Farshad Jafarzadeh

Perovskite photovoltaics offer a promising route to low‐cost, low‐carbon solar energy, but progress toward largescale deployment is limited by manufacturing scalability, stability, and dependence on scarce materials. We demonstrate fully roll‐to‐roll coated, large‐area back‐contact perovskite photovoltaic modules based on a microgroove architecture that removes the need for transparent conductors such as Indium Tin Oxide (ITO). Devices are continuously manufactured on flexible substrates using scalable embossing, vacuum deposition, solution printing, and encapsulation. Modules with active areas up to 48.2 cm ² achieve record power conversion efficiencies exceeding 12.5 % and are further scaled to panels larger than 1000 cm ² . The first comprehensive stability study of fully roll‐to‐roll coated perovskite modules is presented, including ISOS‐compliant accelerated ageing and up to five months of outdoor operation. Nanoscale x‐ray fluorescence tomography identifies key degradation pathways within the microgroove architecture. In addition to scalable fabrication, the architecture enables intrinsic bifaciality, improved angular response, and linear shading tolerance, enhancing real‐world energy yield and supporting sustainable largescale deployment beyond conventional photovoltaics.

Perovskite solar cells (PSCs) have recently demonstrated laboratory‐scale power conversion efficiencies (PCEs) exceeding 27%, a value that now matches the most efficient silicon photovoltaics. Their low‐temperature, solution‐processable fabrication and compatibility with flexible substrates position PSCs as candidates for next‐generation photovoltaic technologies. Notably, PSCs fabricated on flexible substrates have been shown to demonstrate efficiencies that exceed 26% PCE, however the efficiency of flexible modules remains under 22%. Roll‐to‐roll (R2R) deposition has emerged as a leading candidate to transition PSC fabrication to a practical manufacturing environment. In this review, we focus on R2R processing of PSCs and discuss the techniques that have been developed to control perovskite structure, crystallinity, and morphology. In particular, we explore the effects of perovskite composition, solvent engineering, film‐drying, and additive engineering, which can be harnessed to optimise device performance, with fully R2R‐fabricated PSCs demonstrated having PCEs above 15%, and R2R printed modules reaching a PCE of 11%. A number of challenges remain, including maintaining film quality at high substrate throughput, ensuring the long‐term stability of devices, and reducing the cost of module integration.

The demand for flexible and wearable sensors is more and more increasing in a wide range of applications. Specifically, in the field of medical diagnostics and radiation therapy, a flexible X-ray dosimeter is extremely desirable, due to the possibility of a conformal contact between the human body and the sensing device. Here we report on a flexible X-ray detector based on an ultrathin (500 nm) film of a wide-bandgap metal-halide-perovskite (FAPbBr3) as absorbing layer, showing sensitivity values up to 375.24 μC Gy-1 cm-2 to X-rays with energy up to 40 keV, excellent linearity with the radiation dose-rate (linearity coefficient 0.97), and very good operational stability under 12 h of continuous irradiation. The device, relying on a simple low-cost technology, exploits the built-in potential of a typical p-in architecture used in perovskite solar cells, hence it does not require a bias voltage to operate, allowing for continuous radiation monitoring with no risk of battery depletion.

The growing demand for sustainable energy solutions has made the development of scalable, efficient, and cost‐effective perovskite solar cells (PSCs) increasingly important. Wide‐bandgap perovskites (WB‐PSCs) stand out due to their efficiency in low‐light conditions and their use in tandem solar cells. WB‐PSCs are currently behind conventional PSCs in upscaling, with limited success in printing wide bandgap PSCs. Developing upscaling methods is essential to fully realize their potential in the renewable energy sector. This research addresses the development of roll‐to‐roll (R2R) slot‐die coating of Cs_0.05FA_0.95PbBr₃‐based WB‐PSCs by focusing on improving the film formation process and ink formulation. By adding optimal concentration of CsBr and performing in situ characterization, we obtained Cs_0.05FA_0.95PbBr₃ films with enhanced morphology and crystallinity in ambient conditions (50% RH), without inducing secondary phase formation. In addition, slot‐die coating defects are eliminated through introducing DMSO: Butanol (9:1) solvent system. The R2R coated wide‐bandgap PSCs reaches a power conversion efficiency (PCE) of up to 8.97% under 1‐sun conditions and 18.3% PCE under indoor conditions. The corresponding R2R coated modules with a 5 × 5 cm² active area achieve a PCE of 5.8%, representing a crucial step towards the high‐throughput, cost‐effective production of perovskite solar modules.

Transparent photovoltaics for building integration represent a promising approach for renewable energy deployment. These devices require transparent electrodes to manage transmittance and to ensure proper cell operation. In this study, transparent FAPbBr(3)-based perovskite solar cells optimized via a passivation treatment were demonstrated with average visible transmittance values above 60% and light utilization efficiencies up to 5.0%. Experiments under varying ultraviolet (UV) irradiance intensities from both front and rear directions revealed performance differences correlated with diffusion-limited transport and open-circuit voltage changes. Combining the UV-radiated experiments and drift-diffusion simulations, an asymmetry between the diffusion lengths of electrons and holes in the perovskite is revealed, with estimated values resulting in less than 50 nm and more than 99 nm, respectively. Our methods not only identify electron-hole diffusion length differences but also introduce a general protocol for characterizing solar cells with transparent electrodes.

Perovskite solar cells have rapidly advanced, achieving over 26% power conversion efficiency on the laboratory scale. However, transitioning to large-scale production remains a challenge due to limitations in conventional fabrication methods like spin coating. Here, we introduce an optimized blade coating process for the scalable fabrication of large-area (15 cm × 15 cm) perovskite solar modules with a nickel oxide hole transport layer, performed in ambient air and utilizing a non-toxic solvent system. Self-assembled monolayers between the nickel oxide and perovskite layer improve the uniformity and morphology of the perovskite film. Perovskite solar modules with a 110 cm² active area achieve a power conversion efficiency of 12.6%. Moreover, encapsulated modules retained 84% of their initial efficiency after 1,000 hours at 85 °C in air (ISOS-T-1). This study demonstrates progress in the large-scale production of perovskite solar cells that combine efficiency with long-term stability.

Efficient semi‐transparent solar cells can extend the adoption of photovoltaics beyond standard utility‐scale, commercial, or residential applications. Halide perovskites are particularly suitable in this respect owing to their tunable bandgap. The main drawbacks in the development of transparent perovskite solar cells are the high open‐circuit voltage (V_oc) deficit and the difficulties in depositing high‐quality thin films over large area substrates, given the low solubility of bromide and chloride precursors. In this work, passivation strategies are developed for the high bandgap Br perovskite able to reduce charge recombination and consequently improve the V_oc. The study demonstrates 1 cm² perovskite solar cells with V_oc up to 1.73 V (1.83 eV Quasi Fermi Level Splitting) and a PCE of 8.1%. The average visible transmittance (AVT) exceeds 70% by means of a bifacial light management and a record light utilization efficiency (LUE) of 5.72 is achieved. Moreover, the potential use of the technology is evaluated toward Internet of Things (IoT) application owing to a bifaciality factor of 87% along with 17% PCE under indoor lighting. Finally, the up‐scaling is demonstrated by fabricating 20 cm² active area modules with PCE of 7.3% and V_oc per cell up to 1.65 V.

Perovskite solar cells (PSCs) offer impressive performance and flexibility, thanks to their simple, low-temperature deposition methods. Their band gap tunability allows for a wide range of applications, transitioning from opaque to transparent devices. This study introduces the first flexible, bifacial PSCs using the FAPbBr₃ perovskite. We investigated the impact of optimizing electron and hole transport layers on the cells' bifaciality, transparency, and stability. PSCs achieved a maximum power conversion efficiency (PCE) of 6.8 and 18.7% under 1 sun and indoor light conditions (1200 lx), respectively, showing up to 98% bifaciality factor and an average visible transmittance (AVT) of 55%. Additionally, a P1-P2-P3 laser ablation scheme has been developed on the flexible poly(ethylene terephthalate) (PET) substrate for perovskite solar modules showing a PCE of 4.8% and high geometrical fill factor (97.8%). These findings highlight the potential of flexible, bifacial PSCs for diverse applications such as building-integrated photovoltaics (BIPV), agrivoltaics, automotive technology, wearable sensors, and Internet of things (IoT).

Flexible perovskite solar cells are lightweight, bendable, and applicable to curved surfaces. Polyethylene terephthalate (PET) has become the substrate of choice compared to other plastic substrates like polyethylene naphthalate. PET is not only stable but also much cheaper to manufacture, an important factor for photovoltaics (PV). Herein, highly efficient devices on PET are demonstrated using a dual low‐temperature (≤100 °C) approach, first by anion mixing (replacing I with Br) of the lead‐containing perovskite composition, increasing bandgap (42% improvement), and then by interfacial engineering with tetrabutylammonium bromide (TBAB) (a further 26% improvement), reaching efficiencies of 28.9% at 200 lx and a record 32.5% at 1000 lx. The TBA⁺cation intercalates into the structure, substituting formamidinium cations at the perovskite/TBAB interface, inducing the formation of large‐sized, lower dimensional structures over the 3D perovskite matrix. The resulting PV cell has 1.4 times higher carrier lifetime, one order of magnitude lower leakage currents, and 3 times lower defect densities, suppressing recombination. Importantly, stability (ISOS‐D1 protocol) improves by more than double with treatment. Highly efficient and stable cells on PET films enable seamless integration with wearable, portable, smart building, and Internet of Things electronic devices, expanding the reach of indoor applications.