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1. The nature of silicon PN junction impedance at high frequency

Author

van Nijen, David A., Procel, Paul, van Swaaij, René A. C. M. M., Zeman, Miro, Isabella, Olindo, and Manganiello, Patrizio

Subjects
Physics - Applied Physics
Abstract

A thorough understanding of the small-signal response of solar cells can reveal intrinsic device characteristics and pave the way for innovations. This study investigates the impedance of crystalline silicon PN junction devices using TCAD simulations, focusing on the impact of frequency, bias voltage, and the presence of a low-high (LH) junction. It is shown that the PN junction exhibits a fixed $RC$-loop behavior at low frequencies, but undergoes relaxation in both resistance $R_j$ and capacitance $C_j$ as frequency increases. Moreover, it is revealed that the addition of a LH junction impacts the impedance by altering $R_j$, $C_j$, and the series resistance $R_s$. Contrary to conventional modeling approaches, which often include an additional $RC$-loop to represent the LH junction, this study suggests that such a representation does not represent the underlying physics, particularly the frequency-dependent behavior of $R_j$ and $C_j$.

Published
2024
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8. A Review: Application of Doped Hydrogenated Nanocrystalline Silicon Oxide in High Efficiency Solar Cell Devices.

Author

Qiu, Depeng, Lambertz, Andreas, Duan, Weiyuan, Mazzarella, Luana, Wagner, Philipp, Morales‐Vilches, Anna Belen, Yang, Guangtao, Procel, Paul, Isabella, Olindo, Stannowski, Bernd, and Ding, Kaining

Subjects
SILICON solar cells, SOLAR cells, SOLAR cell efficiency, SILICON oxide, BAND gaps
Abstract

Due to the unique microstructure of hydrogenated nanocrystalline silicon oxide (nc‐SiOx:H), the optoelectronic properties of this material can be tuned over a wide range, which makes it adaptable to different solar cell applications. In this work, the authors review the material properties of nc‐SiOx:H and the versatility of its applications in different types of solar cells. The review starts by introducing the growth principle of doped nc‐SiOx:H layers, the effect of oxygen content on the material properties, and the relationship between optoelectronic properties and its microstructure. A theoretical analysis of charge carrier transport mechanisms in silicon heterojunction (SHJ) solar cells with wide band gap layers is then presented. Afterwards, the authors focus on the recent developments in the implementation of nc‐SiOx:H and hydrogenated amorphous silicon oxide (a‐SiOx:H) films for SHJ, passivating contacts, and perovskite/silicon tandem devices. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Indium Reduction in Bifacial Silicon Heterojunction Solar Cells with MoOx Hole Collector.

Author

Cao, Liqi, Zhao, Yifeng, Procel Moya, Paul, Han, Can, Kovačević, Katarina, Özkol, Engin, Zeman, Miro, Mazzarella, Luana, and Isabella, Olindo

Subjects
SILICON solar cells, SOLAR cells, INDIUM oxide, ELECTRON transport, MASS production, PHOTOVOLTAIC power systems
Abstract

Reducing indium consumption in transparent conductive oxide (TCO) layers is crucial for mass production of silicon heterojunction (SHJ) solar cells. In this contribution, optical simulation‐assisted design and optimization of SHJ solar cells featuring MoOx hole collectors with ultra‐thin TCO layers is performed. Firstly, bifacial SHJ solar cells with MoOx as the hole transport layer (HTL) and three types of n‐contact as electron transport layer (ETL) are fabricated with 50 nm thick ITO on both sides. It is found that bilayer (nc‐Si:H/a‐Si:H) and trilayer (nc‐SiOx:H/nc‐Si:H/a‐Si:H) as n‐contacts performed electronically and optically better than monolayer (a‐Si:H) in bifacial SHJ cells, respectively. Then, as suggested by optical simulations, the same stack of tungsten‐doped indium oxide (IWO) and optimized MgF2 layers are applied on both sides of front/back‐contacted SHJ solar cells. Devices endowed with 10 nm thick IWO and bilayer n‐contact exhibit a certified efficiency of 21.66% and 20.66% when measured from MoOx and n‐contact side, respectively. Specifically, when illuminating from the MoOx side, the short‐circuit current density and the fill factor remain well above 40 mA cm−2 and 77%, respectively. Compared to standard front/rear TCO thicknesses (75 nm/150 nm) deployed in monofacial SHJ solar cells, this represents over 90% TCO reduction. As for bifacial cells featuring 50 nm thick IWO layers, a champion device with a bilayer n‐contact as ETL is obtained, which exhibits certified conversion efficiency of 23.25% and 22.75% when characterized from the MoOx side and the n‐layer side, respectively, with a bifaciality factor of 0.98. In general, by utilizing a n‐type bilayer stack, bifaciality factor is above 0.96 and it can be further enhanced up to 0.99 by switching to a n‐type trilayer stack. Again, compared to the aforementioned standard front/rear TCO thicknesses, this translates to a TCO reduction of more than 67%. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Comparing optical performance of a wide range of perovskite/silicon tandem architectures under real-world conditions

Author

Singh Manvika, Santbergen Rudi, Syifai Indra, Weeber Arthur, Zeman Miro, and Isabella Olindo

Subjects
bi-facial, c-si, optical modelling, perovskite, photocurrent, tandem, Physics, QC1-999
Abstract

Since single junction c-Si solar cells are reaching their practical efficiency limit. Perovskite/c-Si tandem solar cells hold the promise of achieving greater than 30% efficiencies. In this regard, optical simulations can deliver guidelines for reducing the parasitic absorption losses and increasing the photocurrent density of the tandem solar cells. In this work, an optical study of 2, 3 and 4 terminal perovskite/c-Si tandem solar cells with c-Si solar bottom cells passivated by high thermal-budget poly-Si, poly-SiOx and poly-SiCx is performed to evaluate their optical performance with respect to the conventional tandem solar cells employing silicon heterojunction bottom cells. The parasitic absorption in these carrier selective passivating contacts has been quantified. It is shown that they enable greater than 20 mA/cm2 matched implied photocurrent density in un-encapsulated 2T tandem architecture along with being compatible with high temperature production processes. For studying the performance of such tandem devices in real-world irradiance conditions and for different locations of the world, the effect of solar spectrum and angle of incidence on their optical performance is studied. Passing from mono-facial to bi-facial tandem solar cells, the photocurrent density in the bottom cell can be increased, requiring again optical optimization. Here, we analyse the effect of albedo, perovskite thickness and band gap as well as geographical location on the optical performance of these bi-facial perovskite/c-Si tandem solar cells. Our optical study shows that bi-facial 2T tandems, that also convert light incident from the rear, require radically thicker perovskite layers to match the additional current from the c-Si bottom cell. For typical perovskite bandgap and albedo values, even doubling the perovskite thickness is not sufficient. In this respect, lower bandgap perovskites are very interesting for application not only in bi-facial 2T tandems but also in related 3T and 4T tandems.

Published
2021
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16. Crystalline silicon solar cells with thin poly-SiOx carrier-selective passivating contacts for perovskite/c-Si tandem applications

Author

Singh, Manvika, Datta, Kunal, Amarnath, Aswathy, Wagner, Fabian, Zhao, Yifeng, Yang, Guangtao, Bracesco, Andrea, Phung, Nga, Zhang, Dong, Zardetto, Valerio, Najafi, Mehrdad, Veenstra, Sjoerd C., Coletti, Gianluca, Mazzarella, Luana, Creatore, Mariadriana, Wienk, Martijn M., Janssen, René A.J., Weeber, Arthur W., Zeman, Miro, Isabella, Olindo, Singh, Manvika, Datta, Kunal, Amarnath, Aswathy, Wagner, Fabian, Zhao, Yifeng, Yang, Guangtao, Bracesco, Andrea, Phung, Nga, Zhang, Dong, Zardetto, Valerio, Najafi, Mehrdad, Veenstra, Sjoerd C., Coletti, Gianluca, Mazzarella, Luana, Creatore, Mariadriana, Wienk, Martijn M., Janssen, René A.J., Weeber, Arthur W., Zeman, Miro, and Isabella, Olindo

Abstract

Single junction crystalline silicon (c-Si) solar cells are reaching their practical efficiency limit whereas perovskite/c-Si tandem solar cells have achieved efficiencies above the theoretical limit of single junction c-Si solar cells. Next to low-thermal budget silicon heterojunction architecture, high-thermal budget carrier-selective passivating contacts (CSPCs) based on polycrystalline-SiOx (poly-SiOx) also constitute a promising architecture for high efficiency perovskite/c-Si tandem solar cells. In this work, we present the development of c-Si bottom cells based on high temperature poly-SiOx CSPCs and demonstrate novel high efficiency four-terminal (4T) and two-terminal (2T) perovskite/c-Si tandem solar cells. First, we tuned the ultra-thin, thermally grown SiOx. Then we optimized the passivation properties of p-type and n-type doped poly-SiOx CSPCs. Here, we have optimized the p-type doped poly-SiOx CSPC on textured interfaces via a two-step annealing process. Finally, we integrated such bottom solar cells in both 4T and 2T tandems, achieving 28.1% and 23.2% conversion efficiency, respectively.

Published
2023

17. Optical Simulation-Aided Design and Engineering of Monolithic Perovskite/Silicon Tandem Solar Cells

Author

Zhao, Yifeng, Datta, Kunal, Phung, Nga, Bracesco, Andrea E.A., Zardetto, Valerio, Paggiaro, Giulia, Liu, Hanchen, Fardousi, Mohua, Santbergen, Rudi, Procel Moya, Paul, Han, Can, Yang, Guangtao, Wang, Junke, Zhang, Dong, van Gorkom, Bas T., van der Pol, Tom P.A., Verhage, Michael, Wienk, Martijn M., Kessels, W.M.M., Weeber, Arthur, Zeman, Miro, Mazzarella, Luana, Creatore, Mariadriana, Janssen, René A.J., Isabella, Olindo, Zhao, Yifeng, Datta, Kunal, Phung, Nga, Bracesco, Andrea E.A., Zardetto, Valerio, Paggiaro, Giulia, Liu, Hanchen, Fardousi, Mohua, Santbergen, Rudi, Procel Moya, Paul, Han, Can, Yang, Guangtao, Wang, Junke, Zhang, Dong, van Gorkom, Bas T., van der Pol, Tom P.A., Verhage, Michael, Wienk, Martijn M., Kessels, W.M.M., Weeber, Arthur, Zeman, Miro, Mazzarella, Luana, Creatore, Mariadriana, Janssen, René A.J., and Isabella, Olindo

Abstract

Monolithic perovskite/c-Si tandem solar cells have attracted enormous research attention and have achieved efficiencies above 30%. This work describes the development of monolithic tandem solar cells based on silicon heterojunction (SHJ) bottom- and perovskite top-cells and highlights light management techniques assisted by optical simulation. We first engineered (i)a-Si:H passivating layers for (100)-oriented flat c-Si surfaces and combined them with various (n)a-Si:H, (n)nc-Si:H, and (n)nc-SiOx:H interfacial layers for SHJ bottom-cells. In a symmetrical configuration, a long minority carrier lifetime of 16.9 ms was achieved when combining (i)a-Si:H bilayers with (n)nc-Si:H (extracted at the minority carrier density of 1015 cm–3). The perovskite sub-cell uses a photostable mixed-halide composition and surface passivation strategies to minimize energetic losses at charge-transport interfaces. This allows tandem efficiencies above 23% (a maximum of 24.6%) to be achieved using all three types of (n)-layers. Observations from experimentally prepared devices and optical simulations indicate that both (n)nc-SiOx:H and (n)nc-Si:H are promising for use in high-efficiency tandem solar cells. This is possible due to minimized reflection at the interfaces between the perovskite and SHJ sub-cells by optimized interference effects, demonstrating the applicability of such light management techniques to various tandem structures.

Published
2023

18. Efficient Continuous Light-Driven Electrochemical Water Splitting Enabled by Monolithic Perovskite-Silicon Tandem Photovoltaics

Author

Datta, Kunal, Branco, Bruno, Zhao, Yifeng, Zardetto, Valerio, Phung, Nga, Bracesco, Andrea, Mazzarella, Luana, Wienk, Martijn M., Creatore, Mariadriana, Isabella, Olindo, Janssen, René A.J., Datta, Kunal, Branco, Bruno, Zhao, Yifeng, Zardetto, Valerio, Phung, Nga, Bracesco, Andrea, Mazzarella, Luana, Wienk, Martijn M., Creatore, Mariadriana, Isabella, Olindo, and Janssen, René A.J.

Abstract

Solar-assisted water electrolysis is a promising technology for storing the energy of incident solar irradiation into hydrogen as a fuel. Here, an integrated continuous flow electrochemical reactor coupled to a monolithic perovskite-silicon tandem solar cell is demonstrated that provides light-driven electrochemical solar-to-hydrogen conversion with an energy conversion efficiency exceeding 21% at 1-Sun equivalent light intensity and stable operation during three simulated day-night cycles.

Published
2023

24. Passivation Enhancement of Poly-Si Carrier-Selective Contacts by Applying ALD Al_2O_3 Capping Layers

Author

Yang, Guangtao, van de Loo, Bas, Stodolny, Maciej, Limodio, Gianluca, Melskens, Jimmy, Macco, Bart, Bronsveld, Paula, Isabella, Olindo, Weeber, Arthur, Zeman, Miro, Kessels, W.M.M., Yang, Guangtao, van de Loo, Bas, Stodolny, Maciej, Limodio, Gianluca, Melskens, Jimmy, Macco, Bart, Bronsveld, Paula, Isabella, Olindo, Weeber, Arthur, Zeman, Miro, and Kessels, W.M.M.

Abstract

Hydrogenation of polycrystalline silicon (poly-Si) passivating contacts is crucial for maximizing their passivation performance. This work presents the application of Al2O3 prepared by atomic layer deposition as a hydrogenating capping layer. Several important questions related to this application of Al2O3 are addressed by comparing results from Al2O3 single layers, SiNx single layers, and Al2O3/SiNx double layers to different poly-Si types. We investigate the effect of the Al2O3 thickness, the poly-Si thickness, the poly-Si doping type, and the postdeposition annealing treatment on the passivation quality of poly-Si passivating contacts. Especially, the Al2O3/SiNx stack greatly enhances the passivation quality of both n+ and p+ doped as well as intrinsic poly-Si layers. The Al2O3 layer thickness is crucial for the single-layer approach, whereas the Al2O3/SiNx stack is less sensitive to the thickness of the Al2O3 layer. A thicker Al2O3 layer is needed for effectively hydrogenating p+ compared to n+ poly-Si passivating contact. The capping layers can hydrogenate poly-Si layers with thicknesses up to at least 600 nm. The hydrogenation-enhanced passivation for n+ poly-Si is found to be more thermally stable in comparison to p+ poly-Si. These results provide guidelines on the use of Al2O3 capping layers for poly-Si contacts to significantly improve their passivation performance.

Published
2022

26. Time-varying, ray tracing irradiance simulation approach for photovoltaic systems in complex scenarios with decoupled geometry, optical properties and illumination conditions

Author

Calcabrini Andres, Cardose Ruben, Gribnau David, Babal Pavel, Manganiello Patrizio, Zeman Miro, and Isabella Olindo

Subjects
ray tracing, spectral irradiance, Renewable Energy, Sustainability and the Environment, urban PV, tandem PV, irradiance modelling, Electrical and Electronic Engineering, Condensed Matter Physics, bifacial PV, Electronic, Optical and Magnetic Materials
Abstract

The accurate computation of the irradiance incident on the surface of photovoltaic modules is crucial for the simulation of the energy yield of a photovoltaic system. Depending on the geometrical complexity of the surroundings, different approaches are commonly employed to calculate the irradiance on the photovoltaic system. In this article, we introduce a backward ray tracing simulation approach to calculate the irradiance on photovoltaic systems in geometrically complex scenarios. We explain how the repetition of time-consuming simulation steps can be avoided with the proposed approach by storing a selection of the results from the most computationally expensive parts of the problem, and we show that the irradiance calculated with the proposed approach is in good agreement with the results of Radiance, a well-established irradiance simulation tool. Furthermore, we present an experimental validation carried out using a pyranometer and a reference cell over a period of 6 months in a complex scenario, which shows errors lower than 5% in the calculation of the daily irradiation. Finally, we compare high-resolution spectral simulations with measurements taken with a spectroradiometer under different sky conditions. The proposed approach is particularly well-suited for the simulation of bifacial and tandem photovoltaic modules in complex urban environments, for it enables the efficient simulation of high-resolution spectral irradiance in scenarios with time-varying reflectance properties.

Published
2022
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28. Three‐terminal perovskite/integrated back contact silicon tandem solar cells under low light intensity conditions

Author

Kanda, Hiroyuki, primary, Dan Mihailetchi, Valentin, additional, Gueunier‐Farret, Marie‐Estelle, additional, Kleider, Jean‐Paul, additional, Djebbour, Zakaria, additional, Alvarez, Jose, additional, Philippe, Baranek, additional, Isabella, Olindo, additional, Vogt, Malte R., additional, Santbergen, Rudi, additional, Schulz, Philip, additional, Peter, Fiala, additional, Nazeeruddin, Mohammad K., additional, and Connolly, James P., additional

Published
2022
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29. Effect of Climate on Photovoltaic Yield Prediction Using Machine Learning Models.

Author

Alcañiz, Alba, Lindfors, Anders V., Zeman, Miro, Ziar, Hesan, and Isabella, Olindo

Subjects
STANDARD deviations, PHOTOVOLTAIC power systems
Abstract

Machine learning is arising as a major solution for the photovoltaic (PV) power prediction. Despite the abundant literature, the effect of climate on yield predictions using machine learning is unknown. This work aims to find climatic trends by predicting the power of 48 PV systems around the world, equally divided into four climates. An extensive data gathering process is performed and open‐data sources are prioritized. A website www.tudelft.nl/open-source-pv-power-databases has been created with all found open data sources for future research. Five machine learning algorithms and a baseline one have been trained for each PV system. Results show that the performance ranking of the algorithms is independent of climate. Systems in dry climates depict on average the lowest Normalized Root Mean Squared Error (NRMSE) of 47.6 %, while those in tropical present the highest of 60.2 %. In mild and continental climates the NRMSE is 51.6 % and 54.5 %, respectively. When using a model trained in one climate to predict the power of a system located in another climate, on average systems located in cold climates show a lower generalization error, with an additional NRMSE as low as 5.6 % depending on the climate of the test set. Robustness evaluations were also conducted that increase the validity of the results. [ABSTRACT FROM AUTHOR]

Published
2023
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30. Innovative Floating Bifacial Photovoltaic Solutions for Inland Water Areas

Author

Ziar, Hesan, Prudon, Bjorn, Lin, Fen-Yu, Roeffen, Bart, Heijkoop, Dennis, Stark, Tim, Teurlincx, S., de Senerpont Domis, Lisette, Garcia Goma, Elias, Garro Extebarria, Julen, Narvaez Alavez, Ignacio, van Tilborg, Daniel, van Laar, Hein, Santbergen, Rudi, Isabella, Olindo, Ziar, Hesan, Prudon, Bjorn, Lin, Fen-Yu, Roeffen, Bart, Heijkoop, Dennis, Stark, Tim, Teurlincx, S., de Senerpont Domis, Lisette, Garcia Goma, Elias, Garro Extebarria, Julen, Narvaez Alavez, Ignacio, van Tilborg, Daniel, van Laar, Hein, Santbergen, Rudi, and Isabella, Olindo

Abstract

Photovoltaic (PV) technology has the potential to be integrated on many surfaces in various environments, even on water. Modeling, design, and realization of a floating PV system have more challenges than conventional rooftop or freestanding PV system. In this work, we introduce two innovative concepts for floating bifacial PV systems, describing their modeling, design, and performance monitoring. The developed concepts are retractable and enable maximum energy production through tracking the Sun. Various floating PV systems (monofacial, bifacial with and without reflectors) with different tilts and tracking capabilities are installed on a Dutch pond and are being monitored. Results of the thermal study showed that partially soaking the frame of PV modules into water does not bring a considerable additional yield (+0.17%) and revealed that floating PV modules experience higher temperature special variance compared with land‐based systems. Observations showed that the birds' presence has a severe effect on floating PV performance in the short term. Electrical yield investigation concluded that due to low albedo of inland water areas (~6.5%), bifacial PV systems must have reflectors. One‐year monitoring showed that a bifacial PV system with reflector and horizontal tracking delivers ~17.3% more specific yield (up to 29% in a clear‐sky month) compared with a monofacial PV system installed on land. Ecological monitoring showed no discernable impacts on the water quality in weekly samplings but did show significant impacts on the aquatic plant biomass and periods of low oxygen concentrations.

Published
2021

33. Transparent silicon carbide/tunnel SiO$_{2}$ passivation for c‐Si solar cell front side: Enabling J$_{sc}$ > 42 mA/cm 2 and i V$_{oc}$ of 742 mV

Author

Pomaska, Manuel, Köhler, Malte, Eberst, Alexander, Smirnov, Vladimir, Finger, Friedhelm, Rau, Uwe, Ding, Kaining, Procel Moya, Paul, Zamchiy, Alexandr, Singh, Aryak, Kim, Do Yun, Isabella, Olindo, Zeman, Miro, Li, Shenghao, and Qiu, Kaifu

Subjects
ddc:690
Abstract

N‐type microcrystalline silicon carbide (μc‐SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c‐Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc‐SiC:H(n) for c‐Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc‐SiC:H(n) on tunnel oxide (SiO2)–passivated c‐Si with an implied open‐circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm2. This excellent passivation quality is achieved directly after the HWCVD deposition of μc‐SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF2)/silicon nitride (SiNx:H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm2 with MgF2/SiNx:H/μc‐SiC:H(n) and 0.62 mA/cm2 with MgF2/μc‐SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF2/μc‐SiC:H(n)/SiO2/c‐Si as front side layer stack in an IBC solar cell reveal a short‐circuit current density of 42.2 mA/cm2, an open‐circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%.

Published
2020
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34. Efektivní pasivace povrchu černého křemíku vrstvou hydrogenizovaného amorfního křemíku naneseného pomocí plazmou podpořené depozice z plynné fáze

Author

Özkol, Engin, Procel, Paul, Zhao, Yifeng, Mazzarella, Luana, Medlín, Rostislav, Šutta, Pavol, Isabella, Olindo, and Zeman, Miro

Subjects
hydrogenizovaný amorfní křemík, conformální růst, black silicon, conformal growth, Plazmou podpořená depozice z plynné fáze, hydrogenated amorphous silicon, plasma-enhanced chemical vapor deposition, černý křemík, surface passivation, povrchová pasivace
Abstract

Solární články na bázi černého křemíku (b-Si) se ukázaly ve fotovoltaice (PV) jako nadějné a přesahující 22% účinnost. Pro dosažení vysoké účinnosti u povrchů b-Si je nejdůležitějším krokem efektivní pasivace povrchu. Dosud je nejúčinnější doba životnosti minoritních nosičů dosahována depozicí několik atomů tenké vrstvy Al2O3 nebo tepelného SiO2. Plazmou podpořená chemická depozice z par (PECVD) vrstvy hydrogenizovaného amorfního křemíku (a-Si: H) jako pasivace b-Si je jen zřídka hlášena kvůli problémům s konformitou. V této současné studii jsou b-Si povrchy superponované na standardní pyramidální textury, také známé jako modulované povrchové textury (MST), úspěšně pasivovány konformními vrstvami a-Si:H nanesenými PECVD. Je ukázáno, že za správných podmínek plazmou podpořené depozice mohou efektivní doby životnosti minoritních nosičů vzorků vybavených přední MST a zadní standardní pyramidální strukturou dosáhnout až 2,3 ms. Cesta ke konformnímu růstu je popsána a vyvinuta za pomoci transmisních elektronových mikroskopických (TEM) obrazů. Pasivované vzorky MST vykazují méně než 4% odraz v širokém spektrálním rozsahu od 430 do 1020 nm. Solar cells based on black silicon (b-Si) are proven to be promising in photovoltaics (PVs) by exceeding 22%efficiency. To reach high efficiencies with b-Si surfaces, the most crucial step is the effective surface passivation. Up to now, the highest effective minority carrier lifetimes are achieved with atomic layer-deposited Al2O3 or thermal SiO2. Plasmaenhanced chemical vapor deposition (PECVD)-grown hydrogenated amorphous silicon (a-Si:H) passivation of b-Si is seldom reported due to conformality problems. In this current study, b-Si surfaces superposed on standard pyramidal textures, also known as modulated surface textures (MSTs), are successfully passivated by PECVD-grown conformal layers of a-Si:H. It is shown that under proper plasma-processing conditions, the effective minority carrier lifetimes of samples endowed with front MST and rear standard pyramidal textures can reach up to 2.3 ms. A route to the conformal growth is described and developed by transmission electron microscopic (TEM) images. Passivated MST samples exhibit less than 4% reflection in a wide spectral range from 430 to 1020 nm.

Published
2020

35. High-Efficiency Silicon Heterojunction Solar Cells: Materials, Devices and Applications

Author

Liu, Yuqiang, Li, Yajuan, Wu, Yiliang, Yang, Guangtao, Mazzarella, Luana, Procel-Moya, Paul, Tamboli, Adele C., Weber, Klaus, Boccard, Mathieu, Isabella, Olindo, Yang, Xinbo, Sun, Baoquan, Liu, Yuqiang, Li, Yajuan, Wu, Yiliang, Yang, Guangtao, Mazzarella, Luana, Procel-Moya, Paul, Tamboli, Adele C., Weber, Klaus, Boccard, Mathieu, Isabella, Olindo, Yang, Xinbo, and Sun, Baoquan

Abstract

Photovoltaic (PV) technology offers an economic and sustainable solution to the challenge of increasing energy demand in times of global warming. The world PV market is currently dominated by the homo-junction crystalline silicon (c-Si) PV technology based on high temperature diffused p-n junctions, featuring a low power conversion efficiency (PCE). Recent years have seen the successful development of Si heterojunction technologies, boosting the PCE of c-Si solar cells over 26%. This article reviews the development status of high-efficiency c-Si heterojunction solar cells, from the materials to devices, mainly including hydrogenated amorphous silicon (a-Si:H) based silicon heterojunction technology, polycrystalline silicon (poly-Si) based carrier selective passivating contact technology, metal compounds and organic materials based dopant-free passivating contact technology. The application of silicon heterojunction solar cells for ultra-high efficiency perovskite/c-Si and III-V/c-Si tandem devices is also reviewed. In the last, the perspective, challenge and potential solutions of silicon heterojunction solar cells, as well as the tandem solar cells are discussed.

Published
2020
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39. Oxidací indukovaná transformace struktury: Tenko-vrstevní syntéza a vyšetřování rozhraní silicidu barnatého směrem k potenciálnímu využití ve fotovoltaice

Author

Tian, Yilei, Vismara, Robin, Van Doorene, Steve, Šutta, Pavol, Vančo, Ľubomír, Veselý, Marián, Vogrinčič, Peter, Isabella, Olindo, and Zeman, Miro

Subjects
žíhání, photovoltaic, Silicid barnatý, transformace struktury, interface, annealing, rozhraní, barium di-silicide, sputtering, fotovoltaika, naprašování, structure transformation
Abstract

Silicid barnatý (BaSi2) je považován za slibný absorpční materiál pro vysoko účinné tenkovrstvé solární články. Nicméně, čelí otázce související se syntézou materiálu a řízením kvality. V této práci vytváříme tenké vrstvy BaSi2 pomocí industriálně aplikovatelného procesu naprašování a odhalujeme mechanizmus strukturní transformace. Polykrystalické tenké vrstvy BaSi2 jsou získány pomocí technologie naprašování a následně tepelným zpracováním. Krystalická kvalita a fázové složení naprášených BaSi2 vrstev je posouzena Ramanovou spektroskopií a rentgenovou difrakcí (XRD). Vyšší teplota post-depozičního žíhání může podporovat krystalizaci BaSi2, avšak rovněž způsobuje intenzivní povrchovou oxidaci a difúzi na BaSi2/SiO2 rozhraní. Důsledkem toho je nehomogenní struktura vrstvy BaSi2 zjištěna Augerovou elektronovou spektroskopií (AES) a transmisní elektronovou mikroskopií (TEM). Tlustá oxidová vrstva v takto nehomogenní struktuře omezuje další, zejména optické a elektrické charakterizace naprášených BaSi2 vrstev. Proces transformace struktury naprášených BaSi2 vrstev je posléze zkoumán metodou měření hloubkového profilu Ramanové spektroskopie, přičemž všechna výše zmíněná pozorování vedou k mechanizmu oxidačně indukované transformaci mikrostruktury. To rovněž vysvětluje jev fázového rozhraní včetně povrchové oxidace a vzájemnou difúzi na rozhraní BaSi2/SiO2, což vede k nehomogenní a vrstevnaté struktuře naprášeného BaSi2. Tento mechanismus se může rovněž použít i na epitaxiální a napařované BaSi2 vrstvy. Kromě toho je prezentován i letmý pohled na další vývoj těchto materiálů a na úroveň součástek. Takové základní vědomosti o transformaci struktury a komplexní aktivity na rozhraní jsou významné pro další řízení kvality fázového rozhraní BaSi2 vrstev pro vysoko účinné solární články. Barium di-silicide (BaSi2) has been regarded as a promising absorber material for high-efficiency thin-film solar cells. However, it has confronted issues related to material synthesis and quality control. Here, we fabricate BaSi2 thin films via an industrially applicable sputtering process and uncovered the mechanism of structure transformation. Polycrystalline BaSi2 thin films are obtained through the sputtering process followed by a post-annealing treatment. The crystalline quality and phase composition of sputtered BaSi2 are characterized by Raman spectroscopy and X-ray diffraction (XRD). A higher annealing temperature can promote crystallization of BaSi2, but also causes an intensive surface oxidation and BaSi2/SiO2 interfacial diffusion. As a consequence, an inhomogeneous and layered structure of BaSi2 is revealed by Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). The thick oxide layer in such an inhomogeneous structure hinders further both optical and electrical characterizations of sputtered BaSi2. The structural transformation process of sputtered BaSi2 films then is studied by the Raman depth-profiling method, and all of the above observations come to an oxidation-induced structure transformation mechanism. It interprets interfacial phenomena including surface oxidation and BaSi2/SiO2 inter-diffusion, which lead to the inhomogeneous and layered structure of sputtered BaSi2. The mechanism can also be extended to epitaxial and evaporated BaSi2 films. In addition, a glimpse toward future developments in both material and device levels is presented. Such fundamental knowledge on structural transformations and complex interfacial activities is significant for further quality control and interface engineering on BaSi2 films toward high-efficiency solar cells.

Published
2018

47. Thin-Film Photovoltaics 2014

Author

Di Marco, Gaetano, primary, Calogero, Giuseppe, additional, Di Carlo, Aldo, additional, Lombardo, Salvatore, additional, Palmisano, Leonardo, additional, and Isabella, Olindo, additional

Published
2015
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49. Trends and gaps in photovoltaic power forecasting with machine learning

Author

Alcañiz, Alba, Grzebyk, Daniel, Ziar, Hesan, and Isabella, Olindo

Abstract

The share of solar energy in the electricity mix increases year after year. Knowing the production of photovoltaic (PV) power at each instant of time is crucial for its integration into the grid. However, due to meteorological phenomena, PV power output can be uncertain and continuously varying, which complicates yield prediction. In recent years, machine learning (ML) techniques have entered the world of PV power forecasting to help increase the accuracy of predictions. Researchers have seen great potential in this approach, creating a vast literature on the topic. This paper intends to identify the most popular approaches and the gaps in this discipline. To do so, a representative part of the literature consisting of 100 publications is classified based on different aspects such as ML family, location of PV systems, number of systems considered, features, etc. Via this classification, the main trends and gaps can be highlighted while offering advice to researchers interested in the topic.

Published
2022
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50. Solar Powered E-Bike Charging Station with AC, DC and Contactless Charging

Author

Gautham Ram Chandra Mouli, Duijsen, Peter, Velzeboer, Tim, Nair, Gireesh, Zhao, Yunpeng, Jamodkar, Ajay, Isabella, Olindo, Silvester, Sacha, Bauer, Pavol, and Zeman, Miro

Abstract

Charging electric vehicles from solar energy provides a sustainable means of transportation. This paper shows the design of solar powered e-bike charging station that provides AC, DC and contactless charging of e-bikes. The DC charger allows direct DC charging of the e-bike from the DC power of the photovoltaic panels (PV) without the need for an external AC charger adapter. In case of the contactless charger, the bike can be charged without the use of any cables providing maximum convenience to the user. Finally, the charging station has an integrated battery that allows for both grid-connected and off-grid operation

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