Metal-halide perovskites have emerged as leading candidates for next-generation photovoltaic technologies owing to their excellent optoelectronic properties, low-cost processing, and compositional tunability. [1] Among them, tin-based perovskites are attracting increasing attention as environmentally friendly alternatives to lead-containing materials. However, their practical implementation remains hindered by critical instability mechanisms, including the oxidation of Sn²⁺ under ambient conditions and photoinduced compositional changes in mixed-halide systems. Addressing these degradation pathways is essential for the development of stable perovskite devices for real-world applications.

Here, we investigate the impact of compositional engineering on the structural, optical, and operational stability of mixed-halide tin perovskites. The stability of the mixed-halide compositions was evaluated under continuous illumination through in situ photoluminescence measurements. The investigated materials exhibit remarkable resistance to light-induced halide segregation, maintaining stable emission characteristics under illumination intensities comparable to standard operating conditions and showing only minor spectral variations at significantly higher excitation densities. These results indicate a strong suppression of photoinduced phase separation, a major limitation in many mixed-halide perovskite systems.

Ongoing studies further explore how interfacial engineering, particularly through tailored charge-transport layers, can influence halide redistribution dynamics and provide additional routes toward stabilizing mixed-halide perovskites. Together, these findings highlight synergistic compositional and interfacial approaches for enabling durable lead-free perovskite photovoltaics.

Metal halide perovskite solar cells offer a promising route toward lightweight space photovoltaics (PV) due to their high specific power, low-cost and low-temperature processing, as well as  mechanically compliant form factors. Here, we will discuss the development of ultrathin and flexible perovskite PV devices and their transition from powering terrestrial energy-autonomous systems [1, 2] to space-relevant operation [3].

Particular focus will be placed on low-Earth-orbit (LEO) testing of perovskite solar cells aboard the SSPD-1 (Space Solar Power Demonstrator 1) /ALBA mission, supported by laboratory studies under AM0 illumination, controlled temperature conditions, and high-energy proton irradiation. Structurally matched rigid and ultrathin flexible devices were evaluated in the lab from −80 to +80 °C, showing broadly reversible temperature-dependent behavior, with low-temperature losses mainly linked to transport and contact limitations rather than irreversible absorber degradation. In-operando irradiation with 68 MeV protons at a fluence of 2x1012 p+ cm-2 demonstrated strong radiation resilience, with ultrathin flexible devices retaining more than 92% of their initial efficiency after a dose equivalent to decades in LEO. In orbit, the best-performing rigid perovskite solar cell exhibited stable and reversible photoresponse during a 44-day operational window ending nearly 100 days after launch, retaining performance close to its pre-flight state despite repeated eclipse cycles and temperature variations. At the same time, the flight experiment revealed key device-level bottlenecks, including severe pre-flight environmental degradation of ultrathin flexible cells, substrate darkening, and performance losses associated with interfaces, charge-transport layers, and encapsulation. These results highlight the distinction between intrinsic perovskite radiation tolerance and full-device durability. Finally, broader challenges and opportunities for lightweight perovskite PV in space will be discussed.

The application of textured interfaces in photovoltaic devices has been a common strategy to enhance light harvesting in solar cells over the years. However, more recently, researchers have realized that, on the side, these textures can contribute to other unexpected advantages in new generation photovoltaic materials [1]. Given the potential enhancement of the wetting properties [2], crystallinity [3], charge extraction [4] and stress redistribution [5], together with the conventional optical effect, textured substrates seem ideal for the fabrication of solution processed flexible perovskite solar cells. Therefore, the implementation of textures in the appropriate flexible materials as a bottom-up strategy that individually benefits several aspects of the perovskite device can lead to an efficient, stable and resistant flexible solar cell.

In this regard, textures were implemented by two different methods on two substrate materials: hot-embossing was employed to texture ethylene tetrafluoroethylene (ETFE) while nano-imprint was applied to ultrathin polyimide (PI) before final imidization. Microscopic and stress analysis of the ITO layer revealed that textures are able to reduce crack population and propagation after bending, mitigating the degradation of the electrode performance. In ultrathin substrates, textures can help to reduce the residual stress which may impact on their reliability after delamination. Moreover, the wetting properties of textured substrates were enhanced, promoting the formation of a continuous perovskite layer. Optical performance is enhanced more than 1 mA/cm² on average compared to the planar substrates and, overall, the flexible devices provided power conversion efficiencies >25%. Finally, recent experiments have shown superior resistance of the substrate materials to proton and electron radiation compared to other common flexible materials such as polyethylene terephthalate (PET). Particularly, PI showed no degradation upon 10¹⁵ and 10¹³ of electrons and protons irradiation, respectively. These results establish them as potential candidates compatible with space environment, bringing the application of such high efficient flexible solar cells even further.

The Power Conversion Efficiency (PCE) of Organic Photovoltaics (OPV) has recently crossed the 20% milestone, placing an even larger focus on module stability, scale-up and integration into desired applications, e.g. for Building-Integrated (BIPV) or Building-Applied (BAPV) Photovoltaics. In this presentation, recent work on scalable OPV cells and modules will be presented, having a focus on Roll-to-Roll (R2R) techniques for development of scalable modules at ambient air conditions [1,2]. We demonstrate ambient air slot-die coated OPV devices reaching above 15% PCE on cell and 13% PCE on module level, as well as a new device architecture facilitating >13% PCE for ITO-free devices manufactured using solely R2R processing techniques. Stability assessment is done using ISOS protocols to shed light on the degradation processes taking place in the OPV cells and modules. The results point at interface related degradation being dominant in these OPV devices, and routes to minimize such degradation effects, at the end leading to long device lifetimes, will here be discussed in more detail [3].

Furthermore, OPV designed and developed for different specific BIPV and BAPV applications will be discussed. This is specifically development of transparent tandem photovoltaics (TPV) for window applications, developed as part CITYSOLAR project, and design and development of structural colored PV modules for the built environment, developed as part of the ColourFoil project [4]. This is achieved through the development and integration of Distributed Bragg Reflector (DBR) stacks for light management, which is utilized to tune light transmittance and reflectance in the PV modules at specific wavelength regions, to optimize for performance and/or aesthetic appearance. These DBR stacks are developed from sputtered oxide layers ensuring low surface roughness and low optical loss, and scale-up of such oxide stacks using Roll-to-Roll (R2R) processing techniques will also be demonstrated, to connect to industrial compatible manufacturing techniques and use-cases in the end.

Semitransparent organic solar cells (ST-OSCs) have gained much attention due to their potential for building-integrated photovoltaics and agrivoltaics. Since in such multi-benefit applications not only power conversion efficiency, but also average transmittance is important to achieve a high light utilization efficiency (LUE), current research focuses mostly on very thin photoactive layers to achieve significant transparency. However, thin photoactive layers are generally regarded as a challenge for large-scale industrial production, whereas over 200 nm photoactive layers provide a more robust processing window for reproducible manufacturing. In this study, we propose a strategy to decouple film transparency from film thickness by introducing polystyrene (PS) as a transparent insulator filler into the photoactive layer of PTQ10-based bulk heterojunction ST-OSCs. With approximately one-third of the photoactive layer consisting of PS, higher transmittance is achieved by optical dilution of the photoactive components in thicker films. With this approach, ST-OSCs with varying photoactive layer thickness and PS content are investigated. An increase in domain sizes caused by PS is observed, which is however overcompensated by gaining higher average transmittance at larger film thicknesses, thereby boosting the LUE of the devices with a photoactive layer thickness exceeding 150 nm and yielding an optimal LUE at around 200 nm thick photoactive layer. As a final result, PTQ10:BTP-FTh:PS based ST-OSCs with 207nm thick photoactive layers are further optimized with solutions-processed silver nanowire electrodes and achieve up to 2.8% LUE_P addressing potential agrivoltaic applications. Our proof-of-concept shows a promising way to overcome current limitations of thin-film ST-OSCs toward scalable future solar energy solutions.

Copper coordination compounds offer a uniquely tuneable platform for autonomous indoor energy systems: their redox potentials, crystallographic dimensionality, and processing routes can all be programmed at the molecular level [1]. This talk traces the complete pathway from photon absorption to on-device neural network inference through four interconnected advances in copper coordination chemistry.

We first introduce morphogenic coordination polymers in which counter-cation selection programs the crystallographic dimensionality of the semiconducting backbone. In mixed-valence Cu(II)/Cu(I) dithiocarbamate–halide systems, switching the bridging halide from bromide to iodide transforms Cu–I valence-band conjugation: the DFT-computed effective hole mass drops from 94me to 6me, conductivity rises over two orders of magnitude to 1 mS cm−1, and Arrhenius pre-exponential factors exceed those of Spiro-MeOTAD by four orders of magnitude, consistent with well-conjugated intra-chain transport limited by inter-chain hopping [2]. Deployed as dopant-free hole conductors in carbon-electrode perovskite solar cells, these polymers reach 13.8% power conversion efficiency with >94% retention over 50 days under ambient humidity.

The same coordination chemistry, in its discrete Cu(tmby)2 redox shuttle form, enables dye-sensitized solar cells (DSCs) exceeding 30% PCE under 1000 lux. Flash infrared annealing now extends these devices to ultralight 12.5 μm polyimide substrates, delivering 5.10% PCE at AM 1.5G and 255 mW g−1 specific power [3]. Monolithic integration of Cu(tmby)2-based DSCs with polyviologen/carbon asymmetric supercapacitors on a shared PEDOT electrode then closes the energy chain: three-terminal photocapacitors deliver 920 mV, 18% overall charging efficiency, and sustain battery-free edge AI for 72 hours, reaching 93% CIFAR-10 accuracy at 0.81 mJ per inference [4].

These results establish that a single family of earth-abundant coordination compounds can carry information from photon to logic gate without a battery, redefining the design space for integrated ambient energy systems.

Indoor photovoltaics (iPVs) are emerging as a key technology to power the growing Internet of Things (IoT) market. Key iPV requirements include low-cost, safe, eco-friendly materials, high efficiency under ambient light, attractive aesthetics, and compatibility with flexible electronics. Dye-sensitized solar cells (DSSCs) meet these requirements, making them promising for indoor energy harvesting [1].

Among DSSC architectures, monolithic DSSCs (M-DSSCs), which use a single transparent conductive oxide (TCO) layer substrate, offer significant advantages over conventional sandwich-type devices. By eliminating one TCO substrate, M-DSSCs reduce material costs by ~25%, enable roll-to-roll manufacturing, simplify encapsulation, and facilitate module fabrication, enhancing their potential for large-scale production [2].

In this work, monolithic DSSC modules were fabricated on thin TCO substrates (≈1.1 mm), in place of  conventional 2.2 mm-thick TCO substrates, to facilitate integration into commercial electronics. The 10×5 cm² modules comprise a mesoporous TiO₂ photoanode, a TiO₂-rutile insulating layer, a PEDOT counter electrode, and a copper-based polymer gel electrolyte prepared by photoinduced polymerization [3], using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer, and bisphenol A ethoxylate dimethacrylate (BEMA) as the crosslinking agent (1:1 wt.), with 3 wt% Irgacure® 1173 as the radical photoinitiator.

The five-cell series-connected module exhibited an open-circuit potential difference (V_OC) of 3.6 V, a short-circuit current density (J_SC) of 13.3 μA cm^-2, a maximum power point (MPP) of 23.9 μW cm^‑2, and a fill factor (ρ_FF) of 0.49, corresponding to a power conversion efficiency (ρ_PCE) of 7.5 % under 1000 lx indoor illumination (3.22 W m^-2, 2700 K LED, 60 W). To achieve output potential differences above 5 V without increasing the module footprint, each cell was laser-patterned into two electrically isolated sub-cells. The resulting ten-cell module delivered a V_OC of 7.3 V, a J_SC of 5.5 μA cm^-2, an MPP of 22.7 μW cm^‑2, an ρ_FF of 0.57, and a ρ_PCE of 8.1 %, under the same illumination conditions.

These results demonstrate that monolithic DSSC modules can deliver the output voltages required to charge low-power electronic devices while offering a scalable architecture for future IoT applications. Although further improvements in photocurrent are needed to achieve charging rates suitable for practical implementation, current efforts are directed toward fabricating these DSSC modules on ultrathin (200 μm) TCO substrates, paving the way for their integration into next-generation flexible and portable electronic devices.

The rapid expansion of the Internet of Things (IoT) is driving demand for sustainable, low-power energy solutions for distributed electronic devices, which are currently mostly powered by batteries. Indoor photovoltaics (IPVs) represent a promising alternative, enabling self-powered systems by harvesting energy from ambient indoor illumination. [1] Halide perovskites have emerged as leading candidates for IPVs due to their high absorption coefficients and tunable bandgaps.

Indoor operating conditions differ significantly from standard 1-Sun conditions, with lower photon flux and narrower light spectra. This reduces photogenerated carrier densities and increases the relative influence of recombination, leakage currents, and interfacial processes on device performance. [1] These factors strongly influence hysteresis, a phenomenon commonly attributed to ion migration, interfacial charge accumulation, and trapping. From a physical perspective, hysteresis arises from the coupling between slow ionic redistribution and fast electronic transport, resulting in time-dependent internal electric fields. In addition, hysteresis is strongly affected by measurement conditions, such as scan rate. Under solar illumination, hysteresis is expected to diminish with decreasing light intensity, as the ion-migration barrier becomes more difficult to overcome, leading to reduced ionic movement. [2,3] Our previous work showed the opposite trend under indoor conditions: hysteresis increased as illumination decreases from 1000 to 50 lx [4], challenging the widespread assumption that device behavior under 1-Sun conditions can be directly extrapolated to indoor operation.

To further investigate this phenomenon, we conducted a comprehensive study using four perovskite-based n–i–p devices incorporating either TiO₂ or SnO₂ as the electron transport layer and doped or undoped Spiro-OMeTAD as the hole transport layer. Hysteresis behavior was probed through current–voltage measurements at three illumination levels (50, 200, and 1000 lx) using varying scan rates. Complementary device simulations were performed to evaluate hysteresis as a function of scan rate and light intensity, providing insight into the underlying mechanisms. To elucidate the observations, hysteresis was decomposed into contributions from short-circuit current, open-circuit voltage, and fill factor. This approach reveals distinct hysteresis mechanisms that depend on both device architecture and operating conditions, showing that IPV hysteresis cannot be defined by a single value. These results challenge conventional hysteresis assessment approaches and highlight the need for indoor-specific characterization protocols for the reliable evaluation of IPV devices.

The past decade has witnessed a surge of interest in indoor photovoltaics (IPVs), and the opportunities they offer in sustainably powering autonomous Internet of Things (IoT) electronics [1,2]. Simultaneously, we are witnessing the exponential, pervasive rise of aritifical intelligence, which will severely test the limits of underpinning infrastructure, including electricity and water supply. An alternative paradigm is available, where rather than computing within centralised servers, computations are performed locally across a network of billions of small, autonomous nodes, much like the IoT. This is known as edge computing, or distributed intelligence, and can save on the substantial energy costs of communication, but relies on dependable and resilient local energy supplies.

In this talk, I will discuss the opportunities afforded by emerging IPV materials that now offer indoor power conversion efficiencies >35%, substantially exceeding commercial standard IPV based on hydrogenated amorphous silicon (7-16% efficiency). There are three sections. The first discusses energy requirements of edge computing, and the tiers of computatinal tasks accessible depending on the terabyte operations per second (TOPS) that can be carried out, and opportunities to improve the performance efficiency of computing units through neuromorphic devices. The second section discusses the emerging IPV technologies that are now able to provide the energy required for edge computing, the main advances that enabled these improvements, and current materials challenges that need to be addressed to further increase efficiencies towards their radiative limits. I will also discuss emerging nontoxic and stable IPV materials that also have potential for powering edge computing. Finally, I will close the loop and discuss promising energy storage solutions that can meet the high charge/discharge rates required for edge computing, and which can work in synergy with IPV to provide a reliable energy source.

Indoor photovoltaics are emerging as a promising power source for distributed electronics and Internet-of-Things devices. Compared to outdoor solar energy conversion, operation under artificial illumination imposes different requirements on photovoltaic materials, including suitable bandgaps, low non-radiative recombination losses, and efficient performance under low light intensities.¹ While lead-halide perovskites have demonstrated outstanding efficiencies, the development of efficient and sustainable lead-free alternatives remains an important challenge.

In this talk, I will discuss our efforts to develop pnictogen-based perovskite-inspired semiconductors for indoor energy harvesting. Particular emphasis will be placed on understanding how composition, defect chemistry, and microstructure influence optoelectronic properties and device performance under indoor illumination. Through examples including vacancy-ordered and alloyed bismuth-based absorbers,^2,3 A-site engineering,⁴ and related perovskite-inspired materials, I will show how compositional engineering can be used to tailor material properties and improve photovoltaic performance.

I will further demonstrate that thin-film formation and microstructure play a critical role in determining device efficiency, often becoming as important as the intrinsic properties of the absorber itself.⁵ These results highlight the importance of designing materials and processing strategies specifically for indoor operation rather than directly transferring concepts developed for conventional outdoor photovoltaics.

Finally, I will present recent advances in pnictogen-based indoor photovoltaic devices and discuss the lessons learned from translating materials optimization into device performance.^6,7 Together, these studies highlight both the opportunities and the remaining challenges for pnictogen-based semiconductors in low-light energy harvesting and sustainable self-powered electronics.

The surging demand for sustainable energy has accelerated the development of transparent photovoltaics (TPVs), expanding their utility from terrestrial surfaces to aquatic environments [1-2]. Here, we present the development and performance analysis of a transparent energy device based on advanced materials with high optical transmittance and efficient energy conversion capabilities. The fabricated device maintains excellent transparency while delivering significant energy output, demonstrating strong potential for integration into everyday surfaces such as glass façades and mobile displays. These findings highlight the promising future of transparent energy systems as a core technology for next-generation smart cities and zero-energy buildings.

Owing to their transparency and self-powered functionality, TPV devices offer expanded opportunities for diverse applications, including smart power transfer, healthcare, and sustainable bioelectronic systems. While conventional underwater photovoltaics suffer from poor light coupling, this work demonstrates a water-enhanced TPV module based on a wide-bandgap heterojunction designed for efficient submerged power generation [3,4,5]. In this configuration, the surrounding water medium passively acts as an optical concentrator, enhancing light coupling and widening the angular light-collection range. Beyond this passive mechanism, we introduce an active energy-harvesting route by tuning the polarity of the water-layer interface. This engineered interaction induces a robust, localized electric field that substantially enhances the light-reactive performance of the device. This innovative "underwater power window" provides a highly sustainable, self-powered energy solution tailored for marine sensing, communication, and deep-submerged applications.

[1] Mohan More, V.; Patel, M.; Cho, S.; Lee, J.; Cho, Y.; Kim, J. Hybrid Pyroelectric-Photovoltaic Devices for High-Efficiency Underwater Optoelectronics. Nano Energy 2026 (https://doi.org/10.1016/j.nanoen.2026.112212)

[2] Patel, M.; Park, H.-H.; Bhatnagar, P.; Kumar, N.; Lee, J.; Kim, J. Transparent Integrated Pyroelectric-Photovoltaic Structure for Photo-Thermo Hybrid Power Generation. Nat. Commun. 2024, 15, 3466.

[3] Vo Thi, S.; Patel, M.; Lee, J.; Hossain, S.; Barno, M. A. R.; Kim, J. Water-Enabled Enhancement of Transparent Schottky Photodetectors. Nanoscale 2026, 18, 4712−4719.

[4] Patel, M.; Nguyen, T. T.; Park, H.-H.; Cho, S.; Yun, S.; Kumar, N.; Ghosh, S.; Kim, J. Transparent Underwater Power Windows: Enhanced Light Management and Harvesting with Water-Embedded Wide-Bandgap Heterojunction Photovoltaics for Sustainable Energy. Nano Energy 2025, 142, 111239.

[5] Patel, M.; Barno, M. A. R.; Barichello, J.; Vo Thi, S.; Cho, S.; Matteocci, F.; Di Carlo, A.; Wong, C.-P.; Kim, J. Water-Driven Photovoltaics: Enhancing Performance through Water Media in the Active Layer. Mater. Today Sustainability 2025, 31, 101158.

Photovoltaic (PV) technologies are increasingly deployed beyond conventional terrestrial settings, where light intensity and spectral distribution deviate markedly from standard AM1.5G conditions^[1]. Underwater environments represent a prime example, characterized by severe light attenuation, depth-dependent spectral narrowing, and a shift in demand toward low-power electronics rather than grid-scale generation^[2]. Consequently, the core objective must shift from a singular pursuit of maximum terrestrial efficiency to identifying PV platforms that deliver reliable power under these aquatic constraints.

Moving beyond conventional device optimization, this study evaluates how perovskite compositions, optical responses, and architectures can be tailored to match the unique underwater spectrum^[3]. Due to their exceptional visible-light absorption and intrinsic bandgap tunability, perovskites offer a strategic advantage in these spectrally selective environments over traditional PV technologies that were originally optimized for the full solar spectrum^[4-5].

To bridge the gap between material properties and practical utility, we extend the investigation to field related application verification by coupling perovskite modules with energy storage and low-power submerged mnitor. Real-world aquatic testing validates the feasibility of these integrated units to drive functional, self-powered sensing platforms. Ultimately, this work establishes a design paradigm that prioritizes environmental compatibility and system integration over raw material records for next-generation photovoltaics.

Large-scale flexible photovoltaics, including organic photovoltaics (OPV) and perovskite photovoltaics (PPV), have gained increasing attention in recent years due to their potential for low-cost manufacturing and unique advantages such as mechanical flexibility, lightweight design, and semi-transparency. These properties enable new application fields beyond conventional photovoltaics, including building-integrated photovoltaics (BIPV). Roll-to-roll (R2R) printing offers a highly scalable manufacturing approach, allowing rapid fabrication of large-area thin-film modules on flexible substrates.

However, transferring high-performing laboratory-scale devices into industrially relevant module sizes remains a major challenge. Performance losses during upscaling, as well as stability limitations, continue to represent key barriers for market introduction. In this contribution, we present strategies to minimize upscaling losses by transferring advanced OPV and PPV material systems and device architectures to flexible substrates using industrially relevant printing processes.

For R2R-printed PPV, we demonstrate recent advances achieved through optimized perovskite precursor formulations, enabling high efficiencies and improved operational stability under ambient production conditions. For OPV, a detailed analysis of the performance losses during scale-up from 0.1 cm² laboratory cells to 210 cm² R2R-printed modules is presented. Furthermore, the optical properties of the module stacks can be tailored over a broad range of transparencies, enabling application-specific optimization from high-efficiency modules for façade integration to highly transparent solutions for photovoltaic windows.

Comprehensive lifetime studies complete the assessment and highlight remaining challenges and pathways towards reducing market entry barriers for large-scale flexible photovoltaics.

Quantum cutting in Yb-doped lead halide perovskites has attracted considerable interest as a route to spectral conversion, with the potential to transform a single ultraviolet or visible photon into two near-infrared photons suitable for silicon photovoltaics.[1,2] Detailed balance calculations indicate that quantum cutting could significantly increase the theoretical efficiency limit of single-junction solar cells, but does not substantially improve the efficiency limit of tandem solar cells.[3] Even so, spectral shaping via quantum cutting provides several unique opportunities for tandems, broadening the range of optimal top-cell bandgaps from 1.7 eV to 1.45 eV depending on the quantum cutting bandgap. This opens the possibility of employing more stable neat-iodide perovskite absorbers while potentially improving ultraviolet utilization through improved external quantum efficiency.

To evaluate the practical feasibility of this approach, we combined experimental measurements with density functional theory calculations to investigate the reproducibility of quantum cutting in Yb-doped halide perovskites. Near-infrared down-conversion was consistently observed across multiple halide compositions and Yb concentrations, reproducing both the bandgap threshold for efficient down-conversion and optimal Yb concentration.[4] However, we did not observe photoluminescence quantum yields above 100%, suggesting that reproducible quantum cutting is not achieved under the conditions examined.

Density functional theory calculations were used to probe the local defect chemistry underlying this behavior. While isolated Yb-related defect complexes at low dopant concentrations can, in principle, support quantum cutting, these configurations are not strongly favored thermodynamically. Instead, Yb clustering becomes increasingly favorable, producing asymmetrical mid-gap electronic states that suppress quantum cutting.

These combined experimental and computational results indicate that although quantum cutting remains physically plausible in Yb-doped lead halide perovskites, its realization is highly sensitive to the local dopant environment and is therefore not intrinsically reproducible. Future progress will likely require strategies that control local defect configurations, including co-doping, defect engineering, or alternative synthetic approaches.

Metal-halide perovskite solar cells (PSCs) are promising candidates for lightweight, high-specific-power photovoltaic systems intended for operation in radiation-rich environments.[1,2] While numerous studies have demonstrated a degree of radiation tolerance in PSCs [3-5], the influence of device architecture and electrode configuration on radiation-induced degradation remains insufficiently understood. Identifying design strategies that enhance radiation hardness is therefore critical for the development of perovskite photovoltaics for aerospace applications.

In this work, we investigate the impact of device architecture and bifacial design on the radiation response of PSCs subjected to heavy-ion irradiation. PSCs employing both n-i-p and p-i-n configurations were exposed to krypton ions (Kr-ion energy: 1.75 MeV; Fluence: 10¹⁰-10¹¹ nucleons/cm²). In addition, conventional monofacial cells with opaque metallic rear electrodes are compared with bifacial devices incorporating transparent rear contacts. We conducted a complex material characterization of the perovskite active layer and device physics analysis of the perovskite solar cells before and after irradiation. Significant variations in radiation tolerance were identified between n-i-p and p-i-n architectures, highlighting the critical role of interfaces and charge-transport layers in determining device stability. The comparison between monofacial and bifacial designs further reveals the influence of rear-contact engineering on radiation-induced performance losses and degradation pathways. The results provide new insight into the relationship between device design and radiation hardness in perovskite photovoltaics and establish guidelines for the development of radiation-tolerant monofacial and bifacial PSCs for future space-energy applications.

Quantum dots (QDs) are a subject of great interest in the domains of materials science, spectroscopy, sensors, biological imaging, diagnostics, and photovoltaics. SnO₂ QDs have garnered significant attention as Electron Transport Layer (ETLs) in Perovskite Photovoltaics due to their exceptional optoelectronic properties, such as a wide bandgap, good electron mobility, high thermal stability, and compatibility with solution processing techniques. Despite the advancements in replacing conventional SnO₂ with SnO₂ QDs, current synthesis strategies are complex and rely on hazardous facilitators such as thiourea, raising concerns regarding environmental impact alongside long-term device stability. To address these issues, we report a room-temperature, ink-based approach for synthesizing ultra-small SnO₂ QDs under ambient conditions, employing environmentally benign ligands. We explore the influence of ligand methylation on the properties and performance of the SnO₂ QD inks and thin films, and analyze the chemical, morphological, crystallographic, electronic, and optoelectronic characteristics of SnO₂ QD thin films to optimize precursor formulation for depositing phase-pure SnO₂ QDs. Our optimized urea-based SnO₂ QDs deliver device PCEs of over 20%, outperforming conventional thiourea-derived SnO₂ QDs. Furthermore, our devices retained ~90% of their initial efficiency after 90 days in a dry box and over 93% under 72 hours of continuous ambient illumination, compared to ~83% and 90% retention, respectively, for thiourea-based reference devices. This novel approach may offer a pathway to stable, highly efficient, and flexible photovoltaic cells via low-temperature processing.

In 2025, approximately 18% of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) publications addressed perovskite (PVK) solar cells—nearly a threefold increase since 2020—highlighting the technique’s rapidly growing relevance.[1] Owing to its high chemical specificity and ability to probe buried interfaces without invasive sample preparation[2], ToF-SIMS is increasingly used to investigate ion migration, interfacial modification, additive passivation and degradation pathways that can be linked to changes in corresponding devices’ parameters. However, we show that ToF-SIMS data acquired from multilayered PVK solar cells cannot be interpreted analogously to its thin films.[3,4] Here, we establish a rigorously validated ToF-SIMS methodology that disentangles true ion migration from artifact-induced signals, revealing widely underappreciated measurement artifacts. Through systematic comparison of thin films and full devices based on archetypal MAPbI3 (1.6 eV) and compositionally complex (FA75Cs25)(Pb60Sn40)I3 (1.25 eV), we demonstrate that spurious ion gradients arise exclusively in multilayer stacks and originate from top-layer interactions. A controlled peeling protocol confirms their measurement-induced nature. We further introduce a fluence-matched acquisition protocol and a statistically grounded replicate-based workflow, revealing that single-profile measurements can yield contradictory interpretations, particularly for subtle interfacial phenomena (i.e. trace passivation). Applying this framework, we enable reliable analysis of pristine and aged buried self-assembled monolayers (SAMs), whose ultrathin (~1 nm) localized nature presents unique analytical challenges and growing importance in the design of molecular transport layers for high-efficiency, stable devices. Together, these results establish an artifact-aware, reproducible framework for high-fidelity ToF-SIMS depth profiling in PVK solar cells, providing a reference standard for reliable chemical analysis of complex multilayer semiconductors and their devices. As such, this work advances best practices in nanoscale characterization and in doing so supports precision interface engineering across next-generation energy technologies and beyond.

In recent years, flexible magnetoelectric (ME) composites have emerged as promising candidates for energy harvesting and self-powered sensing applications [1]. In this work, we report the fabrication of an eco-friendly flexible magnetoelectric nanogenerator based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and magnetostrictive cobalt ferrite (CoFe₂O₄, CFO) composite for energy harvesting and sensing applications. The flexible ME composite was fabricated using the solution-casting method by dispersing 10 wt% CFO nanopowder into the PVDF-HFP matrix. Structural and surface morphology analyses confirm the single-phase nature and uniform dispersion of CFO particles within the polymer matrix. The synthesized flexible ME composite exhibits a strong piezoelectric response, with a β-phase content of approximately 62% upon the addition of 10 wt% CFO, which is essential for energy harvesting applications. The polarization (P–E) and magnetization (M–H) hysteresis loops demonstrate the multiferroic behavior of the flexible PVDF-HFP/CFO composite.

The energy storage and energy harvesting capabilities of the fabricated ME nanogenerator were evaluated, and a maximum output voltage of approximately 20 V was obtained under finger tapping. The magnetoelectric coupling was indirectly confirmed by measuring the output voltage under an external DC magnetic field up to 2 kG. When subjected to an external magnetic field, magnetostrictive strain is generated in the CFO phase and transferred to the piezoelectric polymer matrix, inducing an output voltage via the direct piezoelectric effect [2]. The observed voltage generation under a magnetic field confirms the presence of ME coupling in the flexible composite.

Therefore, the eco-friendly PVDF-HFP/CFO-based flexible ME composite shows strong potential for energy storage, mechanical energy harvesting and self-powered magnetic field sensing applications.

Transparent conductive oxide (TCO) substrates are essential components in emerging photovoltaic technologies, yet they are still most commonly used as uniform, single-sided electrodes [1]. This conventional role limits their functionality in architectures that require bifacial illumination, semitransparency, tandem integration, compact monolithic assembly, or application-specific device layouts. Here, we present a substrate-engineering strategy for the fabrication of tailor-made transparent conductive glass platforms, using fluorine-doped tin oxide (FTO) as an initial model TCO.

The developed approach enables double-sided FTO deposition on glass, including electrical continuity between the conductive layers located on opposite faces of the same substrate. In parallel, controlled masking allows selective TCO deposition, defining conductive and non-conductive regions from the micrometer to millimeter scale. Together, these capabilities allow the substrate to function not only as a transparent electrode, but also as an integrated manufacturing platform where optical access, current collection, electrical interconnection, and device layout can be co-designed. In this concept, the transparent conductive substrate becomes the central architectural element of the device rather than a passive support.

This strategy is particularly relevant for monolithic photovoltaic assembly. Instead of constructing devices from separately contacted components or relying on external wiring, the transparent conductive substrate itself can provide internal electrical continuity between functional regions and opposite interfaces. Monolithic dye-sensitized solar cell (DSSC) structures have previously been explored as a route to simplify fabrication compared with conventional sandwich-type configurations [2,3]. The present work extends this principle by proposing the conductive glass substrate itself as the integration layer for compact, stacked, and tandem-relevant photovoltaic architectures.

DSSCs were selected as a first experimental benchmark because they provide a transparent, interface-sensitive platform in which optical access, electrode geometry, and bifacial operation can be directly evaluated [2,4]. As a proof‑of‑concept, two DSSCs employing complementary sensitizers were assembled in a stacked three-glass configuration. Conventional one-sided FTO substrates were used as the external electrodes, while an electrically connected double-sided FTO substrate served as the central shared conductive element. Two electrical configurations were investigated. In the parallel arrangement, both working electrodes shared the central double-sided substrate, enabling the two light-harvesting units to be coupled through a common transparent conductive platform. In the series arrangement, the counter electrode of the first cell and the working electrode of the second cell were integrated through the same central double-sided conductive substrate, demonstrating internal electrical connection between opposite cell interfaces.

These configurations highlight how complementary light-harvesting units can be combined through a shared transparent conductive substrate while maintaining optical access through the stack [5]. The approach is especially relevant for bifacial DSSCs, where device performance depends on illumination from both front and rear directions, and where electrode transparency, geometry, and interconnection strongly affect operation [4,5]. More broadly, the same substrate concept is intended to be adaptable to other TCO materials and glass-based platforms, with potential relevance for semitransparent, bifacial, tandem, and application-specific emerging photovoltaic devices.

Overall, this work introduces double-sided and selectively patterned transparent conductive substrates as a route toward true monolithic solar-cell assembly. By integrating optical access, current collection, and internal electrical interconnection into a single glass platform, conductive substrates can be transformed from passive electrodes into active manufacturing and integration layers for next-generation photovoltaic architectures.

Agriphotovoltaics (AgriPV) is defined as collocating in the same land agriculture and photovoltaic energy production, which can bring mutual benefits into food-energy-water balance in the context of changing climate [1]. Necessity to share the land and the light implies specific installation design which can differ from other applications. The presence of specific environmental solicitations resulting from the AgriPV induced microclimate and chemical conditions (application of fertilizers, fungicides, etc.), which could be very corrosive [2]. The corrosivity can strongly affect materials and the overall system efficiency, for instance energy production decreases up to 5% per year in coastal areas compared to 1% inland which is attributed to the effect of increased humidity and chloride content. The effect of specific agricultural environments on the materials used in AgriPV is however less documented. The present work reviews specific design requirements and main classes of chemicals relevant for AgriPV applications in function of the land use (selected crops) and considers the effect of selected chemicals on the stability of selected photovoltaic materials used in different technologies. Examples of the effect of some common agricultural chemicals from conventional and organic farming (nitrogen fertilizer (NH₄)₂SO₄ and copper-based fungicide CuSO₄). on the degradation mechanisms and performance of both silicon (TOPCON) and thin film (CIGS) technologies are given.

The development of flexible photovoltaic technologies has attracted significant attention due to their potential applications in wearable electronics, portable devices, and building-integrated energy systems. Among third-generation solar technologies, dye-sensitized solar cells (DSSCs) are particularly promising because of their low fabrication cost, ease of processing, and satisfactory performance under various illumination conditions. However, conventional DSSCs generally rely on rigid fluorine-doped tin oxide (FTO) glass substrates and high-temperature sintering processes (450 to 500 °C), limiting their flexibility and compatibility with roll-to-roll manufacturing. The use of polymeric substrates offers an attractive alternative, but their low thermal stability requires the development of new low-temperature photoanode fabrication strategies. In this work, a novel low-temperature approach was proposed to fabricate flexible PET/TiO₂ composite nanofibrous photoanodes for DSSC applications.

The main objective of this study was to investigate the influence of TiO₂ nanoparticle distribution within electrospun polyethylene terephthalate (PET) nanofibers on the photovoltaic performance of flexible DSSCs. To achieve this objective, highly porous PET/TiO₂ nanocomposite mats were fabricated using three different techniques: uniaxial electrospinning (UE), coaxial electrospinning (CE), and electrospinning coupled with electrospraying (E-ES). These methods enabled precise control over the localization of TiO₂ nanobars either within the fiber bulk, in the shell layer, or directly on the nanofiber surface. The originality of this work lies in the use of surfactant-capped one-dimensional TiO₂ nanobars and in the development of flexible photoanodes in which TiO₂ nanoparticles are strategically positioned at the fiber surface without requiring any post-sintering treatment. To the best of our knowledge, this is the first report describing the use of electrospun PET/TiO₂ nanofibrous structures incorporating TiO₂ nanobars as flexible photoanodes in DSSCs.

Morphological characterization by scanning electron microscopy revealed that both UE and CE methods produced homogeneous porous nanofibrous structures, whereas the E-ES process generated PET fibers decorated with TiO₂ aggregates distributed on the fiber surface and within the porous network. This architecture significantly increased surface roughness and the availability of TiO₂ active sites. Dye adsorption experiments using N719 dye demonstrated that the E-ES photoanodes exhibited superior dye-loading capacity, with increases of 110% and 337% compared with CE and UE photoanodes, respectively. The enhanced dye adsorption was attributed to the greater exposure of TiO₂ nanoparticles on the nanofiber surface, facilitating stronger interactions between the semiconductor and dye molecules.

Photovoltaic characterization showed that the position of TiO₂ nanoparticles strongly influences DSSC performance. The DSSCs fabricated with E-ES photoanodes achieved the highest short-circuit current density (0.12 mA cm⁻²), representing a 200% increase compared with the CE-based devices. Electrochemical impedance spectroscopy further confirmed that E-ES photoanodes exhibited lower charge-transfer resistance and reduced electron recombination, thereby enhancing charge collection efficiency.

Overall, this study demonstrates that controlling the spatial distribution of TiO₂ nanoparticles within electrospun PET nanofibers is crucial for improving the performance of flexible DSSCs. The electrospinning-electrospraying (E-ES) strategy provides a simple, low-cost, and scalable route for manufacturing flexible polymer-based photoanodes and represents a promising platform for future lightweight photovoltaic devices.