arXiv subjects

Francesco Lodola

Publications and source records attributed to Francesco Lodola.

5 recordsLinked to original sources

arXiv2026

SciSchema.org: A Multidisciplinary Collection of Schemas for Structured Scientific Process Descriptions

Scientific processes are often described in heterogeneous article discourse, with details needed for comparison, reproducibility, reuse, and automation dispersed across prose, tables, figures, protocols, and supplementary files. We present the first release of SciSchema.org, a multidisciplinary collection of 16 expert-annotated schemas spanning Biology & Biotechnology, Materials & Chemistry, Imaging & Measurement, Physics, and Psychology. Each schema defines reusable fields for describing process instances, including inputs, outputs, materials, instruments or software, parameters, conditions, procedural steps, measurements, and provenance-related information. The schemas were created through a human-in-the-loop schema-mining workflow in which large language models generated candidate structures from process specifications, scientific articles, and expert feedback, followed by domain-expert construction of final master schemas. The dataset contains final schemas in JSON Schema and SHACL formats, intermediate model-generated schemas, expert-feedback records, source-paper metadata, community-development materials, and analysis scripts. Technical validation assessed schema structure, development provenance, expert review, and syntactic conformance. The collection supports structured annotation, metadata enrichment, scientific knowledge graphs, information extraction, semantic publishing, and cross-study comparison.

cs.DL↗

arXiv2026

What enables GaOx as hole transport layer for a 16 percent 1.0 eV CuInSe2 Bottom Cells with VOC above 550 mV?

Among the highly efficient photovoltaic technologies, that do not rely on epitaxy, only chalcopyrites have a bandgap tunable down to 1.00 eV, the ideal for tandem applications. This is obtained with a pure CuInSe2 absorber without Ga. GaOx has been shown to be an efficient hole transport layer that prevents recombination at the metallic back contact. On the other hand, GaOx has proven detrimental, when it forms on In containing transparent back contacts in bifacial solar cells. Here, we investigate the conditions that make the GaOx layer conductive. We employ a GaOx hole transport layer that is formed through ion exchange during co-evaporation of the low band gap absorber layer. We find that no additional Cu is needed, and that Na is not necessary for a conductive GaOx. Nor did we find a systematic influence of oxygen flow during the sputtering process of the oxide layer. The GaOx layer is partly crystalline. The optimized passivating hole transport layer enables a CuInSe2 bottom solar cell, without any addition of Ag or heavy alkalis, with an active area efficiency above 16% and a record-certified open-circuit voltage VOC of 552meV

cond-mat.mtrl-sci↗

arXiv2026

Loss analysis of Low Bandgap (Ag,Cu)(In,Ga)Se2 Solar Cells for Tandem Applications

Tandem solar cells can better harness the energy of the solar spectrum. Chalcopyrite solar cells have drawn attention, being the only highly efficient devices with bandgap around 1.0 eV, suitable for bottom cells. In the quest for better efficiencies, we conduct a complete loss analysis of 1.0 eV bandgap (Ag,Cu)(In,Ga)Se2 cells with efficiencies around 18.5%. We perform absolute photoluminescence, electroluminescence, JV and EQE measurements on the absorber and the finished cells to analyze losses of short-circuit current, open-circuit voltage and fill factor. The relevant losses in current are due to absorption losses in the absorber and could only be mitigated by light management structures. But the most significant losses are found in the voltage, due to non-radiative recombination in the absorber, and the fill factor, due to a high diode factor. The diode factor of the cells is significantly higher than in the absorber alone, indicating a strong influence of recombination in the space charge region.

cond-mat.mtrl-sci↗

arXiv2026

ALD Zinc Tin Oxide Buffers for Chalcopyrite Solar Cells: Electrical Barriers and Conduction Band Cliffs

Sulfide chalcopyrite, Cu(In,Ga)S2, having wide bandgap (larger than 1.5 eV), favorable optoelectronic properties, and high stability, is a promising top-cell absorber for tandem applications. Adapting device structures optimized for 1.0 - 1.2 eV absorbers to wide bandgap absorbers requires modification of the buffer layer. This work investigates atomic layer deposition of ZnSnO as an alternative buffer layer to conventional CdS. A critical parameter for bufferperformance is the conduction band offsets on both sides of the buffer. To investigate these buffers we electrically characterize solar cells utilizing different compositions of ZnSnO. The Sn/(Sn+Zn) atomic ratio is controlled by the ratio of ZnO to SnO cycles during atomic layer deposition. Solar cells were fabricated utilizing CuInSe2, Cu(In,Ga)Se2, and Cu(In,Ga)S2 absorbers, allowing cross-comparison with a variety of conduction band minimum energies. Buffer variation has two primary effects on cell performance: 1. Low tin buffers decrease the activation energy of interface recombination, reducing open circuit voltage. These observations indicates a cliff, a decrease of the conduction band minimum from absorber to buffer. 2. High tin buffers reduce the fill factor for all measured cells, and reduce the short circuit current under certain conditions. This observation indicates an electron transport barrier, conduction band offsets which limit the transport of electrons across the buffer, in either direction. We conclude that tin content correlates positively with the conduction band minimum of these buffers. Comparing different absorbers, cliffs occurs at lower Sn contents and the effects of barriers are more dramatic for absorbers with lower conduction band minima.

cond-mat.mtrl-sci↗

arXiv2025

The effect of a band gap gradient on the radiative losses in the open circuit voltage of solar cells

The radiative open circuit voltage loss in a solar cell occurs because the absorptance spectrum near the band gap shows gradual increase rather than sharp step function like transition. This broadening effect has been attributed to band gap fluctuations and or to Urbach tails. In this report, we use modelling based on Planck s generalized law to distinguish between these two effects. Our results demonstrate that Urbach tails have only a minimal effect on the absorptance edge broadening and clarify that even an ideal direct semiconductor with no band gap fluctuations shows broadening at the absorptance onset. Furthermore, state of the art inorganic thin film solar cells often incorporate a band gap gradient across their thickness, which can further contribute to absorptance broadening. Using Cu(In,Ga)Se2 (CIGSe) absorbers as a case study, we perform a comprehensive analysis of voltage losses through absolute photoluminescence and electroluminescence spectroscopy, combined with photospectrometry and high-spatial-resolution cathodoluminescence measurements. We find that the loss analysis based on the combination of radiative, generation and non-radiative losses is complete. Samples with a graded band gap profile show more pronounced broadening of the absorptance onset and up to 16 mV higher radiative losses compared to the samples with uniform band gap. There is indication, that band gap-graded samples also have larger lateral band gap inhomogeneity.

cond-mat.mtrl-sci↗