Hybrid vapor-solution sequential deposition of perovskites is a well-established method that enables large-area processing of perovskite films and solar cells. In this study, for the first time, we applied the hybrid sequential deposition method to the fabrication of narrow-bandgap mixed Sn-Pb perovskite films. We obtained compact, large-grained perovskite films with power conversion efficiency values exceeding 10% under 1 sun illumination with hole-transport-material-free devices. The applied method eliminates the oxidative degradation risks of solvents during perovskite formation and provides an easy way to develop additive and passivation strategies to improve photovoltaic properties.

This roadmap provides a comprehensive overview of the latest advancements in lead-free perovskite materials for photovoltaic and photoelectrochemical /photocatalytic applications. It highlights the urgent need for sustainable energy solutions, emphasizing the role of lead-free perovskites in addressing challenges related to toxicity, scalability, and efficiency. The roadmap is designed to guide the reader from application-driven perspectives to fundamental materials insights, characterization techniques, fabrication strategies and overreaching sustainability considerations. The document explores key material families, including tin-, bismuth-, antimony-, and copper-based perovskites, detailing their optoelectronic properties, fabrication techniques, and application potential. Special attention is given to advanced characterization methods, green processing strategies, the integration of artificial intelligence and machine learning for material design and optimization and lifecycle impact assessments to ensure environmental sustainability. By bringing together insights from global research communities, this roadmap serves as a strategic guide for advancing lead-free perovskite technology, fostering interdisciplinary collaboration, and accelerating the transition to next-generation solar energy solutions.

We report the preparation of MASn x Pb1-x I3 (0 <= x <= 1) thin films by three-source vapor deposition and provide the first systematic investigation of the full compositional range fabricated under identical processing conditions, enabling direct comparison across the series. Mixed perovskite formation is confirmed across all compositions, with the absorption edge red-shifting as Sn content increases. In contrast to solution-processed systems, the bandgap shows no pronounced bowing, reaching similar to 1.38 eV at low Sn compositions. Solar cells fabricated for each composition exhibit a nearly linear decrease in performance with increasing Sn fraction. Radiative-limit analysis reveals open-circuit voltage losses exceeding those expected from bandgap narrowing alone, indicating strong non-radiative recombination. Photoelectron spectroscopy reveals that Sn incorporation induces progressive p-type doping, therefore suggesting Sn oxidation in the tin-containing films. Targeted defect-control strategies and refined growth optimization during vapor deposition are therefore needed to unlock the potential of evaporated, narrow-bandgap Sn-based perovskites.

The envisaged breakthrough of perovskite photovoltaic technologies demands rapid advances in scalable and robust high-throughput fabrication methods. Here we present close-space sublimation (CSS) as a vacuum-based, industrially relevant deposition method for the conversion of sublimed PbI2 inorganic scaffolds into high-quality wide-bandgap perovskite absorbers (MAPb(I0.79Br0.21)3,1.64 eV), employing a reusable mixed-halide organic source for stable bandgap control. We provide mechanistic insights into the substitution-reaction-limited CSS process and achieve power conversion efficiencies (PCEs) of up to 18.5% for fully vacuum-processed p-i-n single-junction devices. Monolithic integration in tandem solar cells onto planar, nano-and micro-textured silicon bottom cells reveals consistent optoelectronic and morphological properties across all configurations without requiring adjustments of deposition parameters, as corroborated by comprehensive characterization techniques. The resulting perovskite/ silicon tandem solar cells reach PCEs up to 24.3%, with minimal variation across the different bottom cells. Our findings highlight the broad process window and versatility of CSS, positioning it as an industry-suitable deposition method for solvent-free high-throughput fabrication.

Vacuum deposition has emerged as a promising method for commercializing high-performance and scalable perovskite solar cells (PSCs), owing to its compatibility with large-area fabrication and tandem integration. Here, we introduce a structure-directing nanoscale layer beneath the perovskite layer to modulate interfacial interactions, suppress random island growth, and facilitate uniform perovskite growth. In situ photoluminescence measurements reveal its impact on early-stage crystallization, leading to enhanced orientation, lattice strain relaxation, and suppressed non-radiative recombination. Comprehensive analyses further confirm improved crystallinity and highly oriented crystal growth enabled by interfacial regulation. When integrated into p-i-n PSCs, the structure-directing layer significantly reduces non-radiative voltage losses, achieving a champion power conversion efficiency of 23.3%, comparable to the world record for PSCs employing co-evaporated perovskite with substantially improved stability. This work provides insights into interfacial control of perovskite crystallization and establishes structure-directing layers as an effective strategy toward scalable, efficient, and stable vacuum-deposited PSCs.

Robust, flexible, and scalable detectors for ionizing radiation are critically needed in advanced medical, environmental, and aerospace applications. Here, a polymer-perovskite composite fabricated by mechanical sintering is studied, which enables the production of thick (up to 0.5 mm) free-standing pellets. They are used in novel vertical detector architecture, with efficient charge collection, which fully exploits the large interaction volume with ionizing radiation, obtaining a low limit of detection of (37.2 +/- 1.1) nGy s(-1). The hybrid matrix ensures excellent radiation hardness and long-term operational stability preserving device properties over months. The addition of polymer not only enhances the device stability, but also confers mechanical robustness, enabling the thick perovskite-based detectors to maintain unchanged photoconductivity under extreme bending conditions (1 mm radius, >10% strain), challenging the conventional trade-off between thickness and flexibility. Additionally, we demonstrate direct detection of 5 MeV proton beam, obtaining a sensitivity of (9.3 +/- 0.2)center dot 10(-18) C/H+ with an applied electric field of 2 V & micro;m(-1). Moreover, we show the possibility of further sensitivity improvement by tuning the active layer thickness to maximize energy deposition. Overall, these results establish a scalable and conformable platform for next-generation radiation detectors, offering a unique combination of structural robustness, stability, and sensitivity to different kinds of radiation.

Photovoltaics play a key role in the renewable energy transition, where perovskite solar cells stand out as one of the most promising with high-power conversion efficiencies, desirable characteristics, and great versatility. The efficiency of these cells is mainly limited by nonradiative recombination, whether at one of the interfaces between the perovskite layer and transport layers or within the bulk of the perovskite itself. However, it is difficult to probe which of these dominates the losses during operation, which complicates further improvements. Here we introduce and demonstrate a simple, inexpensive, and easy-to-integrate method for identification of the limiting aspect of perovskite solar cells under operating conditions in terms of recombination losses. We illuminate a device with red, blue, or white light, each absorbed differently depending on the position in the device. We show that, in perovskite solar cells, the diffusion length in the bulk is of secondary importance and rather the interfaces between layers dominate the charge carrier distributions, and thus light of different wavelengths will result in changing performance. Using the fill factor from the device characteristics for each case, we are able to identify whether the front or back interface of the cell limits the performance with nearly 97% accuracy. Finally, we apply this principle experimentally using a co-evaporated perovskite solar cell, where we show a decrease of nearly 5% in fill factor depending on the wavelength of light used.

Perovskite solar cells (PSCs) are promising for high-efficiency tandem devices exceeding the Shockley-Queisser limit, whose performance is largely determined by individual subcells. A key, often overlooked factor is subcell orientation. While single-junction cells are typically optimized for bottom illumination in pin configuration, tandem applications require illumination through the top transparent electrode. Depending on the illumination direction, performance losses are dominated by nonradiative recombination either at one of the interfaces between the perovskite and transport layers or within the bulk perovskite. Identifying which of these dominates the losses remains challenging. Here, we introduce an experimental method to identify the limiting nonradiative recombination pathway and its position in bifacial PSCs. By illuminating devices from either side with red, blue, and white light, the wavelength-dependent fill factor response is used to probe the different recombination pathways. Extensive drift-diffusion simulations, varying 35 parameters and modeling a wide variety of cells, reveal characteristic fill factor traces associated with four recombination scenarios and show 95% accuracy in identifying the dominant loss mechanism using this method. Finally, the method is applied to a vapor-deposited, bifacial PSC for tandem applications, showing that the electron transport layer-perovskite interface limits the performance of this particular device.

Vacuum-deposited lead halide perovskite thin films enable solvent-free fabrication, eliminating residual processing solvents that might compromise the long-term stability. Here, we investigate the stability of thermally evaporated mixed-cation compositions FA0.8Cs0.2PbI3 and FA0.8MA0.2PbI3 (FA+ = formamidinium and MA+ = methylammonium) under thermal and light stress. Although from a thermodynamic perspective the phase stability hierarchy is typically described as MA+ < FA+ < Cs+, with Cs-based perovskites expected to be the most stable, both compositions exhibit thermal robustness, retaining their structural, optical, and morphological properties after continuous heating at 85 °C for over 500 h. Under continuous illumination, however, distinct degradation pathways emerge: FA0.8Cs0.2PbI3 shows the largest morphological and optical changes. This is attributed to chemical inhomogeneities caused by CsI-rich segregations during crystallization, which make point defects effective triggers for photodegradation. Film homogeneity improves by partially replacing iodide with bromide. Based on these results, we selected FA0.8MA0.2PbI3 and FA0.8Cs0.2Pb-(I0.8Br0.2)3 for device fabrication and evaluated their operational stability. The resulting perovskite solar cells maintain their performance after four months of outdoor operation and withstand 900 h under continuous sun-equivalent indoor illumination at room temperature. These results demonstrate how a high-quality crystallization process can reveal the potential of MA-containing perovskite formulations for long-lived perovskite photovoltaics.

The interfaces between the charge extraction layers and the perovskite layer are critical in defining the performance and stability of wide-bandgap (WBG) perovskite solar cells (PSCs). They govern multiple critical factors affecting the operation of photovoltaic devices such as the energetics of the contact, and the crystallization process of the thin film, thus its structural and electronic quality. Self-assembled monolayers (SAMs) have emerged as promising candidates as hole-selective materials for inverted PSCs, thanks to the flexibility provided by the large library of their functional groups. Herein, we outline a molecular hybridization strategy through the incorporation of the histamine molecule into the [4-(3,6-dimethyl-9H-carbazol-9yl)butyl]phosphonic acid (Me-4PACz), which is one of the most common hole extracting layers. Playing with intermolecular strong and weak interactions, we can contextually act on multiple processes. The proton transfer from the phosphonic acid group of the Me-4PACz to the ethylamine functional group of histamine enables the design of the interface dipole to facilitate hole extraction and minimize recombination losses. Then, the protonated amines balance the nucleation of halide components and stabilize the halide ions in the perovskite, avoiding their migration. Thus, three-dimensional nanovoids and tensile stress at the bottom surface were reduced, stabilizing the buried interface. Finally, the pi-pi interactions between the imidazole moiety and Me-4PACz improve the molecular assembling of the SAM, reducing disorder at the interfacial contact. The general impact of these results has been tested on PSCs based on lead mix-halide perovskites with two different bandgaps. The inverted WBG PSCs with 1.77 eV bandgap present a power conversion efficiency (PCE) of 20.34%, and maintain 95.5% of the initial PCE after 1000 hours of continuous illumination. The highly challenging WBG PSCs with 1.83 eV bandgap deliver a PCE of 18.99% with a Voc as high as 1.364 V-ranking among the highest reported PCEs and Voc values for such large bandgap.

Herein, we developed a simple approach for the fabrication of thin film inorganic perovskite and perovskite-related photoconductors. First, we synthesized CsPbBr3 and CsPb2Br5 nanoink solutions under near-ambient conditions. Next, we demonstrated the deposition of thin films with tunable properties from these nanoinks using a scalable spray-coting process with a commercial airbrush at low temperature. Eventually, the photoresponse of different films was recorded under monochromatic blue light. The photocurrent increased linearly with input power and exhibited a difference of over three orders of magnitude between photocurrent and dark current.

We present a direct route to prepare a family of MOF glasses without a meltable crystalline precursor, in contrast to the conventional melt-quenching approach. This one-step synthesis uses the linker itself as the reaction medium under an inert atmosphere, enabling the incorporation of highly hydrolytically unstable M(II) centers. This route produces high-purity iron (II) MOF glasses avoiding the oxidation and partial degradation commonly associated with the conventional melt-quenching process. The transparent glassy monoliths of formula Fe(im)2-x(bim)x, denoted as dg-MUV-29 (dg = direct-glass), can be prepared with different amounts of imidazole and benzimidazole as well as with linkers with diverse functionalities (NH2, CH3, Br, and Cl). The absence of magnetic impurities allows us to study the magnetic properties of the MOF glass itself and show that MOF glasses are good model systems for topologically-disordered amorphous antiferromagnets. We also present the functional advantages of direct-glass synthesis by creating free-standing films of glassy MOFs and integrating them in optoelectronic devices. Direct-glass synthesis is thus a powerful route to exploit the true functional potential of glassy MOFs, not only realizing further classes of MOF glasses but also unveiling properties that can be accessed with these materials.

Photoconductors are a class of photodetectors that can exhibit photoconductive gain, a key advantage for achieving high sensitivity. While most reported devices rely on lateral architectures, here we present fully vacuum-deposited vertical p-i-p perovskite photoconductors based on methylammonium lead iodide (MAPI). The influence of hole transport layers (HTLs), both intrinsic and doped, was systematically investigated. Devices incorporating intrinsic HTLs show significantly reduced dark currents, particularly when the intrinsic layer is sufficiently thick. When intrinsic and doped HTLs are combined, the devices benefit from both suppressed dark current and enhanced charge extraction, leading to superior performance. Optimized structures achieve quantum efficiency >3000% and high on/off ratio, demonstrating the potential of this vertical architecture for highly sensitive optoelectronic applications.

Indium tin oxide (ITO) is the leading transparent electrode material in displays and in photovoltaics. As both these markets are vast and rapidly expanding, the demand for alternative transparent conductive oxides (TCOs) is becoming increasingly urgent due to the limited availability of indium. Herein, aluminum-doped zinc oxide (AZO) is revisited as a promising indium-free TCO candidate. An industrial-scale pulsed laser deposition (PLD) process is developed that produces highly conductive and transparent AZO films at room temperature, without the need for post-deposition annealing. This PLD-AZO films have excellent morphological, electrical, and optical properties, with sheet resistances of approximate to 55-25 Omega Upsilon(-1) for thin TCO thicknesses (around 100 to 200 nm, respectively), and absorptance from 400 to 1000 nm below 10%. We demonstrate the application of this highly conductive PLD-AZO not only as a bottom contact but also as an effective top contact in perovskite solar cells, highlighting its versatility. The AZO-based devices achieve performance and stabilities equivalent to that of ITO-based. This findings demonstrate the robustness and potential of PLD-deposited AZO layers in enhancing displays and PV production and facilitating the wider adoption of renewable and sustainable TCO alternatives in the expanding photovoltaics and displays markets.

Controlling the sublimation of organic compounds during perovskite deposition via coevaporation is challenging. The sublimation behavior of these materials depends strongly on their purity, and their low sticking coefficient on sensors complicates deposition rate monitoring, hindering reproducibility, particularly when multiple organic sources are involved. We introduce a novel approach in which the precursor powder is pressed into a pellet, reducing material consumption and pressure fluctuation during coevaporation. This pellet can also incorporate multiple compounds, enabling, for example, the simultaneous sublimation of methyl-ammonium iodide and chloride from a single source. Combined with a Pb-(I1-x Br x )2 source, this method makes it possible to deposit triple-halide MAPIBrCl perovskite films. We confirm the incorporation of chloride in the perovskite lattice, which proves to be beneficial for the charge transport properties of the film, increasing the fill factor in wide-bandgap solar cells. Using this approach, we achieved a champion PCE of 19.5% for a 1.66 eV bandgap perovskite.

Formamidinium lead iodide perovskite compositions have a low open circuit voltage deficit and thus a higher power conversion efficiency (PCE) potential. However, their low bandgap makes it difficult to achieve a semitransparent perovskite solar cell (ST-PSC) with a high average visible transmittance (AVT) and thus, a high light utilization efficiency (LUE). Attaining a high AVT in such low bandgap perovskite‑based semitransparent solar cells requires the perovskite layer to be very thin (thickness < ≈100 nm) and the rear electrode to be made of a transparent conductive oxide. Moreover, both the front and rear electrodes should exhibit minimal reflectance losses. In this work, meeting these requirements, fully vacuum-deposited, low bandgap (≈1.55 eV, ≈100 nm thick) semitransparent perovskite solar cells are fabricated that demonstrate a high LUE value of 4.2 (PCE: 9.26% and AVT: 45.3%). Additionally, a high color rendering index of 82.4 along with a high AVT of ≈48.5% is achieved in a ST-PSC via modulation of the device reflectance by tuning both the perovskite layer thickness and the rear electrode stack. The ST‑PSCs retained > 90% of their efficiency for >1000 h when thermally stressed at 85 °C in N2 atmosphere.

Substrate temperature governs precursors adhesion, film morphology, and charge transport in vacuum-deposited perovskite films. Optimized growth at −20 °C yields efficient, thermally stable wide-bandgap perovskite solar cells.

Metal halide perovskite photodiodes have garnered extensive attention owing to their favorable optoelectronic properties, rendering them attractive for visible, near-infrared, and X-ray sensors. However, their predominant reliance on solution-processing deposition techniques poses challenges for seamless integration into existing industrial processes. In this study, this limitation is addressed by developing fully vacuum-processed perovskite photodiodes with varying hole transport layers (HTL). These findings underscore the critical role of HTL selection in influencing the dark and noise current characteristics of the diodes. With an optimized HTL, photodiodes are obtained with low noise current (approximate to 3 10-14 A Hz-1/2) and high specific detectivity (approximate to 1012 Jones at 710 nm at -0.5 V). The photodiodes are also tested as X-ray detectors and are found to be stable under X-ray radiation, with state-of-the-art sensitivity of 33 +/- 4 mu C Gy-1 cm-2 and a low limit of detection of 2.0 +/- 1.6 mu G s-1. These insights contribute to the development of perovskite photodiodes with improved performance and broader industrial applicability. Fully vacuum-processed perovskite photodiodes with varying hole transport layers (HTL) are investigated. These findings underscore the critical role of HTL selection in influencing the dark and noise current characteristics of the diodes. With an optimized HTL, photodiodes are obtained with low noise current, high specific detectivity, and state-of-the-art X-ray sensitivity. image