Alessandro Romeo

University of Verona | UNIVR · Department of Computer Science

In this work, for the first time, CdSe is applied as a buffer layer on thermally evaporated Sb2Se3-based solar cells on superstrate configuration. The influence of this buffer layer on the growth of Sb2Se3 and the performance of the finished devices have been analyzed and compared with the typical CdS/Sb2Se3 junction. Selenium vacancies in Sb2Se3...

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g., combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters...

Recently, the introduction of a CdSe x Te 1-x (CST) buffer in the CdTe absorber has increased the photon absorption at both short wavelengths in the visible range (by removal of the parasitic absorption of the CdS layer) and at the infrared range (by reduction of the absorber band gap). But, moreover, the efficiency improvement is also attributed t...

In this contribution, we present the spectroscopic study of two NIR emitting hydrophobic heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N′-bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine), both in methanol solution and embedded in water dispersible and bioco...

CdTe solar cells are the most successful thin film photovoltaic technology of the last ten years. It was one of the first being brought into production together with amorphous silicon (already in the mid 90 s Solar Cells Inc. in USA, Antec Solar and BP Solar in Europe were producing 60 × 120 cm modules), and it is now the largest in production amon...

We report the first example of very efficient NIR Circularly Polarized Luminescence (CPL) (around 970 nm) in water, obtained thanks to the combined use of a chiral Yb complex and of poly lactic‐co‐glycolic acid (PLGA) nanoparticles. [YbL(tta)2]CH3COO (L=N, N’‐bis(2‐pyridylmethylidene)‐1,2‐(R,R+S,S) cyclohexanediamine and tta=2‐thenoyltrifluoroaceto...

Despite the slow efficiency development, Cu 2 ZnSn(S,Se) 4 still is a promising absorber material for solar cells for its easy and low cost way of fabrication and the abundance of its elements. Similarly, also CdTe faced a long period when the record efficiency would not improve over 16.5% until a different paradigm was introduced. CZTSSe, compared...

Antimony selenide (Sb2Se3) has been developed as attractive, non-toxic and earth-abundant solar absorber candidate among the thin-film photovoltaic devices. The growth of SbxSey thin films, by atmospheric pressure chemical molecular beam deposition (CMBD) method, from separate Sb and Se precursors has been reported. The conductivity of the films wa...

Sb 2 Se 3 is a promising alternative absorber material for thin-film solar cells. However, by a thermal evaporation technique, it appears to partially decompose, leading to Se deficiency. In this work, we propose two alternative routes for the supply of selenium in the deposition of Sb 2 Se 3 thin films. The first method is the co-evaporation of Se...

CdTe thin film solar cells are the most successful thin film photovoltaic devices in terms of production yield. In the last few years, by changing the original solar cell structure, the efficiency was increased from around 17 % up to 22 %. In particular two main innovations have been introduced: a CdSexTe1-x layer, that narrows the band gap of the...

Sb2Se3 thin films have received increasing interest for their applications in optoelectronics. However, technological intervention demands a material-specific understanding of the reactivity to different environments. Both thermal annealing and laser irradiation carried out in an ambient atmosphere are expected to induce changes in the pristine cry...

Cu2ZnSn(S,Se)4 solar cells were fabricated by a non-vacuum solution-based spin coating technique followed by annealing in selenium atmosphere without H2S treatment. The effects of the drying time after spin coating on physical and electrical properties of the cells were investigated. Structural and morphological properties were investigated by X-ra...

In recent years the efficiency of CdTe based solar cells has been significantly improved, mainly by the increase of the short circuit current value. This has been achieved by removing the CdS window layer and by adding a CdSexTe1-x layer, grading the band gap of the CdTe. On the other hand, ultra-thin absorbers allow to reduce the materials impact...

Over the last 20 years, the technological improvements of CdTe solar cell have been impressive, and today the performance of these cells is comparable with that of silicon cells. Behind these important results, there have been important research efforts, aimed at exploring every single aspect related to CdTe cell optimization. One of these is relia...

Citation: Vurro, F.; Jabalera, Y.; Mannucci, S.; Glorani, G.; Sola-Leyva, A.; Gerosa, M.; Romeo, A.; Romanelli, M.G.; Malatesta, M.; Calderan, L.; et al. Improving the Cellular Uptake of

CdTe is a very robust and chemically stable material and for this reason its related solar cell thin film photovoltaic technology is now the only thin film technology in the first 10 top producers in the world. CdTe has an optimum band gap for the Schockley-Queisser limit and could deliver very high efficiencies as single junction device of more th...

In instruments for low energetic neutral atom imaging of space plasmas, a charge state conversion surface (CS) is used to convert neutral atoms into ions for detection. We investigated a cadmium telluride (CdTe) coated sample as a novel material candidate regarding its suitability to be used as a CS. We measured the efficiency of converting H and O...

The goal of this paper is to investigate the stability of CdTe solar cells exposed to high temperature storage. In particular, we want to investigate the behavior of cells during short-term degradation test (up to 40 h). Several cells, having different thickness of copper in the contacts and of CdTe absorber were investigated. The results, obtained...

In the presented work, Antimony selenide (Sb2Se3) based thin films have been grown in superstrate configuration by low temperature thermal evaporation process. For re-incorporation of Se to adjust the stoichiometry and increase crystallization of the absorber has been done in this paper. Solar cells were fabricated in the superstrate configuration...

CZTS absorber films were prepared by spin-coating technique and the effect of selenization temperature on the structural and morphological properties of the CZTSSe films were studied. After confirming the phase purity of the selenized CZTS films, precursor films were also annealed in different atmosphere including sulphur and selenium+sulphur with...

The awareness of climate change is growing worldwide and with it, also the request for alternative energy solutions to fossil sources. Photovoltaic energy is one of the main answers, since the technology is well developed and can be installed anywhere. The main challenge in this field, today, is to reduce the costs of the energy produced. In this r...

Section 1. Describes the peculiarities of polycrystalline thin film materials with emphasis on CdTe and CIGS. It highlights what are the pros and cons in fabricating photovoltaic devices with these materials.

Exposure to low ozone concentrations is used in medicine as an adjuvant/complementary treatment for a variety of diseases. The therapeutic potential of low ozone concentrations relies on their capability to increase the nuclear translocation of the Nuclear factor erythroid 2-related factor 2 (Nrf2), thus inducing the transcription of Antioxidant Re...

The notion that nanoscale surfaces influence protein conformational transitions stimulates the investigation of fibrillogenic polypeptides adsorbing to nanomaterials. Alpha-synuclein (αS) is a prototypical amyloidogenic protein whose aggregation is associated with severe neurodegenerative disorders. We explored the interaction of αS with silica nan...

Alzheimer unter der Lupe: Semisynthetische und enzymbasierte Konjugationsmethoden wurden verwendet, um die Auswirkungen von Ubiquitin-Modifikationen auf die aberrante Aggregation des Tau-Proteins in neurodegenerativen Zuständen auf molekularer Ebene zu untersuchen. Abstract In the brain of individuals with Alzheimer's disease, the regulatory prote...

In the brain of individuals with Alzheimer's disease, the regulatory protein ubiquitin is found conjugated to different lysine residues of tau protein assembled into pathological paired helical filaments. To shed light on the hitherto unexplored ubiquitination‐linked conformational transitions of tau, the availability of in vitro ubiquitin conjugat...

We have fabricated ZnxSn1−xSe (ZTSe) films for the first time. Samples were fabricated by chemical molecular beam deposition method at atmospheric pressure in hydrogen flow. ZnSe and SnSe powders with 99.999% purity were used as precursors. The temperature of precursors varied in the range of (850–950) °C. Films were deposited at substrate temperat...

Flexible thin film solar cells such as CIGS, CdTe, and a-Si:H have received worldwide attention. Until now, Si solar cells dominate the photovoltaic market. Its production cost is a major concern since Si substrates account for the major cost. One way to reduce the module production cost is to use the low-cost flexible substrates. It reduces the in...

In the presented work, Antimony selenide (Sb2Se3) thin films with varying thickness (1000, 700 and 500 nm) were prepared by low temperature thermal evaporation method. Solar cells were fabricated in the superstrate configuration of Glass/ITO/ZnO/CdS/Sb2Se3/Cu/Au. Cu addition after the deposition of Sb2Se3, was introduced to improve the back contac...

Thanks to the high efficiencies achieved and to the low cost of industrial production, CdTe photovoltaic panels are still the main and most promising alternative to traditional silicon cells. In the last few years a solar cell record efficiency of 22.1 % and module efficiency of 18.6% have been achieved, but there is still room for improvement. Act...

Earth-abundancy, nontoxic constituent, along with excellent stability and optoelectronic properties make antimony selenide (Sb2Se3) one of the potential candidate for low cost photovoltaics. In this work, antimony selenide (Sb2Se3) thin films were prepared by low temperature thermal evaporation method and characterized. Solar cells were fabricated...

In this paper we propose an image segmentation method specifically designed to detect crystalline grains in microscopic images. We build on the watershed segmentation approach; we propose a preprocessing pipeline to generate a topographic map exploiting the physical nature of the incoming data (i.e. Atomic Force Microscopy) to emphasize grain bound...

In this paper, we investigate the effect of short-term thermal stresses in CdTe thin film solar cells. The CdTe solar cells under test are manufactured with physical vapour deposition on soda lime glass in superstrate configuration. Different characterization techniques were used to study the reliability of the solar cells. In particular, external...

Several Eu(III) complexes [(Eu(L1)(tta)2(H2O)]∙CF3SO3, Eu(L2)(NO3)3 and Eu(L3) with L1 = N, N′-bis(2-pyr- idylmethylidene)-1,2-(R,R+S,S)-cyclohexanediamine, L2 = N, N′-bis(2-quinolylmethylidene)- 1,2-(R,R+S,S)-cyclo- hexanediamine, L3 N-quinolyl-N,N′,N′-trans-l,2-cyclohexylenediaminetriacetic acid and tta = 2-thenoyltri- fluoroacetyl-acetonate] and...

CdTe solar cells have performed excellent efficiencies up to 22,1%. In order to reach these remarkable values it is very important to reduce or completely remove the parasitic absorbance of the CdS buffer layer. One path is to reduce the thickness and by doing so to allow the light transmittance in the low wavelength region. In this scope, ultra-th...

CdTe solar cells have shown high efficiency well above 20%. Despite different copper-free back contacts have been successfully introduced this is still required for very high efficiency devices. On the other hand an excessive amount of copper results in degradation of the device and a suitable concentration is very important for a good trade off be...

Photosystem I (PSI) is a pigment binding multi-subunit protein complex involved in the light phase of photosynthesis, catalyzing a light dependent electron transfer reaction from plastocyanin to ferredoxin. PSI is characterized by a photochemical efficiency close to one, suggesting its possible application in light dependent redox reaction in extra...

One of the crucial points in the production of CdTe solar cells is the insertion of copper in the back contact and in the absorber. As demonstrated by the top performing devices presented in literature: copper is necessary for high efficiency devices. However, despite this, copper was found to be a fast diffuser degrading the cell in the long term....

CdTe thinfilm solar cells are the most successful thinfi lm photovoltaic devices in terms of production yield, as attested by the remarkable market performance. Typically the junction is made with n-type CdS that, however, absorbs some of the light spectrum due to its band-gap of 2.4 eV. Therefore, in order to exceed 20% efficiency it is crucial to...

One of the major improvements for CdTe solar cells is the increase of the current density by enhancing the transparency of the buff er layer. CdS, with its 2.4 eV band gap, results in being opaque at low wavelength regions. For this reason, in order to gain in blue and UV light, extremely thin CdS has to be applied, if the buff er is not substitute...

Magnesium-doped Zinc Oxide (MZO) was used as an alternative high resistance transparent layer for CdS/CdTe thin film solar cells. Thin films of MZO were deposited by RF magnetron sputtering and deposited on an Indium Tin Oxide contact (ITO). Thin film CdTe devices including a MZO high resistance transparent layer deposited at above 300 • C yielded...

This work describes a novel method for the generation of a ketamine nano-delivery, to improve brain blood barrier permeability and increase drug therapeutic window as anaesthetic, analgesic and potential antidepressant. The approach herein described is based on ketamine-loaded poly-lactic-co-glycolic acid (PLGA) nanoparticles coupled to an apolipop...

CdTe photovoltaic technology is one of the first being brought into production together with amorphous silicon (already in the mid 90s Solar Cells Inc. in USA, Antec Solar and BP Solar in Europe were producing 60 × 120cm modules) and it is now the largest in production among thin film solar cells (Photovoltaics Report, 2014).CdTe has high chemical...

SnSe thin films were fabricated the first time by chemical molecular beam deposition (CMBD) in atmospheric pressure hydrogen flow using polycrystalline tin selenium (SnSe) precursors. The morphological and electrical properties of the films were studied as a function of the precursor's composition and the substrate temperature. Experimental data in...

Tin sulfide is an excellent candidate for the mass production of solar cells as it is composed of abundant and not toxic elements. We have prepared SnS polycrystalline films by a novel technique. This technology allows to transfer atoms from a target of SnS to the substrate due to the generation of plasma from the target, giving enough energy to ha...

One of the key factors for the success of CdTe solar cells is the so-called "activation" treatment, consisting in depositing a CdCl 2 film on the CdTe layer and subsequent annealing it in air. Recent studies have found MgCl 2 as a good alternative. In this work we have studied devices (exceeding 14% efficiency) prepared by low-substrate temperature...

The activation process using chlorine compounds is considered an important issue in CdTe solar cells technology. For a long time researchers have tried to replace the most successful CdCl2 activator with a non-toxic compound more suitable for industrial production. In the last years many alternatives were presented, among them the most promising is...

CdTe solar cells have shown high efficiency and the technology is scalable. As a result thin film CdTe modules are competitive with crystalline silicon modules. Thin film CdTe devices with efficiency above 22% have been reported using high substrate temperatures during the deposition process. It is known that high substrate temperatures result in l...

For CdTe solar cells copper seems to be necessary to achieve best energy conversion efficiencies, whilst it is known to be the main reason of cell performance degradation due to its tendency to diffuse through the bulk. Some studies have shown a direct connection between defect concentration and copper, but little has been discussed about its relat...

Thin film solar cells have reached commercial maturity and extraordinarily high efficiency that make them competitive even with the cheaper Chinese crystalline silicon modules. However, some issues (connected with presence of toxic and/or rare elements) are still limiting their market diffusion. For this reason new thin film materials, such as Cu 2...

For targeted brain delivery, nanoparticles (NPs) should bypass the blood-brain barrier (BBB). Novel functionalization strategies, based on low-density lipoprotein receptor (LDLR) binding domain, have been here tested to increase the brain targeting efficacy of poly D, L-lactic-co-glycolic acid (PLGA) NPs, biodegradable and suited for biomedical app...

CdTe thin film solar cells have shown to be competitive in terms of scalability and efficiency, the latest record efficiency exceeds 22%. Because of the CdTe high electron affinity the insertion of copper has demonstrated to deliver the highest efficiency device, however degrading the cell. For this reason other possible degradation effects are gen...

In this paper we present for the first time flexible CdTe solar cells deposited on ultra-thin glass using a low temperature process and compared the results to CdTe cells deposited on polyimides. The effects of the different substrates on the morphology and crystal structure of CdTe absorber layers, as well as on the efficiency of solar cells were...

Copper is a crucial element for the CdTe doping and consequently for high conversion efficiency. To analyse the effect of copper doping it is necessary to remove it from the back contact in order to avoid uncontrolled copper diffusion in the absorber. Recently, MoO3 has been successfully applied for back contact, because of its work function. In th...

The limited amount in nature of Te and In and the use of toxic elements like Cd and Se in CdTe and CuInGaSe2 solar devices (despite they have no effect on the environment) could be overcome with alternative thin films. SnS is one of the most promising materials due to its electrical and physical properties, but it is already demonstrated that high...

In recent times, new earth abundant and non toxic materials, like Cu2ZnSnS4 or SnS, have acquired a considerable interest in the photovoltaic research field. In this work, SnS thin films solar cells were prepared in superstrate configuration by vacuum evaporation of 99.99 % pure SnS compound on a glass/ITO/ZnO/CdS stack substrate heated at several...

In this paper flexible CdTe solar cells made by vacuum evaporation on ultra thin glass and on two different polyimides are presented. Ultra-thin glass is a very promising flexible substrate for CdTe solar cells in superstrate configuration because of it superior transparency. Cell preparation was optimized for each different substrate. Efficiencies...

The efficiency of CdTe solar cells with the absorber layer smaller than 1 µm is analyzed. These devices are made by decreasing the CdTe thickness from the standard 6 µm down to 350 nm. The optimization steps of our low temperature fabrication process based on physical vapor deposition. Our best efficiencies are 3.4% for device with 350 nm of CdTe a...

In the past, we described a dry process for the fabrication of CdTe/CdS thin film solar cells. In this process, most of the layers composing the cell, namely ITO, ZnO, CdS and back contact are deposited by sputtering and CdTe is deposited by close-spaced sublimation. The treatment of CdTe is done at 400 °C, for 10-20 minutes, without CdCl2, by usin...

The application of copper in the CdTe back contact is believed to be crucial to form an ohmic contact with CdTe, indeed the highest conversion efficiencies have been obtained only with copper insertion. However it is well known that the devices performance degradation with time is strongly connected to Cu presence. On the other hand it was actually...

Cadmium telluride in photovoltaics is a commercial technology that has reached the remarkable efficiency of 21 %. This continuous progress of solar cells performance puts this technology as one of the most interesting for mass production. But possible production increase would face the problem of tellurium scarcity, since it is considered a rare el...

In our laboratory we fabricate high efficiency CdTe solar cells, exceeding 15 % efficiency, with a low temperature process, where all the layers are deposited by vacuum evaporation with temperature below 450 °C. The CdCl 2 treatment is typically prepared by putting drops of a methanol solution with a specific concentration of CdCl 2. Starting from...

α-bisabolol, a natural sesquiterpene alcohol, has generated considerable interest for its anti-inflammatory activity. Since the mechanisms of this anti-inflammatory action remain poorly understood, we investigated whether α-bisabolol affects the release of pro-inflammatory cytokines IL-12, IL-23, IL-6, and TNFα by human dendritic cells (DCs). We fo...

In this paper we propose a new approach for CdTe activation treatment. Starting from a baseline of CdTe devices made with CdCl 2 activation process we present a double treatment where CdCl 2 and Freon ® , namely difluorochloromethane, treatments are applied in sequence. This new activation process delivered solar cells with efficiencies well above...

The application of copper in the CdTe back contact is believed to be crucial to form an ohmic contact with CdTe. On the other hand it has actually shown other beneficial effects such as increasing the carriers concentration, indeed the highest conversion efficiencies have been obtained only with copper insertion. However it is not clear if this is...

Cu seems to be necessary to achieve best efficiencies, however it is strongly connected with performance degradation due to its tendency to diffuse. The Cu benefits and drawbacks are still not completely clear. Other studies have shown a direct connection between Cu and defects concentration, however it is still not clear if the Cu induced degradat...

Despite CdTe solar cells have been already industrialized in large scale and modules are already available in the market, still the research for a stable, low cost, high performing back contact is very hot topic. As a matter of fact, it has been shown that the presence of copper in the CdTe device increases efficiency, not only by improving the bac...

Due to its high scalability and low production cost, CdTe solar cells have shown a very strong potential for large scale energy production. Although the number of modules produced could be limited by tellurium scarcity, it has been reported that reducing CdTe thickness down to 1.5 μm would solve this issue. There are, however, issues to be consider...

16.2% efficient Cu(In,Ga)Se2/CdS solar cells were prepared with a process which uses only sputtering and selenization. InSe, GaSe and Cu sputtering targets were used for the preparation of precursors. Selenization was done in a vacuum chamber in which pure Se is evaporated from a graphite crucible. CdS was deposited by sputtering in an atmosphere o...

CdTe has shown a significant potential for high mass production, resulting to be one of the cheapest photovoltaic technologies available. Efficiencies exceeding 17% have been obtained by the application of high temperature CdTe deposition. However a very different role of the CdCl2 activation treatment for the low and high temperature deposited CdT...

We report on the state of the art second-generation of solar cells, based on CuInGaSe2 thin film technology. These types of cells reached on the laboratory scale, photovoltaic energy conversion efficiencies of about 20,4%; this is the highest efficiency ever obtained for thin film solar cells. In particular, we describe the materials, the sequence...

CdTe solar cells are widely used in industrial production and they currently have the lowest cost per Watt available in the market thanks to its simple and scalable technology. One of the main engineering challenges for these devices is to provide a suitable back contact for CdTe due to its high electron affinity which requires a material with a ve...