high defect tolerance, long carrier diffusion length, and compatibility toward scalable manufacturing processes to name a few. [2][3][4][5][6][7] However, hybrid perovskites face severe degradation issues under operative conditions, which stem from the (photo) chemical instability when exposed to moisture, oxygen, UV light, and heat. [8][9][10][11][12] Among other reasons, the presence of the hydrophobic organic cation, e.g., methylammonium, can accelerate the degradation path. [12][13][14] For this reason, a greater focus has been devoted to exploring inorganic elements to replace the organic cations, for instance, using cesium to form CsPbX 3 all-inorganic perovskites. This system has been revealed of particular interest especially for the improved thermal stability of the material and, consequently, the enhanced device lifetime. [13] CsPbI 3 and CsPbBr 3 are the most studied materials within this class, with a rapid boost of their use for highly efficient solar cells, reaching 19.03% in 2019. [15] However, the PCE of CsPbX 3 -based devices are still lower than their organic-inorganic counterparts and far from the Shockley-Queisser limit calculated for their bandgap. [16] Therefore, major efforts are required to stabilize the CsPbI 3 structure and to fabricate high quality CsPbX 3 thin films, before upscaling the manufacturing toward marketable devices. In this work, we provide a compelling perspective on the most recent and innovative strategies to tackle this challenge. The structural and optoelectronic properties of CsPbX 3 materials are first sorted out, with a focus on the film morphology, crystal structure, and phase transitions of each system. Second, methods for improving the photovoltaic performances and the stability of CsPbX 3 -based devices are reported, focusing on the highest PCE and the longest device lifetimes reported up to date. Finally, we provide a perspective on the state of the art and future challenges for the upscaling of all-inorganic perovskite modules.

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The industrialization of perovskite solar cells relies on solving intrinsic‐to‐material issues. To reach record efficiencies perovskite deposition needs to be finely adjusted by multi‐step processes, in a humidity free glove‐box environment and by means of hardly scalable techniques often associated with toxic solvents and anti‐solvent dripping/bath. Herein, the use of polymeric material is proposed to deposit perovskite layers with easy processability. To the scope, a starch‐polymer/perovskite composite is developed to suit slot‐die coating technique requirement, allowing the deposition of hybrid halide perovskite material in a single straightforward step without the use of toxic solvents, and in uncontrolled humid environment (RH up to 70 %). The starch‐polymer increases the viscosity of the perovskite precursor solutions and delays the perovskite crystallization that results in the formation of perovskite films at mild temperature (60 °C) with good morphology. These innovative inks enables the fabrication of flexible solar cells with p‐i‐n configuration featured by a power conversion efficiency higher than 3 %. . Overall, this approach can be exploited in the future to massively reduce perovskite manufacturing costs related to keeping the entire fabrication line at high‐temperature and under nitrogen or dry conditions.

We synthetized a new rod-coil block copolymer (BCP) based on the semiconducting polymerpoly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) and poly-4-vinylpyridine (P4VP), tailored to produce water-processable nanoparticles (WPNPs) in blend with phenyl-C71-butyric acid methyl ester (PC71BM). The copolymer PTB7-b-P4VP was completely characterized by means of two-dimensional nuclear magnetic resonance (2D-NMR), matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS), size-exclusion chromatography (SEC), and differential scanning calorimetry (DSC) to confirm the molecular structure. The WPNPs were prepared through an adapted miniemulsion approach without any surfactants. Transmission electron microscopy (TEM) images reveal the nano-segregation of two active materials inside the WPNPs. The nanostructures appear spherical with a Janus-like inner morphology. PTB7 segregated to one side of the nanoparticle, while PC71BM segregated to the other side. This morphology was consistent with the value of the surface energy obtained for the two active materials PTB7-b-P4VP and PC71BM. The WPNPs obtained were deposited as an active layer of organic solar cells (OSCs). The films obtained were characterized by UV-Visible Spectroscopy (UV-vis), atomic force microscopy (AFM), and grazing incidence X-ray diffraction (GIXRD). J-V characteristics of the WPNP-based devices were measured by obtaining a power conversion efficiency of 0.85%. Noticeably, the efficiency of the WPNP-based devices was higher than that achieved for the devices fabricated with the PTB7-based BCP dissolved in chlorinated organic solvent.

All‐inorganic perovskites are a promising solution for the fabrication of thermally stable perovskite solar cells (PSCs) with remarkable performances. However, a high annealing temperature is required for the stabilization of the photoactive phase of CsPbI3, which represents a limiting factor for their potential scaling‐up and manufacturing at industrial scale. This work demonstrates a new process for the stabilization of CsPbI3‐xBrx perovskite at lower annealing temperature of 180°, based on a rational halogen substitution enabled by the introduction of dimethylammonium (DMA) additives. Bromide inclusion favors indeed the conversion from the intermediate phases to CsPbI3‐xBrx. Standard mesoscopic solar cells prepared with this approach achieve a power conversion efficiency (PCE) of 14.86%, with reduced voltage losses and increased fill factor (FF) compared to the reference device. Moreover, this work proves that a rational substitution of the halide in the DMA salt is also beneficial for the devices annealed at higher temperature, achieving an encouraging PCE of 16.23%. By reducing the processing temperature, this new method widens the range of applications of all‐inorganic PSCs toward temperature‐sensitive materials and industrial applications.This article is protected by copyright. All rights reserved.