR-TEM, UV-vis-NIR as well as XPS have been used for products characterization.

Surface potential domains on lamellar P3OT structures

In this work the electrostatic properties of poly(3-octylthiophene) thin films have been studied on a nanometer scale by means of electrostatic force microscopy and Kelvin probe microscopy (KPM). The KPM images reveal that different surface contact potential domains coexist on the polymer surface. This result, together with additional capacitance measurements, indicates that the potential domains are related to the existence of dipoles due to different molecular arrangements. Finally, capacitance measurements as a function of the tip-sample bias voltage show that in all regions large band bending effects take place.

Case of study: Photovoltaic faults recognition method based on data mining techniques

Data Mining techniques have been applied to data collected from a 222 kWp CdTe (Cadmium Telluride) photovoltaic (PV) generator to predict faults or special conditions that occurs due to shadows, bad weather, soiling, and technical faults. Five types of errors have been distinguished and its impact on the PV system performance has been evaluated. Up to date, this computing approach has needed the simultaneous measurement of environmental attributes that an array of sensors collected. This study presents a model to assess the state of the PV (photovoltaic) generator and an algorithm that classifies its state without measuring ambient conditions. The result of a 222 kWp CdTe PV case study shows how the application of computing learning algorithms can be used to improve the management and performance of the photovoltaic generators and underlines the environmental parameters as clue attributes to find faults during the PV performance. Although the application of this method requires computational effort, the r...

Longer battery lifetime provided by a priority load control algorithm on stand-alone photovoltaic system

Access to electricity has a positive impact on the socio-economic activity in rural livelihoods. Stand-alone photovoltaic (SAPV) systems are the most popular PV application for rural electrification in areas nonconnected to the grid, but it is still relatively expensive. Batteries are considered as a weak component of the system, comprising an important part of the total cost and are usually replaced multiple times during PV system lifetime. A priority load control algorithm has been developed in order to gain a better energy management over system loads and the battery storage, and therefore guarantee the energy supply for critical loads and extends the battery service lifetime. This will increase the reliability of the system and the end-user satisfaction. This article describes a stand-alone PV system model used for the development of a priority load control algorithm and explains and implements the algorithm. The results of several test scenario simulations are shown and discussed.

Life cycle analysis of an off-grid solar charging kiosk

Solar power has a huge potential in electrifying rural communities, particularly in the developing world. It offers the possibility of a clean, affordable energy source which may reduce the environmental impact of existing, fossil fuel based sources. The life-cycle carbon emissions resulting from off-grid solar powered lighting solutions are an important factor influencing the environmental impact of implementing such solutions. This issue is particularly relevant when assessing the case for carbon financing for such a project. However, few studies have addressed the carbon saving potential of such off grid systems. Here, we analyse a distribution model known as a Solar Charging Kiosk which enables access to photovoltaic electricity for rural, off-grid communities. Using a kiosk which has been established in the Bugesera region of Rwanda as a model system, the carbon savings avoided from reduced use of kerosene based lighting are calculated based on real system performance and usage data of customers of the kiosk. Strategies to further increase the emissions mitigation potential of the system are proposed.

EU COST Action MP1307 — Unravelling the degradation mechanisms of emerging solar cell technologies

Organic and hybrid perovskite based solar cells have a huge potential to significantly contribute to a clean electricity supply of the future. However, so far they exhibit complex and hierarchical degradation paths and their understanding can only be acquired through the application of complementary chemical and physical characterization techniques. This limited device stability is the main hurdle for a successful and large scale market introduction of these emerging solar cell technologies. Our StableNextSol Action has created a highly interdisciplinary network of laboratories, as well as corresponding industry, overall more than 120 partners, with complementary analytical techniques for the study and understanding of the degradation mechanisms occurring in state-of-the-art devices. Our Action integrates and generates fundamental knowledge and expertise to foster disruptive innovations targeted to mitigate device failure and to propose and develop new concepts for more stable solar cells. Value is added to the entire value chain of photovoltaic research at European and international level, as well as variety decision makers in the public sector by supporting specialisation policy and standards still lacking in this research field. The outcome of the Action will contribute to resolve the global challenges facing the industry and this COST Action initiative has brought together all these expertises and resources to promote the cooperation between different sectors, academia, public authorities and industry.