optoelectronic devices, a novel lowcost and highly efficient photovoltaic (PV) material emerged. Only 10 years after the first reported perovskite solar cells (PSCs), power conversion efficiencies (PCEs) above 23% were certified, exceeding those of much longer established thin-film PV technologies, including organic photovoltaics (OPV) and inorganic thin-film PV based on copper indium gallium selenide (CIGS) or cadmium telluride (CdTe). [1] The material class of hybrid organic-inorganic perovskites combines excellent optoelectronic properties, such as long diffusion lengths [2] and short absorption lengths, [3] with the ease of solution processing, low energy payback times, and low-cost precursor materials. [4] Moreover, the optoelectronic properties and the material stability can be engineered by varying the constituents in the perovskite crystal structure ABX 3 . For example, the bandgap (E G ) can be tuned by changing the stoichiometric ratio of Br and I at the halogen anion site X. [5][6][7] In order to improve the stability of hybrid organic-inorganic perovskites, compositional engineering of the cation site A was demonstrated to be successful via combining methylammonium (CH 3 NH 3 + or MA + ), formamidinium (CH 5 N 2 + or FA + ), Cs + , and Rb + ions in the so-called multi-cation perovskites. [8][9][10][11] Three key challenges hinder today the economical breakthrough of PSCs:Stability: First, the instability of PSCs against moisture, oxygen, light, and temperature limits the lifetime of PSCs to a fraction of the warranty lifetime (often >25 years) of the market dominating crystalline silicon (c-Si) PV. [12] Very respectable progress has been made over recent years to enhance the stability of PSCs by demonstrating stability over 1000 h, but significant further advances in terms of stability are needed to lift the technology to a level where it is ready to compete with, or be a bolt-on tandem companion to the current PV heavyweight of c-Si. A number of reviews cover recent developments on the topic of stability. [13][14][15][16][17] Toxicity: Second, highly efficient PSCs still contain lead, the toxicity of which hampers the acceptance of the technology and could conflict with legislative barriers. [18] Other recent reviews present progress with respect to this challenge. [19,20] Upscaling: Third, the upscaling of perovskite PV devices to commercial PV module sizes (>1 m 2 ) must be achieved. To date, the vast majority of research and development of PSCs is still Hybrid organic-inorganic metal halide perovskite semiconductors provide opportunities and challenges for the fabrication of low-cost thin-film photovoltaic devices. The opportunities are clear: the power conversion efficiency (PCE) of small-area perovskite photovoltaics has surpassed many established thin-film technologies. However, the large-scale solution-based deposition of perovskite layers introduces challenges. To form perovskite layers, precursor solutions are coated or printed and these must then be crystallized into the perovskite structur...

A key challenge for the commercialization of perovskite photovoltaics is the transfer of high‐quality spin coated perovskite thin‐films toward applying industry‐scale thin‐film deposition techniques, such as slot‐die coating, spray coating, screen printing, or inkjet printing. Due to the complexity of the formation of polycrystalline perovskite thin‐films from the precursor solution, efficient strategies for process transfer require advancing the understanding of the involved dynamic processes. This work investigates the fundamental interrelation between the drying dynamics of the precursor solution thin‐film and the quality of the blade coated polycrystalline perovskite thin‐films. Precisely defined drying conditions are established using a temperature‐stabilized drying channel purged with a laminar flow of dry air. The dedicated channel is equipped with laser reflectometry at multiple probing positions, allowing for in situ monitoring of the perovskite solution thin‐film thickness during the drying process. Based on the drying dynamics as measured at varying drying parameters, namely at varying temperature and laminar air flow velocity, a quantitative model on the drying of perovskite thin‐films is derived. This model enables process transfer to industry‐scale deposition systems beyond brute force optimization. Via this approach, homogeneous and pinhole‐free blade coated perovskite thin‐films are fabricated, demonstrating high power conversion efficiencies of up to 19.5% (17.3% stabilized) in perovskite solar cells.

Hybrid perovskite photovoltaics combine high performance with the ease of solution processing. However, to date, a poor understanding of morphology formation in coated perovskite precursor thin films casts doubt on the feasibility of scaling-up laboratory-scale solution processes. Oblique slot jet drying is a widely used scalable method to induce fast crystallization in perovskite thin films, but deep knowledge and explicit guidance on how to control this dynamic method are missing. In response, we present a quantitative model of the drying dynamics under oblique slot jets. Using this model, we identify a simple criterion for successful scaling of perovskite solution printing and predict coating windows in terms of air velocity and web speed for reproducible fabrication of perovskite solar cells of ∼15% in power conversion efficiencyin direct correlation with the morphology of fabricated thin films. These findings are a corner stone toward scaling perovskite fabrication from simple principles instead of trial and error optimization.

Given the outstanding progress in research over the past decade, perovskite photovoltaics (PV) is about to step up from laboratory prototypes to commercial products.For this to happen, realizing scalable processes to allow the technology to transition from solar cells to modules is pivotal. This work presents all-evaporated perovskite PV modules with all thin films coated by established vacuum deposition processes. A common 532-nm nanosecond laser source is employed to realize all three interconnection lines of the solar modules. The resulting module interconnections exhibit low series resistance and a small total lateral extension down to 160 μm. In comparison with interconnection fabrication approaches utilizing multiple scribing tools, the process complexity is reduced while the obtained geometrical fill factor of 96% is comparable with established inorganic thin-film PV technologies. The all-evaporated perovskite minimodules demonstrate power conversion efficiencies of 18.0% and 16.6% on aperture areas of 4 and 51 cm 2 , respectively. Most importantly, the allevaporated minimodules exhibit only minimal upscaling losses as low as 3.1% rel per decade of upscaled area, at the same time being the most efficient perovskite PV minimodules based on an all-evaporated layer stack sequence.

In this work, we examine the effect of microstructure on ion-migrationinduced photoluminescence (PL) quenching in methylammonium lead iodide perovskite films. Thin films were fabricated by two methods: spin-coating, which results in randomly oriented perovskite grains, and zone-casting, which results in aligned grains. As an external bias is applied to these films, migration of ions causes a quenching of the PL signal in the vicinity of the anode. The evolution of this PLquenched zone is less uniform in the spin-coated devices than in the zone-cast ones, suggesting that the relative orientation of the crystal grains plays a significant role in the migration of ions within polycrystalline perovskite. We simulate this effect via a simple Ising model of ionic motion across grains in the perovskite thin film. The results of this simulation align closely with the observed experimental results, further solidifying the correlation between crystal grain orientation and the rate of ionic transport.

The unprecedentedly fast rise in power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) over the last decade [1] now surpassing 25%-triggered enormous scientific and industrial interest in solution-processed, large-area perovskite photovoltaics. [2] However, PCEs of PSCs and perovskite modules processed with scalable coating techniques lag behind solution-processed small-area PSCs. [3] The record certified PCE of a large, solution-processed perovskite module (802 cm 2 ) of 17.9% was achieved by Panasonic. [4] Some of the losses on upscaling to modules originate from the monolithic interconnection schemes, including the sheet resistances of the transparent conductive oxides (TCOs), the series resistances of the TCO-Electrode interconnections, and the inactive areas due to the scribing lines. [5] A decrease in PCE of around 1.5% abs is typical for laser patterning of the three scribe lines (p1, p2, p3), nearly independent on the module's aperture area. [6] However, just as in other researched thin-film photovoltaic (PV) technologies, [7] the dominant losses of PCE on large-area perovskite modules are caused by morphological defects in the absorber layer such as microcracks, material impurities, or, most commonly, shunt paths. Even one defect in the perovskite thin film can shunt a whole subcell or decrease its performance substantially by introducing nonradiative recombination. [6] These upscaling losses statistically increase with the modules' aperture area because the probability of defects scales with the area, limiting the achievable PCE of the whole module. [8] The challenge of depositing homogeneous high-quality perovskite thin films on large areas arises from the complexity of the involved kinetic and thermodynamic processes. [9] In this work, we will focus on scalable perovskite processing from solution (although thermal coevaporation of the precursor materials [10] is a very promising fabrication route, as well). The reason for this focus is simply that the experimental techniques presented here are not yet adapted to operation in vacuum.The formation of perovskite thin films from solution is commonly described via the following four stages: [3] I) coatingdeposition of a wet film of precursor solution; II) drying-

Controlling the thickness and homogeneity of thin passivation layers on polycrystalline perovskite thin films is challenging. We report CVD polymerization of poly(p-xylylene) layers at controlled substrate temperatures for efficient surface passivation of perovskite films.

In this work, we introduce a bilayer ETL composed of lithium (Li)-doped compact SnO2 (c-SnO2) and potassium-capped SnO2 nanoparticle layers (NP-SnO2) to enhance the electron extraction and charge transport properties in perovskite solar cells, resulting in an improved PCE and a strongly reduced J–V hysteresis.