Dimitrios Raptis

Perovskite solar cell with low cost Cu-phthalocyanine as hole transporting material

Low cost copper phthalocyanine has been used as hole-transporting material for the construction of organolead halide solid state perovskite solar cells. The cells were assembled and tested under ambient conditions. They achieved a power conversion efficiency of 5.0% using copper phthalocyanine, which appears to have potential to replace the currently used organic hole transporters. The present work has also examined the possibility of upscaling by construction of small cell modules.

The 4C framework: principles of interaction in digital ecosystems

Recent years have seen an increased research interest in multi-device interactions and digital ecosystems. This research addresses new opportunities and challenges when users are not simply interacting with one system or device at a time, but orchestrate ensembles of them as a larger whole. One of these challenges is to understand what principles of interaction work well for what, and to create such knowledge in a form that can inform design. Our contribution to this research is a framework of interaction principles for digital ecosystems, which can be used to analyze and understand existing systems and design new ones. The 4C framework provides new insights over existing frameworks and theory by focusing specifically on explaining the interactions taking place within digital ecosystems. We demonstrate this value through two examples of the framework in use, firstly for understanding an existing digital ecosystem, and secondly for generating ideas and discussion when designing a new one.

Aesthetic, Functional and Conceptual Provocation in Research Through Design

Recently within HCI, design approaches have appeared, which deviate from traditional ones. Among them critical design introduces deliberate provocations in order to challenge established perceptions and practices. We have engaged ourselves with this design approach out of interest in understanding how to use provocation in research through design. Towards this end, we report on a field study with four families that used an aesthetically, functionally and conceptually provocative future probe. The purpose of the probe was to challenge existing energy consuming practices through provocation and make its users reflect on them. The paper describes how all three provocative aspects were addressed, and our findings demonstrate how they were experienced in the real world, and how they impacted our research through design approach. We conclude by presenting reflections on how to design provocations, and reflections on the impact of provocations for research through design in general.

BiOI solar cells

An inorganic solar cell was constructed using a thin compact supporting layer of titania with BiOI nanoflakes as a functional material, a Pt/FTO cathode and a I3−/I− redox electrolyte. The efficiency of the cell was 1.03% but this leaves a lot of ground for improvement, which is mainly expected to come from the optimization of the BiOI nanostructure.

Renewable energy production by photoelectrochemical oxidation of organic wastes using WO3 photoanodes

The present work has studied renewable hydrogen production by photoelectrocatalytic degradation of model organic substances representing biomass derived organic wastes. Its purpose was to show that renewable energy can be produced by consuming wastes. The study has been carried out by employing nanoparticulate WO3 photoanodes in the presence of ethanol, glycerol or sorbitol, i.e. three substances which are among typical biomass products. In these substances, the molecular weight and the number of hydroxyl groups increases from ethanol to sorbitol. The photocurrent produced by the cell was the highest in the presence of ethanol, smaller in the case of glycerol and further decreased in the presence of sorbitol. The photocurrent was roughly the double of that produced in the absence of an organic additive thus demonstrating current doubling phenomena. Hydrogen was produced only under illumination and was monitored at two forward bias, 0.8 and 1.6V vs Ag/AgCl. Hydrogen production rates followed the same order as the photocurrent thus indicating that hydrogen production by reduction of protons mainly depends on the current flowing through the external circuit connecting photoanode with cathode. The maximum solar-to-hydrogen efficiency reached by the present system was 2.35%.

Investigating Cross-Device Interaction between a Handheld Device and a Large Display

There is a growing interest in HCI research to explore cross-device interaction, giving rise to an interest in different approaches facilitating interaction between handheld devices and large displays. Contributing to this, we have investigated the use of four existing approaches combining touch and mid-air gestures, pinching, swiping, swinging and flicking. We look specifically at their relative efficiency, effectiveness and accuracy in bi-directional interaction between a smartphone and large display in a point-click context. We report findings from two user studies, which show that swiping is both most effective, fastest and most accurate, closely followed by swinging. What these two approaches have in common is the ability to keep the pointer steady on the large display, unaffected by concurrent gestures or body movements used to complete the interaction, suggesting that this is an important factor for designing effective cross-device interaction with large displays.

Copolymers of ionic liquids with polymeric or metallocomplex chromophores for quasi-solid-state DSSC applications

The development of copolymers based on ionic liquid vinyl monomers of the imidazole family combined with polymerizable chromophoric units is presented herein. For this end, ruthenium complexes bearing polymerizable vinyl groups or ω-end vinyl rr-poly(3-alkyl thiophene) were prepared and copolymerized with the ionic liquid monomers under free radical polymerization conditions, affording chromophore/polyelectrolyte combinations. Homopolymer ionic liquids were also synthesized to select the optimum conditions for the copolymers thereafter. All the monomers and polymers were characterized for their optical properties, and were also structurally characterized using various complementary techniques. Selected copolymers and homopolymers were tested in quasi-solid-state sensitized solar cells based on titania and regioregular poly(3-hexyl thiophene) acting as a hole-transporting semiconducting polymer. The ionic liquid, which is miscible with the hole-conductor and can be deposited with the latter, provides a functionality that, in some cases, supports an increase in open-circuit voltage, thus increasing cell efficiency.

Understanding "cool" in human-computer interaction research and design

Recently a discussion has been initiated on what is cool and how HCI can use the concept in practice and design for it. This paper aims to provide a better understanding on cool as a concept from a theoretical and a practical perspective. From the theoretical perspective, we selected the HCI papers that focus on cool and we present their core findings. Then we performed a literature review on the concept of cool and we have identified its fundamental characteristics, through cool personalities and cool styles. From a practical perspective, we have studied how other domains have managed to successfully produce cool objects and we provide four suggestions on how to design cool digital artifacts. Finally, in this paper we also identify possible research directions in relation to cool, which if we manage to address we can increase our understanding on what is user experience and this can lead to the creation of better digital artifacts. Overall, this paper is a contribution towards researching and designing for cool, a research topic, which we believe it will initiate fruitful discussions in the HCI field.

Converging coolness and investigating its relation to user experience

ABSTRACT Recently a number of studies appeared that operationalised coolness and explored its relation to digital products. Literature suggests that perceived coolness is another factor of user experience, and this adds to an existing explosion of dimensions related to aesthetics, hedonic quality, pragmatic quality, attractiveness, etc. A critical challenge highlighted in prior research is to study the relationships among those factors and so far, no studies have empirically examined the relationship between coolness and other established user experience factors. In this paper, we address this challenge by presenting two studies one that focuses on factors from two cool questionnaires, and one that compares them against existing User eXperience (UX) factors. Our findings show that factors from the two cool questionnaires converge and they also converge to existing, established UX factors. Thus, 11 distinct cool and UX factors converge into 5 for the case of mobile devices. Our findings are important for researchers, as we demonstrate through a validated model that coolness is part of UX research, as well as for practitioners, by developing a questionnaire that can reliably measure both perceived inner and outer coolness as well as the overall coolness judgement based on 5 factors and 21 items.

Investigation of efficient protocols for the construction of solution-processed antimony sulphide solid-state solar cells

Antimony sulfide solar cells have been studied with the purpose to investigate an easy and efficient procedure of antimony sulfide deposition on mesoporous titania films. Two principal deposition methods have been studied based on different sulfur precursors (thiosulfate vs. thiourea) and chemical bath vs. spin-coating deposition. The two approaches led to the same practical effect thus highlighting spin-coating deposition using antimony chloride and thiourea as the simplest and most practical method of construction of antimony sulfide/titania photoanodes. Poly(3-hexylthiophene) was employed as a hole-transporter while PEDOT:PSS and Ag were used as the counter electrode. They were all deposited under ambient conditions. XPS measurements provided information about antimony sulfide stoichiometry while UPS measurements gave the ionization potential in each case. Both deposition methods led to sulfur-deficient antimony sulfide.