Anna Belen Morales

Helmholtz-Zentrum Berlin für Materialien und Energie | HZB · PVcomB

Deposition of Nickel oxide (NiOx) by direct current (dc) magnetron sputtering of metallic & ceramic tube targets on pilot inline sputter systems. The NiOx film acts as a Hole-selective contact for PV systems.

Silicon Heterojunction has become a promising technology to substitute passivated emitter and rear contact (PERC) solar cells in pursuance of lower levelized cost of electricity through high efficiency devices. While high open circuit voltages and fill factors are reached, current loss related to the front and rear contacts, such as the transparent...

Monolithic perovskite/silicon tandem solar cells recently surpassed the efficiency of silicon single‐junction solar cells. Most tandem cells utilize >250 µm thick, planarized float‐zone (FZ) silicon, which is not compatible with commercial production using <200 µm thick Czochralski (CZ) silicon. We demonstrate perovskite/silicon tandem cells based...

Silicon heterojunction (SHJ) solar cells represent a promising technological approach towards higher photovoltaics efficiencies and lower fabrication cost. While the device physics of SHJ solar cells have been studied extensively in the past, the ways in which nanoscopic electronic processes such as charge-carrier generation, recombination, trappin...

Doped hydrogenated nanocrystalline (nc-Si:H) and silicon oxide (nc-SiOx:H) materials grown by plasma-enhanced chemical vapor deposition have favourable optoelectronic properties originated from their two-phase structure. This unique combination of qualities, initially, led to the development of thin-film Si solar cells allowing the fabrication of m...

Stable perovskites with ionic salts Ionic liquids have been shown to stabilize organic-inorganic perovskite solar cells with metal oxide carrier-transport layers, but they are incompatible with more readily processible organic analogs. Lin et al. found that an ionic solid, a piperidinium salt, enhanced the efficiency of positive-intrinsic-negative...

Monolithic [Cs0.05(MA0.17FA0.83)0.95]Pb(I0.83Br0.17)3/Cu(In,Ga)Se2 (perovskite/CIGS) tandem solar cells promise high performance and can be processed on flexible substrates, enabling cost-efficient and ultra-lightweight space photovoltaics with power-to-weight and power-to-cost ratios surpassing those of state-of-the-art III-V semiconductor-based m...

In this article, we report on the properties of indium tin oxide (ITO) deposited on thin-film silicon layers designed for the application as carrier selective contacts for silicon heterojunction (SHJ) solar cells. We find that ITO deposited on hydrogenated nanocrystalline silicon (nc-Si:H) layers presents a significant drop on electron mobility µ...

Silicon heterojunction (SHJ) solar cells rely on excellent surface passivation of the crystalline wafer. This article reports on the development of wet chemical processes varying the texturing and optimizations of the final clean processes for Czochralski–silicon wafers used in SHJ solar cells. Three different additives are used to modify both the...

Silicon heterojunction (SHJ) solar cell technology has the potential to be the next mainstream industrial solar cell design due to its high efficiency and lean production process with only four main process steps. While two-side contacted SHJ cells have very high open circuit voltages (Voc) >740 mV, they tend to be lower in short circuit current de...

Metal halide perovskites show great promise to enable highly efficient and low cost tandem solar cells when being combined with silicon. Here, we combine rear junction silicon heterojunction bottom cells with p-i-n perovskite top cells into highly efficient monolithic tandem solar cells with a certified power conversion efficiency (PCE) of 25.0 %....

In this study we make a detailed comparison between indium tin oxide (ITO), aluminum-doped zinc oxide (ZnO:Al) and hydrogenated indium oxide (IO:H) when applied on the illuminated side of rear-junction silicon heterojunction (SHJ) solar cells. ITO being the state of the art material for this application, ZnO:Al being an attractive substitute due to...

Transparent conductive oxide (TCO) layers of aluminum-doped zinc oxide (ZnO:Al) were investigated as a potential replacement of indium tin oxide (ITO) for the front contact in silicon heterojunction (SHJ) solar cells in the rear emitter configuration. It was found that ZnO:Al can be tuned to yield cell performance almost at the same level as ITO wi...

Perovskite/silicon tandem solar cells are attractive for their potential for boosting cell efficiency beyond the crystalline silicon (Si) single‐junction limit. However, the relatively large optical refractive index of Si, in comparison to that of transparent conducting oxides and perovskite absorber layers, results in significant reflection losses...

Efficient light management in monolithic perovskite/silicon tandem solar cells is one of the prerequisites for achieving high power conversion efficiencies (PCEs). Textured silicon wafers can be utilized for light management, however, this is typically not compatible with perovskite solution processing. Here, we instead employ a textured light mana...

When designing silicon heterojunction (SHJ) solar cells with a rear-emitter (RE) configuration the requirements of the conductivity of the transparent conducting oxide (TCO) at the front side are relaxed due to the contribution of lateral current flow within the silicon wafer. In this study, we analyze two approaches that can be implemented to bene...

Silicon heterojunction (SHJ) solar cells have been increasingly attracting attention to the photovoltaic community in the last years due to their high efficiency potential and the lean production process. We report on the development of a stable baseline process for SHJ cells with focus on the optical improvement of the solar cells’ front side. An...

We report on the investigation and comparison of two different processing approaches for interdigitated back contacted silicon heterojunction solar cells: our photolithography-based reference procedure and our newly developed shadow mask process. To this end, we analyse fill factor losses in different stages of the fabrication process. We find that...

Polycrystalline-silicon-on-oxide (POLO) junctions and related contacting schemes have shown their capability to facilitate high efficiencies for solar cells with passivating selective contacts [1-3]. In this work the front contacting of two-side contacted POLO cells with sputtered aluminum-doped zinc oxide (ZnO:Al) has been investigated. Different...

Hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) films have demonstrated a unique combination of low parasitic absorption and high conductivity. Here, we report on the use of n-type nc-SiOx:H as front surface field (FSF) in rear-emitter silicon heterojunction (SHJ) solar cells exhibiting excellent electrical cell parameters at a thickness dow...

The conversion efficiency of silicon heterojunction solar cells is limited by current losses mainly in the front layer stack. In order to minimize these losses, we implemented n-doped nanocrystalline silicon oxide (nc-SiOx:H) as front surface field to enhance both transparency and conductivity, thus improving the fill factor. Layers with refractive...

In this work, 50-nm thick Al2O3 thin films were deposited at room temperature by magnetron sputtering from an Al2O3 ceramic target at different RF power and argon pressure values. The sputtering technique could be preferred to conventional atomic layer deposition for an industrial application, owing to its simplicity, availability, and higher depos...

The passivation of silicon surfaces is required to reach high-efficiency with most of modern solar cell device structures. It has been demonstrated that the deposition of charged dielectric layers such a-SiNx:H or Al2O3 on the silicon surface is an efficient passivation technology. In particular, the Al2O3 material is efficient to passivate p-type...

In this work, we describe a novel fabrication process of p-type interdigitated back contact (IBC) silicon solar developed by means of laser doping and laser firing techniques. We use dielectric layers both as dopant sources to create highly-doped regions and as passivating layers. In particular, we use phosphorus-doped silicon carbide stacks (a-SiC...

In this study, we investigate the effect of the laser-firing process on the back surface passivation of p-type silicon heterojunction solar cells. For that purpose, two different nanosecond laser sources radiating at ultraviolet (UV) (355 nm) and visible (532 nm) wavelengths are employed. First, we optimize the laser-firing process in terms of the...

In this work laser doping technique is used to create highly-doped regions defined in a point-like structure to form n+/p and p+/n junctions applying a pulsed Nd-YAG 1064 nm laser in the nanosecond regime. In particular, phosphorous-doped silicon carbide stacks (a-SiCx/a-Si:H (n-type)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD)...

In this study, an approach to create laser-fired contacts from aluminum foils is studied on p-type silicon-heterojunction solar cells. This alternative approach consists of the use of aluminum foils instead of evaporated layers as a metal source and rear electrode for the laser-firing process. A q-switched infrared laser (1064 nm) was employed to c...

Laser Firing Contact (LFC) and Laser Doping (LD) have become potential alternatives to the Al BSF thermal processing conventionally used in p-type c-Si solar cell rear contacts. Optimized LFC and LD processes allow, not only the generation of efficient micro-contacts, but also the diffusion of p-type doping impurities reducing the surface recombina...

The emitter of silicon heterojunction solar cells consists of very thin hydrogenated amorphous silicon layers deposited at low temperature. The high sheet resistance of this type of emitter requires a transparent conductive oxide layer, which also acts as an effective antireflection coating. The deposition of this front electrode, typically by Sput...

In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms...

Back surface passivation is a well-known method to reduce carrier recombination and hence improves the efficiency of crystalline silicon solar cells. In this manuscript, we critically analyze the role of this process for a-Si/c-Si heterojunction solar cells through a combination of device fabrication, multiple characterization techniques, and model...

Laser Firing Contact (LFC) and Laser Doping (LD) have become potential alternatives to the Al BSF thermal processing conventionally used in p-type c-Si solar cell rear contacts. Optimized LFC and LD processes allow, not only the generation of efficient micro-contacts, but also the diffusion of p-type doping impurities reducing the surface recombina...

The aim of this work is to study the surface passivation of aluminum oxide/amorphous silicon carbide (Al2O3/a-SiCx) stacks on both p-type and n-type crystalline silicon (c-Si) substrates as well as the optical characterization of these stacks. Al2O3 films of different thicknesses were deposited by thermal atomic layer deposition (ALD) at 200 °C and...

Laser processing has been the tool of choice last years to develop improved concepts in contact formation for high efficiency crystalline silicon (c-Si) solar cells. New concepts based on standard laser fired contacts (LFC) or advanced laser doping (LD) techniques are optimal solutions for both the front and back contacts of a number of structures...

Silicon Heterojunction (SHJ) solar cells are one of the most promising alternatives for high efficiency industrially feasible solar cells. The structure of these devices is based on hydrogenated amorphous silicon (a-Si:H) layers deposited at low temperature on crystalline silicon (c-Si) substrates. This fabrication process reduces the thermal stres...

Laser Doping (LD) has become a good alternative to furnace diffusion processes typically employed for the fabrication of crystalline silicon (c-Si) solar cells. This laser technique offers a wide versatility, since it allows the creation of locally doped regions without lithography. Such doped regions can be used to generate a Back Surface Field (B...