Two-dimensional/three-dimensional (2D/3D) perovskite heterojunctions at the contact interfaces have been proven to enhance the stability and power conversion efficiency (PCE) of perovskite solar cells (PSCs). The 2D/3D bilayer is typically formed via a solution post-treatment onto the 3D perovskite, where the 2D layer’s dimensionality depends on the ligand size and its reactivity. Despite their stability, long-chain ligands typically form 2D perovskites with low dimensionality ( n = 1, 2) which feature poor charge conductivity and mobility. Here, we propose an in situ fabrication method incorporating long-chain oleylammonium (OlyA + ) ligands directly into the perovskite ink. This approach forms 2D perovskite with higher dimensionalities ( n ≥ 3) with enhanced (001) crystal facet orientation of the 3D film, improved energetic alignment, charge extraction, and structural stability. The fabricated inverted PSCs with 1.55 eV bandgap achieved a maximum PCE of 26.22% for small area and 24.6% for 1cm 2 devices, as well as 21.1% for mini-modules (6.8 cm 2 ). Additionally, the PSCs with in situ formed 2D/3D perovskite heterojunctions retained 90% and 80% of their initial PCE after 1200 h photothermal stability and 1050 h outdoor testing, respectively. Our one-step strategy produces uniform and stable 2D/3D perovskite heterojunctions with enhanced passivation capability, overcoming the limitations of conventional sequential methods and offering a promising and effective approach for highly stable and efficient PSCs.

Rapid dry deposition of metal halide perovskites and inorganic scaffolds remains a key challenge for scalable vapor-phase fabrication. Here, we demonstrate fast vapor-phase growth of PbI2/CsBr inorganic scaffolds from a single composite target using pulsed laser deposition. Deposition rates exceeding 100 nm min-1, over an order of magnitude higher than comparable co-evaporated scaffolds, enable the deposition of similar to 540 nm-thick PbI2/CsBr inorganic scaffolds on textured silicon cells within 5 min. The PbI2/CsBr ratio is moreover maintained from the source target to the film, and the process delivers high material utilization. Proof-of-concept 1 cm2 fully textured perovskite/silicon tandem cells are demonstrated with the rapid PLD scaffolds converted with an organohalide solution to perovskite absorbers and passivated with piperazinium iodide. The material and device characterization demonstrates that laser-based vapor deposition is a promising route for rapid inorganic scaffold fabrication.

Multivalent, resonance-stabilized amidinium ligands enable stronger chemical coordination and reduced deprotonation compared with conventional monovalent ammonium ligands in low-dimensional perovskites. Here, we introduce a controllable one- to two-dimensional (1D-to-2D) structural transition strategy by systematically tuning ligand conformation, thereby modulating hydrogen bonding, π-π stacking, and basicity to elucidate the relationship between molecular structure, interfacial interactions, and resulting dimensionality. The 1D-amidinium perovskite structure, with its pronounced geometric anisotropy, impedes uniform surface coverage and defect passivation. In contrast, the 2D-amidinium perovskite forms a continuous, homogeneous interfacial layer, enabling more effective defect passivation and favorable energy-level alignment. With dimensionality control, inverted 3D/2D-amidinium perovskite solar cells deliver 25.4% power conversion efficiency (1.1 square centimeters, steady-state certified) and maintain >95% of their initial efficiency after 1100 hours of continuous 1-sun operation at 85°C.

Monolithic integration of perovskite solar cells (PSCs) with textured silicon is essential for commercializing perovskite/silicon tandem photovoltaics. Hybrid evaporation-solution processing enables conformal perovskite deposition on textured surfaces, but residual PbI2 at the buried interface limits performance and stability. Here, we introduce 2,4-difluorobenzamidine hydrochloride (2,4-FPhFACl) into self-assembled monolayers (SAMs) as a buried hole-selective contact to improve interface quality. The amidinium groups strongly interact with the perovskite, suppressing thermal decomposition and eliminating PbI2 formation. This approach enhances surface passivation and energy-level alignment. Wide-bandgap (1.65 eV) devices achieve a power conversion efficiency (PCE) of 20.19% and retain 80% efficiency after 2000 h at 85 degrees C. Applied to fully textured perovskite/silicon tandems, this strategy delivers a champion PCE of 29.91% (1.04 cm2), offering a scalable route to high-performance tandem photovoltaics.

The conformal coating of perovskites on textured silicon for tandem solar cells requires scalable deposition methods, for which hybrid vacuum-solution processing, using an evaporated inorganic scaffold (Pb/Cs halides) followed by solution conversion, is promising. Yet multisource coevaporation of the scaffold, as commonly used for lab-scale devices, is complex and costly to implement at an industrial scale. Here, we investigate sequential single-source evaporation of the inorganic scaffold as an industrially viable alternative. Five sequentially evaporated scaffold stacks were compared to a coevaporated reference. Despite differences in PbI2 conversion, halide distribution, and morphology, all showed similar single-junction device power conversion efficiencies (∼19%). The best scaffold (a PbI2/CsBr/PbI2/CsBr/PbI2 stack) achieved 28.4% in perovskite/silicon tandems without molecular additives, matching the coevaporated reference (28.3%). This work demonstrates that sequential deposition of the inorganic scaffold offers a scalable route to high-efficiency tandems.

Inserting two-dimensional (2D) perovskite layers at the contact interfaces of three-dimensional (3D) perovskite solar cells (PSCs) reduces surface defects and suppresses ion migration. However, these 2D layers are often inhomogeneous with excess organic ligands, jeopardizing charge extraction and device reproducibility. Here, we introduce a binary solvent post-treatment using isopropanol (IPA) and hexafluorobenzene (HFB) that selectively removes unbound ligands while promoting a homogeneous 2D perovskite layer. Guided by solubility screening and thin-film characterization, we identify an IPA:HFB composition that minimizes 2D phase dissolution while efficiently removing residual phenethylammonium iodide. Treated 2D/3D films exhibit improved optoelectronic properties. Consequently, inverted PSCs achieve a champion power-conversion efficiency of 26.10%. Accelerated thermal (ISOS-D-2) and photothermal (ISOS-L-2) stress tests show ∼67% efficiency retention after >7,200 h and ∼80% after >1,000 h, respectively. This ligand-agnostic solvent-washing strategy complements ligand-reactivity approaches and extends to other spacer cations, offering a broadly applicable route to dimensional engineering of perovskite thin films.

Perovskite photovoltaics are plagued by low stability, and achieving stable devices requires eliminating every possible source of defects. One such source is photoinduced degradation during device fabrication if incomplete devices are not kept in the dark during preparation, transfer, or storage. After perovskite deposition but before addition of the upper layers, the degradation of the incomplete devices upon illumination is caused by unbalanced charge extraction and the electric field they produce at the buried interface. This phenomenon is becoming more crucial, as passivation is now also required for the buried interface, but the passivants can be more prone to damage by the unbalanced charge extraction than the perovskite itself. Herein, we demonstrate a buried interface passivant that improves the efficiency and stability of the complete device but is highly unstable in incomplete devices. The degradation of the passivant triggers phase segregation in the perovskite itself, leading to rapid nonradiative charge recombination at the interface. The case exemplifies how slow, or blocked, electron extraction can manifest as degradation on the hole transfer side, and it is important to minimize light exposure during device preparation.

We address reverse bias instability in tin-lead perovskite solar cells by introducing Cr/Cu bilayer electrodes in their electron-selective contacts, which raise thermal breakdown voltage from -7.6 V to -14.5 V. Chromium prevents catastrophic device failure by mitigating hotspot shunting, being chemically stable against I2 formed during reverse bias stress.

Fully-textured perovskite/silicon tandem solar cells hold great promise for wide-scale photovoltaic deployment.

Perovskite/perovskite/silicon triple-junction solar cells offer notable potential for high power output at low cost, yet their development is hindered by the phase instability of perovskites, which limits both device reproducibility and performance. The ~1.50-eV formamidinium lead triiodide (FAPbI3)-based middle layer degrades during subsequent fabrication steps, and the ~2.0-eV bromide-rich top layer suffers from light-induced phase segregation. Here we address these challenges by introducing ammonium propionic acid to enhance the phase stability in both perovskite layers. This strategy raises the phase transition energy barrier and suppresses vacancy defect formation through additional bonding with lattice cations. These improvements mitigate phase instabilities and enhance the power conversion efficiency of devices based on the modified perovskite films. As a result, perovskite/perovskite/silicon triple-junction solar cells achieve a power conversion efficiency of 28.7% on a 1-cm2 aperture area, with substantially improved reproducibility.

Correction for ‘Deciphering the interplay between tin vacancies and free carriers in the ion transport of tin-based perovskites’ by Luis Huerta Hernandez et al. , Energy Environ. Sci. , 2025, 18 , 4787–4799, https://doi.org/10.1039/D5EE00632E.

Mixed ionic-electronic conduction is a prevalent phenomenon in metal halide perovskites, having a critical impact in multiple optoelectronic applications. In Sn-based halide perovskites, their higher hole density ([p]) owing to the facile formation of Sn vacancies (VSn2-) induces substantial electronic transport differences versus their Pb-based analogues. However, the influence of [p] and VSn2- on their ionic transport properties remains elusive. Herein, the link between electronic and ionic transport is unravelled in a compendium of Sn-based perovskite compositions. Specifically, ionic and electronic conductivities are found to concomitantly rise with higher Sn content. Using a combination of electrical characterization techniques, a rise in [p] and VSn2- is demonstrated to increase mobile ion density, enhancing lateral ion migration and ionic conductivity. First-principles simulations reveal that [p] and VSn2- jointly lower the energy barrier for iodide migration from 0.38 eV to 0.12 eV. Chemical mapping techniques support these observations by identifying the bias-induced migration of iodide and formamidinium ions in compositions with higher [p] and VSn2-. These fundamental insights on the ionic-electronic coupling will enable next-generation of Sn-based perovskite technologies with improved performance and stability.

Monolithic perovskite/silicon tandem solar cells have recently reached a certified record power conversion efficiency (PCE) of 34.6%. However, most of the high-efficiency tandems rely on spin coating to fabricate the perovskite absorber, which generally has limited scope for mass production. To address this, we demonstrate the potential of linear printing techniques, systematically improving 1.66 eV wide-band-gap (WBG) perovskites in single-junction perovskite solar cells (PSCs) via blade coating. Also, we enhance defect passivation and energy alignment between adjacent contacts, thus improving charge extraction in such blade-coated PSCs by introducing 2D/3D perovskite heterojunctions at their electron- and hole-collecting interfaces. Translating the 2D integrated blade-coated PSCs to our monolithic perovskite/silicon tandems significantly improved their performance, enabling an independently certified PCE of 31.2% for blade-coated tandems. Importantly, the encapsulated tandems retain 80% of their initial PCE for 1,700 h under '1-sun continuous illumination, demonstrating their durability and potential toward long-term deployment.

Reducing charge carrier transport losses, improving selectivity, and minimizing nonradiative recombination are essential for enhancing the efficiency and stability of perovskite/silicon tandem solar cells. We used a hybrid two-step perovskite deposition method that is compatible with industry-standard textured silicon, incorporating a perovskite surface treatment based on 1,3-diaminopropane dihydroiodide. The interaction of this molecule with the perovskite surface increased the majority charge carrier concentration at the electron-selective contact, which reduced interfacial recombination. Simultaneously, this field-effect passivation increased the electron concentration across the entire intrinsic perovskite absorber, which increased conductivity and reduced transport losses. Combined, this yields high-performance, fully textured perovskite/silicon tandem solar cells, achieving a 1-sun AM1.5G conversion efficiency of 33.1% with an open-circuit voltage of 2.01 volts and an extended outdoor stability in the Red Sea Coast.

Because mixed-halide wide-bandgap (1.6-2.0 eV) perovskite solar cells suffer from operating instability related to light-induced halide segregation, it is of interest to study alternative means of bandgap widening. Perovskitoids combine wide bandgaps and structural stability resulting from face- or edge-sharing octahedral connections in their crystal structures. Unfortunately, there existed no prior reports of three-dimensional (3D) perovskitoids having direct bandgaps with optical absorption edges less than 2.2 eV. As the most significant predictor of perovskitoid bandgaps is the fraction of corner-sharing in their crystal structures, we hypothesized that increasing the amount of corner-sharing would access lower bandgaps than previously reported. We accomplished this by mixing a spacer cation within the size range for 3D perovskitoid formation with a smaller perovskite-forming cation. We explored three spacer cations of different sizes: ethylammonium (EA), cyclopropylammonium (c-C3A), and cyclobutylammonium (c-C4A), combining these with methylammonium (MA), and found that the middle cation, c-C3A, pairs with MA to form a 3D perovskitoid with the formula (c-C3A)3(MA)3Pb5I16 and a direct bandgap with an optical absorption edge at 2.0 eV. Solution-processed films of this perovskitoid showed improved light stability over mixed-halide perovskites, and solar cells based on these films exhibit increased maximum power point operating stability compared to reference mixed-halide devices.

Abstract The controlled growth of two-dimensional (2D) perovskite atop three-dimensional (3D) perovskite films reduces interfacial recombination and impedes ion migration, thus improving the performance and stability of perovskite solar cells (PSCs). Unfortunately, the random orientation of the spontaneously formed 2D phase atop the pre-deposited 3D perovskite film can deteriorate charge extraction owing to energetic disorder, limiting the maximum attainable efficiency and long-term stability of the PSCs. Here, we introduce a meta-amidinopyridine ligand and the solvent post-dripping step to generate a highly ordered 2D perovskite phase on the surface of a 3D perovskite film. The reconstructed 2D/3D perovskite interface exhibits reduced energetic disorder and yields cells with improved performance compared with control 2D/3D samples. PSCs fabricated with the meta-amidinopyridine-induced phase-pure 2D perovskite passivation show a maximum power conversion efficiency of 26.05% (a certified value of 25.44%). Under damp heat and outdoor tests, the encapsulated PSCs maintain 82% and 75% of their initial PCE after 1000 h and 840 h, respectively, demonstrating improved practical durability.

Tin(IV) oxide (SnO2) thin films are commonly employed as buffer layers in p-i-n perovskite solar cells that feature transparent electron-collecting contacts, to protect underlying layers from electrode sputtering damage. While SnO2 is typically deposited via atomic layer deposition, we demonstrate here its much simpler fabrication by thermal evaporation at room temperature without any postdeposition treatment. The evaporated films exhibit oxygen deficiency that increases with film thickness. Importantly, when integrated into p-i-n solar cells, the SnO2 vacuum deposition process effectively mitigated sputtering-induced degradation during electrode deposition, retaining pristine perovskite/C60 layers. These findings establish thermally evaporated SnO2 as a viable alternative to atomic-layer-deposited counterparts for use as buffer layers in p-i-n perovskite solar cells.

The properties of layered materials are significantly dependent on their lattice orientations. Thus, the growth of graphene nanowalls (GNWs) on Cu through PECVD has been increasingly studied, yet the underlying mechanisms remain unclear. In this study, we examined the GNWs/Cu interface and investigated the evolution of their microstructure using advanced Scanning transmission electron microscopy and Electron Energy Loss Spectroscopy (STEM-EELS). GNWs interface and initial root layers of comprise graphitic carbon with horizontal basal graphene (BG) planes that conform well to the catalyst surface. In the vertical section, the walls show a mix of graphitic and turbostratic carbon, while the latter becomes more noticeable close to the top edges of the GMWs film. Importantly, we identified growth process began with catalysis at Cu interface forming BG, followed by defect induction and bending at ‘coalescence points’ of neighboring BG, which act as nucleation sites for vertical growth. We reported that although classical thermal CVD mechanism initially dominates, growth of graphene later deviates a few nanometers from the interface to form GNWs. Nascent walls are no longer subjected to the catalytic action of Cu, and their development is dominated by the stitching of charged carbon species originating in the plasma with basal plane edges.

Interface engineering is the core of device optimization, and this is particularly true for perovskite photovoltaics (PVs). The steady improvement in their performance has been largely driven by careful manipulation of interface chemistry to reduce unwanted recombination. Despite that, PVs devices still suffer from unavoidable open circuit voltage (VOC) losses. Here, we propose a different approach by creating a photo-ferroelectric perovskite interface. By engineering an ultrathin ferroelectric two-dimensional perovskite (2D) which sandwiches a perovskite bulk, we exploit the electric field generated by external polarization in the 2D layer to enhance charge separation and minimize interfacial recombination. As a result, we observe a net gain in the device VOC reaching 1.21 V, the highest value reported to date for highly efficient perovskite PVs, leading to a champion efficiency of 24%. Modeling depicts a coherent matching of the crystal and electronic structure at the interface, robust to defect states and molecular reorientation. The interface physics is finely tuned by the photoferroelectric field, representing a new tool for advanced perovskite device design.