1,720,964 research outputs found
Design and Characterization of Hybrid Perovskite for New Generation Solar Cells
Full text linkLe perovskiti sono semiconduttori con caratteristiche optoelettroniche ideali per l’applicazione fotovoltaica (elevato assorbimento, alta mobilità di carica) e con un basso costo. Tuttavia, la loro applicazione commerciale è limitata dall’instabilità di questo materiale. Il degrado della perovskite è causato da alcuni fattori esterni come ossigeno e umidità.
In questa tesi sono state studiate entrambe le strutture (NIP e PIN) delle celle solari a perovskite. Per renderle più stabili ed efficienti sono state trattate con nuovi metodi di passivazione e con materiali di recente sintesi che hanno portato al raggiungimento dell’obiettivo. Sono state anche usate diverse tecniche di caratterizzazione per comprendere le ragioni dei miglioramenti nelle prestazioni di questi dispostivi. Questo ha permesso di ottenere una maggiore conoscenza dei meccanismi dei miglioramenti e di conseguenza a una più vicina commercializzazione di questo materiale.Perovskites are semiconductors with ideal optoelectronic properties (like high absorption and high charge mobility) for photovoltaic applications and at a low cost. However, their commercial application is limited by the instability of this material. The degradation of perovskite is caused by some external factors such as oxygen and humidity.
In this thesis both structures (NIP and PIN) of perovskite solar cells have been studied. To make them more stable and efficient, they have been treated with new passivation methods and with recently synthesized materials that have led to the achievement of the goal. Various characterization techniques were also used to understand the reasons for the performance improvements of these devices. This allowed obtaining a greater knowledge of the mechanisms of the improvements and consequently to closer commercialization of these perovskites
Smart Materials to Empowering Perovskite Solar Cells with Self‐Healing Capability
No full textInspired by nature, intelligent self-healing materials have recently been exploited also in the field of photovoltaics to mimic natural systems achieving self-repairing. The past decade has witnessed perovskite solar cells (PSCs) skyrocketing to a certified power conversion efficiency of 26.1%. However, their intrinsic instability, when exposing to moisture, high temperature, and continuous illumination, hampers their commercial development for a long-term use in ambient operating conditions. Therefore, the use of smart self-healing materials, based on self-assembling properties and dynamic interactions, empowers PSCs with self-recovery abilities to reinforce their pivotal role as efficient photovoltaic devices and encourage their exploitation in the market. Herein, the current progress in self-healing perovskite materials with a special focus on self-recovery after moisture exposure or mechanical damage with the aim to provide a valuable insight for research on this topic to accelerate the PSC commercialization process is highlighted
Sustainable decommissioning of perovskite solar cells: from waste to resources
No full text: Perovskite solar cells (PSCs) have witnessed a rapid progression as emerging alternatives for innovative photovoltaics (PVs). However, this promising growth also comes with challenges related to the end-of-life (EoL) management of exhausted devices. In this review, we discuss different studies on the implications of the decommissioning of PSCs from a sustainable perspective by reviewing current PSC recycling strategies as general guidelines in the field of EoL PSCs. We hope that this review would encourage the necessary development of more virtuous energy-efficient and environmentally friendly recycling protocols for PSC recovery, from lab- to large-scale application in view of perovskite-based PV technology's imminent jump to the market
Molecular cation and low-dimensional perovskite surface passivation in perovskite solar cells
No full textThe deposition of large ammonium cations onto perovskite surfaces to passivate defects and reduce contact recombination has enabled exceptional efficiency and stability in perovskite solar cells. These ammonium cations can either assemble as a thin molecular layer at the perovskite surface or induce the formation of a low-dimensional (usually two-dimensional) perovskite capping layer on top of the three-dimensional perovskite. The formation of these two different structures is often overlooked by researchers, although they impact differently on device operation. In this Review, we seek to distinguish between these two passivation layers. We consider the conditions needed for the formation of low-dimensional perovskite and the electronic properties of the two structures. We discuss the mechanisms by which each method improves photovoltaic efficiency and stability. Finally, we summarize the knowledge gaps that need to be addressed to better understand and optimize ammonium cation-based passivation strategies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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