Gerard Masmitja

Bio: Gerard Masmitja is an academic researcher from Polytechnic University of Catalonia. The author has contributed to research in topics: Passivation & Solar cell. The author has an hindex of 8, co-authored 17 publications receiving 457 citations.

V2Ox-based hole-selective contacts for c-Si interdigitated back-contacted solar cells

Abstract: Over the last few years, transition metal oxide layers have been proposed as selective contacts both for electrons and holes and successfully applied to silicon solar cells. However, better published results need the use of both a thin and high quality intrinsic amorphous Si layer and TCO (Transparent Conductive Oxide) films. In this work, we explore the use of vanadium suboxide (V2Ox) capped with a thin Ni layer as a hole transport layer trying to avoid both the intrinsic amorphous silicon layer and the TCO contact layer. Obtained figures of merit for Ni/V2Ox/c-Si(n) test samples are saturation current densities of 175 fA cm−2 and specific contact resistance below 115 mΩ cm2 on 40 nm thick V2Ox layers. Finally, the Ni/V2Ox stack is used with an interdigitated back-contacted c-Si(n) solar cell architecture fully fabricated at low temperatures. An open circuit voltage, a short circuit current and a fill factor of 656 mV, 40.7 mA cm−2 and 74.0% are achieved, respectively, leading to a power conversion efficiency of 19.7%. These results confirm the high potential of Ni/V2Ox stacks as hole-selective contacts on crystalline silicon photovoltaics.

Interdigitated back-contacted crystalline silicon solar cells with low-temperature dopant-free selective contacts

Abstract: In the field of crystalline silicon solar cells, great efforts are being devoted to the development of selective contacts in search of a fully low-temperature and dopant-free fabrication process compatible with high photovoltaic conversion efficiencies. For high-efficiency devices, selective contacts have to simultaneously combine high conductivity with excellent passivating properties. With this objective, a thin passivating extra layer of a-Si:H or SiO2 is usually introduced between the conducting layer and the silicon substrate. In this work, we present an interdigitated back-contacted (IBC) silicon based solar cell that avoids the use of either thermal SiO2 or a-Si:H interlayers achieving a dopant-free, ITO-free and very low thermal budget fabrication process. In this work, we propose a new electron transport layer using ultrathin Al2O3/TiO2 stacks deposited by atomic layer deposition at 100 °C covered with a thermally evaporated Mg capping film. A specific contact resistance of 2.5 mΩ cm2 has been measured together with surface recombination velocities below 40 cm s−1. This electron-selective contact is combined with a thermally evaporated V2Ox-based hole selective contact to form the rear scheme of an IBC structure with a 3 × 3 cm2 active area as a proof-of-concept resulting in efficiencies beyond 19%. This approach sheds light on potential technological simplification and cost reduction in crystalline silicon solar cells.

GUANAY-II: An Autonomous Underwater Vehicle for Vertical/Horizontal Sampling

Abstract: This paper presents the design and construction of Guanay-II vehicle It is an autonomous underwater vehicle that navigates over the sea surface and, at certain fixed points, dives vertically to obtain a profile of a water column It was designed for shallow water, with maximum depth of 30 m The vehicle uses a cylinder to do the immersions The cylinder can take in and eject water smoothly, thus it can change the vehicle’s buoyancy, and avoid creating perturbations in the environment The designed vehicle has a double-hull structure The external fiberglass hull, which is not watertight, has been designed in accordance with Myring profiles to provide good hydrodynamic performance The watertight module located inside the external hull is made of aluminum and contains the immersion actuator, batteries and the electronic system to control the vehicle operations The control system is divided into several subsystems: navigation, propulsion/immersion, safety, communication and data acquisition The vehicle is 2300 mm in length by 320 mm in diameter, and weighs 90 kg

Passivating contacts for crystalline silicon solar cells

Abstract: The global photovoltaic (PV) market is dominated by crystalline silicon (c-Si) based technologies with heavily doped, directly metallized contacts. Recombination of photo-generated electrons and holes at the contact regions is increasingly constraining the power conversion efficiencies of these devices as other performance-limiting energy losses are overcome. To move forward, c-Si PV technologies must implement alternative contacting approaches. Passivating contacts, which incorporate thin films within the contact structure that simultaneously supress recombination and promote charge-carrier selectivity, are a promising next step for the mainstream c-Si PV industry. In this work, we review the fundamental physical processes governing contact formation in c-Si. In doing so we identify the role passivating contacts play in increasing c-Si solar cell efficiencies beyond the limitations imposed by heavy doping and direct metallization. Strategies towards the implementation of passivating contacts in industrial environments are discussed. The development of passivating contacts holds great potential for enhancing the power conversion efficiency of silicon photovoltaics. Here, De Wolf et al. review recent advances in material design and device architecture, and discuss technical challenges to industrial fabrication.

High-Performance TiO2 -Based Electron-Selective Contacts for Crystalline Silicon Solar Cells.

Abstract: Thin TiO2 films are demonstrated to be an excellent electron-selective contact for crystalline silicon solar cells. An efficiency of 21.6% is achieved for crystalline silicon solar cells featuring a full-area TiO2 -based electron-selective contact.

Passivating Contacts for Crystalline Silicon Solar Cells: From Concepts and Materials to Prospects

Abstract: To further increase the conversion efficiency of crystalline silicon (c-Si) solar cells, it is vital to reduce the recombination losses associated with the contacts. Therefore, a contact structure that simultaneously passivates the c-Si surface while selectively extracting only one type of charge carrier (i.e., either electrons or holes) is desired. Realizing such passivating contacts in c-Si solar cells has become an important research objective, and an overview and classification of work to date on this topic is presented here. Using this overview, we discuss the design guidelines for passivating contacts and outline their prospects.

Magnesium Fluoride Electron-Selective Contacts for Crystalline Silicon Solar Cells

Abstract: In this study, we present a novel application of thin magnesium fluoride films to form electron-selective contacts to n-type crystalline silicon (c-Si). This allows the demonstration of a 20.1%-efficient c-Si solar cell. The electron-selective contact is composed of deposited layers of amorphous silicon (∼6.5 nm), magnesium fluoride (∼1 nm), and aluminum (∼300 nm). X-ray photoelectron spectroscopy reveals a work function of 3.5 eV at the MgF2/Al interface, significantly lower than that of aluminum itself (∼4.2 eV), enabling an Ohmic contact between the aluminum electrode and n-type c-Si. The optimized contact structure exhibits a contact resistivity of ∼76 mΩ·cm(2), sufficiently low for a full-area contact to solar cells, together with a very low contact recombination current density of ∼10 fA/cm(2). We demonstrate that electrodes functionalized with thin magnesium fluoride films significantly improve the performance of silicon solar cells. The novel contacts can potentially be implemented also in organic optoelectronic devices, including photovoltaics, thin film transistors, or light emitting diodes.