Ana Flavia Nogueira

Two-dimensional (2D) chiral metal halide perovskites (CMHPs) emerged as promising materials for spintronics. These 2D semiconductors comprise single layers of corner-sharing metal halide octahedra (n = 1) intercalated by organic cations, which limits charge mobility and spin lifetime. In comparison, quasi-2D analogs, with two or more octahedra layers (n ≥ 2), exhibit higher charge carriers mobility, augmented spin lifetime, and tailorable bandgap. Nonetheless, the few reports on quasi-2D CMHPs in the literature often describe time-consuming synthesis and materials presenting poor chiroptical properties after processing. We address this limitation by designing heterostructure thin films comprising a chiral n = 1 phase with a non-chiral n = 2 phase. Circular dichroism (CD) manifestation in the non-chiral phase confirms chirality transfer in the heterostructures. We found that chirality transfer depends on the intermolecular interaction of the chiral and non-chiral cations, being effective when R-/S-𝛼-methylbenzylammonium (MBA) in the chiral phase is combined with benzylammonium (BZA) in the non-chiral phase. Chirality transfer is weak when n-butylammonium (BA) is used in the non-chiral phase. We attribute this difference to a more effective intermixing enabled by 𝜋-𝜋 stacking in the MBA/BZA heterostructure. This inter-phase chirality transfer strategy opens a new avenue for spintronic materials design.

The structural nature of self-assembled monolayers (SAMs) critically determines interfacial quality, film formation, and charge transport in inverted perovskite solar cells (iPSCs). While variations in SAM functional groups have been explored, these studies have focused on their impact on device performance metrics. In contrast, a fundamental understanding of how subtle molecular structural variations govern the molecular organization of SAMs, and how it modulates surface energy, interfacial properties, and the growth of perovskite films deposited atop these monolayers, remains limited. In addition, as perovskite technology advances toward industrial deployment, gaining fundamental insight into how SAMs govern film quality is essential for guiding the development of efficient and stable devices. Here, we systematically investigate the effects of SAM terminal groups (electron-withdrawing, neutral, and electron-donating) on the morphology and optoelectronic properties of perovskite films. Our results demonstrate that the electronic nature of the terminal group plays a decisive role in determining SAM molecular organization, which in turn directly affects interfacial hole extraction efficiency.

Incorporating metal-organic complexes into perovskite solar cells (PSCs) can be a suitable strategy to improve device performance via surface defects passivation with further modulation into interfacial charge-carrier dynamics. Moreover, can also enable photophysical processes like metal-to-ligand charge transfer (MLCT) and triplet-triplet annihilation (TTA), sensitizing PSCs active layer and enhancing light harvesting capability. Here, Pt(II)- and Zn(II)-based Salophen and Sal-3,4-ben complexes were employed as interfacial modifiers, with Pt(Sal-3,4-ben) yielding the most significant improvement in photovoltaic performance. Perovskite films incorporating Pt(Sal-3,4-ben) have longer charge-carrier lifetimes, as typical of strong spin-orbit coupling from the heavy Pt center and by TTA-induced charge injection into the perovskite bands. An increase in open-circuit voltage (VOC) (1.07 to 1.12 V) and in short-circuit current density (JSC) (22.18 to 24.31 mA cm-2) is observed together an improvement in fill factor and series resistance reduction. This suggests trap-state passivation and more efficient charge separation/extraction, probably arising from triplet-state processes. Involving excited triplet states may facilitate TTA or delayed fluorescence, indirectly boosting photocurrent generation originated from charge transfer process involving Pt(II) coordination compound and perovskite. In contrast, Zn-based complexes, which lack heavy atoms, exhibit limited triplet-state process resulting in modest improvements, supporting the proposed link between triplet-mediated effects and enhanced JSC. Overall, these results highlight the dual role of metal complexes in both defect passivation and photophysical tuning of PSCs, offering a new platform for exploring triplet-state and singlet-fission engineering toward higher efficiency.

Surface passivation at hybrid halide perovskite interfaces is critical for suppressing nonradiative recombination and improving operational stability, but the molecular-scale mechanisms remain incompletely understood. Here, we use density functional theory to investigate the adsorption of phenylphosphonic acid (PPA) and 2-carboxyethylphosphonic acid (CEPA) on representative surfaces CH₃NH₃PbI₃ (MAPbI₃) using periodic slab models. Both acids bind exergonically to all terminations considered, with CEPA consistently exhibiting stronger adsorption than that of PPA as a result of additional hydrogen bonding enabled by its carboxyl group. Adsorption becomes more favorable with increasing exposure to the undercoordinated surface Pb sites, consistent with Pb–O coordination as the dominant anchoring motif. Charge-density-difference analysis and atom-resolved charge partitioning reveal substantial interfacial charge redistribution, while local density-of-states calculations show adsorption-induced hybridization near the valence-band edge without introducing localized midgap states. CEPA also produces larger adsorption-induced interfacial dipoles, raising the (VBM-referenced) work-function upper bound to values above 5.9 eV. In general, these results support phosphonic acidsparticularly CEPAas effective molecular passivators that stabilize MAPbI₃ surfaces and tune interfacial energetics relevant to perovskite optoelectronic devices.

Metal halide perovskites excel under extreme space radiation but remain vulnerable to terrestrial conditions, especially thermal cycling. Advancing devices requires collaboration, interface passivation, quantum-dot integration, and in situ studies.

CuInS₂ quantum dots (QDs) have gained significant attention owing to their remarkable broadband emission, making them desirable for various optoelectronic applications requiring efficient luminescent nanomaterials. However, maximizing radiative recombination in CuInS₂ QDs necessitates minimizing intragap trap states. A common approach involves the introduction of Zn during the synthesis, which typically promotes the formation of a ZnS shell that passivates the QD surface. Despite its importance, the characterization and quantification of Zn incorporation using conventional techniques, such as optical spectroscopy or electron microscopy, remains challenging. In this study, we utilized X-ray absorption spectroscopy, in both X-ray absorption near-edge structure and extended X-ray absorption fine structure spectral ranges, to investigate Zn incorporation into CuInS₂ QDs, probing at the Zn, S, and Cu K-edges. This approach allowed us to detect the formation of a ZnS surface shell, tentatively quantifying its thickness, and to distinguish between Zn as a substituent at the shell or as an interstitial defect. Additionally, we explored the dynamical properties of CuInS₂ QDs using time-resolved optical spectroscopies, particularly in the presence of electron and hole acceptors (benzoquinone and phenothiazine), observing that hole transfer is highly sensitive to shell thickness. These results provide deeper insights into the Zn-induced shell.

This 6th annual Emerging PV Report surveys peer‐reviewed advances since August 2024 across perovskite, organic, kesterite, matildite, antimony seleno‐sulfide, selenium, and tandem solar cell architectures. Updated graphs, tables, and analyses compile the best‐performing devices from the emerging‐pv.org database, benchmarking power conversion efficiency ( PCE ), flexible photovoltaic fatigue factor ( F ), light‐utilization efficiency ( LUE ), and stability‐test energy yield (STEY) against detailed‐balance efficiency limits as functions of photovoltaic bandgap, and average visible transmittance ( AVT ) for (semi‐)transparent devices. Beyond efficiency, operational stability is assessed via degradation rates ( DR ) and t ₉₅ lifetimes. Highlights include single‐junction perovskite cells with efficiencies above 27%, organics surpassing 20%, and new Si/perovskite tandems exceeding 34%. Although multiple record efficiencies have been achieved this year, advances in mechanical robustness and operational stability remain inconsistent, especially in complex tandem stacks, emphasizing the urgent need for standardized protocols, improved large‐area homogeneity, and database‐driven benchmarks to accelerate the transition from laboratory demonstrations to scalable, real‐world deployment.