Publications by authors named "Stefaan De Wolf"

2D perovskites and organic ligands are often implemented as passivating interlayers in perovskite solar cells. Herein, five such passivates are evaluated by using time-resolved spectroscopy to study the carrier dynamics at the perovskite-C interface. The impact of passivation on factors such as charge transfer rate, charge retention in the acceptor layers, surface recombination, and uniformity are mapped onto the solar cell performance.

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  • Researchers have tackled the challenge of crystal growth alignment in low-dimensional perovskites (LDPs) used for solar cells, specifically those with wide band gaps that hinder charge flow.
  • By adding chlorine to the precursor solution, they induced vertical crystal growth which enhances efficiency.
  • This method led to a significant power conversion efficiency of 9.4% and an open circuit voltage of 1.4V, paving the way for innovative solar applications in buildings and indoor energy solutions.
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  • * The review emphasizes the need for detailed imaging techniques to study these local property variations and their impact on device efficiency.
  • * It discusses various types of microscopy suitable for visualizing inhomogeneities in MHPs, outlining their spatial resolution, sample needs, and pros and cons to help researchers choose the right tools.
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  • Interface engineering is vital for optimizing perovskite photovoltaics (PVs), focusing on reducing unwanted recombination to improve performance.
  • A novel approach involves creating a photo-ferroelectric perovskite interface by adding an ultrathin ferroelectric layer to enhance charge separation and reduce voltage losses.
  • This innovation has achieved a record open circuit voltage of 1.21 V and a champion efficiency of 24%, demonstrating a promising direction for advanced perovskite PV designs.
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Ultrathin SiO layers and c-Si/SiO interfaces find application in tunnel-oxide passivated contacts (TOPcon) for high-efficiency silicon solar cells. Here, we investigate their detailed microscopic properties, with specific attention for the case of c-Si(100) substrates, capped either by p-type or n-type poly-silicon layers [c-Si/SiO/poly-Si (p) or c-Si/SiO/poly-Si (n)]. Our focus is on the effects of the substrate preparation conditions (either by a dry-plasma or wet SiO process) and the high-temperature annealing step (as required for the poly-Si crystallization) on the SiO stoichiometry and its microscopic structure.

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To achieve the full potential of monolithic perovskite/silicon tandem solar cells, crystal defects and film inhomogeneities in the perovskite top cell must be minimized. We discuss the use of methylenediammonium dichloride as an additive to the perovskite precursor solution, resulting in the incorporation of in situ-formed tetrahydrotriazinium (THTZ-H) into the perovskite lattice upon film crystallization. The cyclic nature of the THTZ-H cation enables a strong interaction with the lead octahedra of the perovskite lattice through the formation of hydrogen bonds with iodide in multiple directions.

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Carbon-based perovskite solar cells (PSCs) coupled with solution-processed hole transport layers (HTLs) have shown potential owing to their combination of low cost and high performance. However, the commonly used poly(3-hexylthiophene) (P3HT) semicrystalline-polymer HTL dominantly shows edge-on molecular orientation, in which the alkyl side chains directly contact the perovskite layer, resulting in an electronically poor contact at the perovskite/P3HT interface. The study adopts a synergetic strategy comprising of additive and solvent engineering to transfer the edge-on molecular orientation of P3HT HTL into 3D molecular orientation.

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Two-dimensional (2D) and three-dimensional (3D) perovskite heterostructures have played a key role in advancing the performance of perovskite solar cells. However, the migration of cations between 2D and 3D layers results in the disruption of octahedral networks, leading to degradation in performance over time. We hypothesized that perovskitoids, with robust organic-inorganic networks enabled by edge- and face-sharing, could impede ion migration.

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The photoelectrochemical (PEC) method has the potential to be an attractive route for converting and storing solar energy as chemical bonds. In this study, a maximum NH production yield of 1.01 g L with a solar-to-ammonia conversion efficiency of 8.

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Previous findings have suggested a close association between oxygen vacancies in SnO and charge carrier recombination as well as perovskite decomposition at the perovskite/SnO interface. Underlying the fundamental mechanism holds great significance in achieving a more favorable balance between the efficiency and stability. In this study, we prepared three SnO samples with different oxygen vacancy concentrations and observed that a low oxygen vacancy concentration is conducive to long-term device stability.

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Defects at the top and bottom interfaces of three-dimensional (3D) perovskite photoabsorbers diminish the performance and operational stability of perovskite solar cells owing to charge recombination, ion migration and electric-field inhomogeneities. Here we demonstrate that long alkyl amine ligands can generate near-phase-pure 2D perovskites at the top and bottom 3D perovskite interfaces and effectively resolve these issues. At the rear-contact side, we find that the alkyl amine ligand strengthens the interactions with the substrate through acid-base reactions with the phosphonic acid group from the organic hole-transporting self-assembled monolayer molecule, thus regulating the 2D perovskite formation.

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The exacerbation of inherent light scattering with increasing scintillator thickness poses a major challenge for balancing the thickness-dependent spatial resolution and scintillation brightness in X-ray imaging scintillators. Herein, a thick pixelated needle-like array scintillator capable of micrometer resolution is fabricated via waveguide structure engineering. Specifically, this involves integrating a straightforward low-temperature melting process of manganese halide with an aluminum-clad capillary template.

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  • Carbazole-based self-assembled monolayers (PACz-SAMs) are being used as effective hole-selective layers in perovskite/silicon tandem solar cells, but the impact of the microstructure of the transparent conductive oxide (TCO) on their performance has been underexplored.
  • The study found that variations in the TCO microstructure, particularly in Sn-doped InO (ITO) substrates with different grain sizes, directly affect the work function (WF) shift and local potential distribution of PACz-SAMs.
  • Amorphous TCOs, like amorphous ITO or those with an amorphous NiO layer, show a consistent surface potential, while microcr
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Radiative cooling presents a method for reducing the operational temperature of solar panels without additional energy consumption. However, its applicability to PV modules has been limited by the thermal properties of existing materials. To overcome these challenges, we introduce a V-shaped design that enhances cooling in vertical PV modules by effectively harnessing thermal radiation from both the front and rear sides, resulting in a substantial temperature reduction of 10.

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Thermally evaporated C is a near-ubiquitous electron transport layer in state-of-the-art p-i-n perovskite-based solar cells. As perovskite photovoltaic technologies are moving toward industrialization, batch-to-batch reproducibility of device performances becomes crucial. Here, we show that commercial as-received (99.

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Perovskite/silicon tandem solar cells offer a promising route to increase the power conversion efficiency of crystalline silicon (c-Si) solar cells beyond the theoretical single-junction limitations at an affordable cost. In the past decade, progress has been made toward the fabrication of highly efficient laboratory-scale tandems through a range of vacuum- and solution-based perovskite processing technologies onto various types of c-Si bottom cells. However, to become a commercial reality, the transition from laboratory to industrial fabrication will require appropriate, scalable input materials and manufacturing processes.

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Perovskite/silicon tandem solar cells have a tremendous potential to boost renewable electricity production thanks to their very high performance combined with promising cost structure. However, for actual field deployment, any solar cell technology needs to be assembled into modules, where the associated processes involve several challenges that may affect both the performance and stability of the devices. For instance, due to its hygroscopic nature, ethylene vinyl acetate (EVA) is incompatible with perovskite-based photovoltaics.

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Monolithic perovskite/silicon tandem solar cells are of great appeal as they promise high power conversion efficiencies (PCEs) at affordable cost. In state-of-the-art tandems, the perovskite top cell is electrically coupled to a silicon heterojunction bottom cell by means of a self-assembled monolayer (SAM), anchored on a transparent conductive oxide (TCO), which enables efficient charge transfer between the subcells. Yet reproducible, high-performance tandem solar cells require energetically homogeneous SAM coverage, which remains challenging, especially on textured silicon bottom cells.

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Perovskite-silicon tandem solar cells break the 30% efficiency threshold.

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With the rapid rise in device performance of perovskite solar cells (PSCs), overcoming instabilities under outdoor operating conditions has become the most crucial obstacle toward their commercialization. Among stressors such as light, heat, voltage bias, and moisture, the latter is arguably the most critical, as it can decompose metal-halide perovskite (MHP) photoactive absorbers instantly through its hygroscopic components (organic cations and metal halides). In addition, most charge transport layers (CTLs) commonly employed in PSCs also degrade in the presence of water.

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The tunable bandgaps and facile fabrication of perovskites make them attractive for multi-junction photovoltaics. However, light-induced phase segregation limits their efficiency and stability: this occurs in wide-bandgap (>1.65 electron volts) iodide/bromide mixed perovskite absorbers, and becomes even more acute in the top cells of triple-junction solar photovoltaics that require a fully 2.

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