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Semitransparent perovskite solar cells (ST‐PSCs) hold great promise for various commercial applications, including building integrated photovoltaics and tandem solar cells. The all‐inorganic perovskite, known for its outstanding optical transparency and thermal stability, emerges as a top contender for ST‐PSCs. However, challenges persist due to phase segregation, which hampers charge carrier transport and operational stability. In this study, an approach is proposed to address these challenges by employing strain engineering to reconstruct the perovskite texture, eliminating inhomogeneities within the perovskite film. The crucial role of compressive strain in stabilizing lattice rigidity and suppressing light‐induced ion migration is demonstrated. Furthermore, a transparent light‐harvesting architecture is devised utilizing a sandwiched layer of gold embedded between MoO3. This design enhances power generation by efficiently harnessing incident light from both the front and rear panel surfaces. Therefore, bifacial ST‐PSCs achieve an equivalent efficiency (ηeq) of 13.97% with an average visible light transmittance of 41.58%, yielding an outstanding light utilization efficiency of up to 5.8%. This research not only advances the understanding of perovskite material phase‐segregation behavior but also introduces an effective strategy for enhancing optical gain without compromising the semitransparent characteristics. [ABSTRACT FROM AUTHOR]

Highlights: Low-temperature fabrication of black-phase CsPbI3 perovskite films is first demonstrated by using diphenylphosphinic chloride additive under 30–50 °C, arising from the steric effect and chloride insertion engineering. Large-area high-quality all-inorganic perovskite films with fewer defects enhanced crystallographic orientation, and excellent environmental stability is fabricated. The record performances are demonstrated for flexible wearable photodetectors with a responsivity of 42.1 A W−1, a detectivity of 1.3 × 1014 Jones, high-fidelity image, photoplethysmography sensor functions, and high mechanical stability. Flexible wearable optoelectronic devices fabricated from organic–inorganic hybrid perovskites significantly accelerate the development of portable energy, biomedicine, and sensing fields, but their poor thermal stability hinders further applications. Conversely, all-inorganic perovskites possess excellent thermal stability, but black-phase all-inorganic perovskite film usually requires high-temperature annealing steps, which increases energy consumption and is not conducive to the fabrication of flexible wearable devices. In this work, an unprecedented low-temperature fabrication of stable black-phase CsPbI3 perovskite films is demonstrated by the in situ hydrolysis reaction of diphenylphosphinic chloride additive. The released diphenyl phosphate and chloride ions during the hydrolysis reaction significantly lower the phase transition temperature and effectively passivate the defects in the perovskite films, yielding high-performance photodetectors with a responsivity of 42.1 A W−1 and a detectivity of 1.3 × 1014 Jones. Furthermore, high-fidelity image and photoplethysmography sensors are demonstrated based on the fabricated flexible wearable photodetectors. This work provides a new perspective for the low-temperature fabrication of large-area all-inorganic perovskite flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

Formamidinium‐lead triiodide (FAPbI3) perovskite holds promise as a prime candidate in the realm of perovskite photovoltaics. However, the photo‐active α‐FAPbI3 phase, existing as a metastable state, is observable solely at elevated temperatures and is susceptible to degradation into the δ‐phase in ambient air. Therefore, the attainment of phase‐stable α‐FAPbI3 in ambient conditions has become a crucial objective in perovskite research. Here, we proposed an efficient conversion process of PbI2 into the α‐FAPbI3 perovskites in ambient air. This conversion was facilitated by the introduction of chelating molecules, which interacted with PbI2 to form an intermediate phase. Due to the reduced formation barrier resulting from the altered reaction pathway, this stable intermediate phase transitioned directly into α‐FAPbI3 upon the deposition of the organic cation solution, effectively bypassing the formation of δ‐FAPbI3. Consequently, the ambient‐fabricated FAPbI3 perovskite solar cells (PSCs) exhibited an outstanding power conversion efficiency of 25.08 %, along with a high open‐circuit voltage of 1.19 V. Furthermore, the unencapsulated devices demonstrated remarkable environmental stability. Notably, this innovative approach promises broad applicability across various chelating molecules, opening new avenues for further progress in the ambient air fabrication of FAPbI3 PSCs. [ABSTRACT FROM AUTHOR]

The improvement of photovoltaic and stability performance of tin (Sn)‐based halide perovskite solar cells is impeded by notorious oxidation issues and Anderson localization. Despite previous implements in antioxidation through the incorporation of Lewis base additives, there still exist ongoing uncertainties surrounding its complex interaction mechanisms. A perplexing phenomenon regarding accelerated oxidation in acrylic acid is discovered that deviates from conventional Lewis base–acid reaction. The underlying insights into the deprotonation of acrylic acid followed by the formation of a "tripod" ionic bonding form are provided, which results in amplifying the delocalization effect of electrons of Sn2+. Furthermore, with the assistance of acrylamide and acrolein, synergistic enhancement in terms of the antioxidation and suppression of Anderson localization can be achieved — a concept referred to as "Dual Synergistic Engineering". This suppresses the oxidation of Sn2+ and reduces Sn4+ content by ≈76%. Meanwhile, the diffusion length is prolonged significantly from 195.9 to 458.9 nm. The optimized all‐inorganic Sn/Pb‐based perovskite solar cells exhibit a power conversion efficiency of above 14% with enhanced stability. These findings provide an alternative viewpoint for comprehending the impact of chemical interaction on oxidation and crystal growth in Sn/Pb‐based perovskites. [ABSTRACT FROM AUTHOR]

In situ cyclized polyacrylonitrile (CPAN) is developed to replace n‐type metal oxide semiconductors (TiO2 or SnO2) as an electron selective layer (ESL) for highly efficient and stable n‐i‐p perovskite solar cells (PSCs). The CPAN layer is fabricated via facile in situ cyclization reaction of polyacrylonitrile (PAN) coated on a conducting glass substrate. The CPAN layer is robust and insoluble in common solvents, and possesses n‐type semiconductor properties with a high electron mobility of 4.13×10−3 cm2 V−1 s−1. With the CPAN as an ESL, the PSC affords a power conversion efficiency (PCE) of 23.12 %, which is the highest for the n‐i‐p PSCs with organic ESLs. Moreover, the device with the CPAN layer holds superior operational stability, maintaining over 90 % of their initial efficiency after 500 h continuous light soaking. These results confirm that the CPAN layer would be a desirable low‐cost and efficient ESL for n‐i‐p PSCs and other photoelectronic devices with high performance and stability. [ABSTRACT FROM AUTHOR]

As a fundamental thermodynamic parameter, pressure serves as an effective tool to control the structures and properties of functional materials. To date, numerous pressure‐engineering methods have been introduced to enhance perovskite structures and devices. This paper comprehensively reviews the advances in understanding the effects of pressure on perovskite materials and devices, encompassing both low and high‐pressure influences. These effects are categorized into six distinct groups based on their underlying mechanisms, detailing the evolution of perovskite structures from macroscopic to microscopic levels, and exploring the interplay between these structures and their functional characteristics. Finally, the current challenges and offer insights into the future prospects for harnessing pressure effects to further develop perovskite structures, properties, and devices are assessed. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have seen remarkable progress in recent years, largely attributed to various additives that enhance both efficiency and stability. Among these, fluorine-containing additives have garnered significant interest because of their unique hydrophobic properties, effective defect passivation, and regulation capability on the crystallization process. However, a targeted structural approach to design such additives is necessary to further enhance the performance of PSCs. Here, fluoroalkyl ethylene with different fluoroalkyl chain lengths (CH2CH(CF2)nCF3, n = 3, 5, and 7) as liquid additives is used to investigate influences of fluoroalkyl chain lengths on crystallization regulation and defect passivation. The findings indicate that optimizing the quantity of F groups plays a crucial role in regulating the electron cloud distribution within the additive molecules. This optimization fosters strong hydrogen bonds and coordination effects with FA+ and uncoordinated Pb2+, ultimately enhancing crystal quality and device performance. Notably, 1H,1H,2H-perfluoro-1-hexene (PF3) with the optimal number of F presents the most effective modulation effect. A PSC utilizing PF3 achieves an efficiency of 24.05%, and exhibits exceptional stability against humidity and thermal fluctuations. This work sheds light on the importance of tailored structure designs in additives for achieving high-performance PSCs. [ABSTRACT FROM AUTHOR]

Well‐engineered buried interfaces play a pivotal role in achieving high‐performance perovskite solar cells (PSCs). A superior buried interface involves controlled perovskite crystallization, efficient charge transfer across interfaces, and robust interfacial bonding. Here, a class of innovative additives, benzoyl sulfonyl molecules including 4‐sulfobenzoic acid monopotassium salt (K‐SBA), and 4‐sulfamoylbenzoic acid (SBA) is introduced to tailer the SnO2/perovskite buried interface, aiming to meet these essential criteria. Among them, K‐SBA performed better. The findings reveal that the functional groups of K‐SBA establish interactions with both SnO2 and perovskite, leading to effective bilateral passivation and mitigation of interface stress. This results in the formation of a pore‐free buried interface and high‐quality perovskite films with substantial crystal sizes. Consequently, PSCs incorporating K‐SBA exhibited a notable increase in efficiency, achieving 24.56% efficiency compared to the control device's 22.27%. Furthermore, these K‐SBA‐enhanced PSCs maintain 90% of their original efficiency even after 500 h of maximum power point tracking. This work provides valuable insights for further refinement and advancement of buried interfaces in PSCs. [ABSTRACT FROM AUTHOR]

Metal-halide perovskite solar cells have garnered significant research attention in the last decade due to their exceptional photovoltaic performance and potential for commercialization. Despite achieving remarkable power conversion efficiency of up to 26.1%, a substantial discrepancy persists when compared to the theoretical Shockley–Queisser (SQ) limit. One of the most serious challenges facing perovskite solar cells is the energy loss incurred during photovoltaic conversion, which affects the SQ limits and stability of the device. More significant than the energy loss occurring in the bulk phase of the perovskite is the energy loss occurring at the surface-interface. Here, we provide a systematic overview of the physical and chemical properties of the surface-interface. Firstly, we delve into the underlying mechanism causing the energy deficit and structural degradation at the surface-interface, aiming to enhance the understanding of carrier transport processes and structural chemical reactivity. Furthermore, we systematically summarized the primary modulating pathways, including surface reconstruction, dimensional construction, and electric-field regulation. Finally, we propose directions for future research to advance the efficiency of perovskite solar cells towards the radiative limit and their widespread commercial application. [ABSTRACT FROM AUTHOR]

Low‐dimensional (LD) perovskite has provided an exciting avenue for exploring stable perovskite solar cells (PSCs). However, PSCs based on LD perovskites still suffer from poor efficiency owing to unfavorable charge carrier dynamics. Here, cystamine (CYS) is employed as a ligand to construct LD Dion‐Jacobson (LDDJ) perovskite (CYS)MAn‐1PbnI3n+1 (n = 1, 2, 3..., MA: methylamine) for improving carrier properties. The disulfide bond not only changes the polarization characteristic but also increases the coupling between inorganic slabs due to the low barrier of rotation around the S‐S axis, thus reducing the exciton binding energy of CYS‐based LDDJ perovskite. Disulfide bonds provide a scene for charge localization in the interlayer region, which is conducive to reducing the anisotropy of charge transfer. Thanks to these merits, the (CYS)MA4Pb5I16 film delivers improved carrier diffusion length (electron for 1345 nm and hole for 950 nm) and mobility (9.23 cm2 V−1 S−1). As a result, the (CYS)(MA)4Pb5I16 PSC achieves a champion power conversion efficiency (PCE) of 16.52%, which is much higher than that of HDA and BA cations‐based PSCs (HDA: 1,6‐Hexanediamine, BA: Butylamine). Furthermore, the state‐of‐the‐art device only lost 8% of its initial PCE after 1600 h in the atmosphere. [ABSTRACT FROM AUTHOR]

2D chiral perovskite has greatly boosted the development of optoelectronic devices, ranging from nonlinear optics, spintronics, and ferroelectrics to energy harvesting devices. Despite circularly polarized light (CPL) detection based on chiral perovskite has been achieved, the environmental humidity‐, ultraviolet (UV), and temperature‐induced structural degradation and its large electro‐phonon coupling restrict its commercial application. Here, this study first realizes polymerized chiral perovskite single‐crystal films by combining in situ cross‐linking polymerization with the space‐confined crystallization method. Compared with uncross‐linked chiral perovskites, cross‐linked chiral perovskites exhibit enhanced crystallinity and lattice rigidity, yielding high‐performance circularly polarized photodetectors with a maximum anisotropy factor of 0.22, the responsivity of 1.6 A W−1, and detectivity of 2.17 × 1013 Jones. In addition, flexible circularly polarized photodetectors with extremely high mechanical stability are also realized originating from the polymer‐like behavior of cross‐linked chiral perovskite single‐crystal films. This study opens up new avenues to further enhance the performance and stability of portable and wearable devices based on chiral perovskites. [ABSTRACT FROM AUTHOR]

Despite the remarkable progress made in perovskite solar cells, great concerns regarding potential Pb contamination risk and environmental vulnerability risks associated with perovskite solar cells pose a significant obstacle to their real-world commercialization. In this study, we took inspiration from the ensnaring prey behavior of spiders and chemical components in spider web to strategically implant a multifunctional mesoporous amino-grafted-carbon net into perovskite solar cells, creating a biomimetic cage traps that could effectively mitigate Pb leakage and shield the external invasion under extreme weather conditions. The synergistic Pb capturing mechanism in terms of chemical chelation and physical adsorption is in-depth explored. Additionally, the Pb contamination assessment of end-of-life perovskite solar cells in the real-world ecosystem, including Yellow River water and soil, is proposed. The sustainable closed-loop Pb management process is also successfully established involving four critical steps: Pb precipitation, Pb adsorption, Pb desorption, and Pb recycling. Our findings provide inspiring insights for promoting green and sustainable industrialization of perovskite solar cells. Potential lead contamination risk and environmental vulnerability risk impose a significant obstacle for the commercialization of perovskite solar cells. Here, the authors create a biomimetic cage traps to mitigate lead leakage and establish a sustainable closed-loop lead management process. [ABSTRACT FROM AUTHOR]

Highlights: Multidimensional detection of intensity, wavelength, polarization, and angle of the incidence light significantly accelerates the development of optical information technology and artificial intelligence fields. The first comprehensive overview of the advancement of multifunctional photodetectors for perovskite semiconductors ranging from polarized light detection, spectral detection, and angle-sensing detection to self-powered detection is summarized. The existing problems and perspectives are discussed which can inspire more researchers to rationally design new perovskite materials and micro/nano-structure for high-performance multifunctional photodetectors. Multifunctional photodetectors boost the development of traditional optical communication technology and emerging artificial intelligence fields, such as robotics and autonomous driving. However, the current implementation of multifunctional detectors is based on the physical combination of optical lenses, gratings, and multiple photodetectors, the large size and its complex structure hinder the miniaturization, lightweight, and integration of devices. In contrast, perovskite materials have achieved remarkable progress in the field of multifunctional photodetectors due to their diverse crystal structures, simple morphology manipulation, and excellent optoelectronic properties. In this review, we first overview the crystal structures and morphology manipulation techniques of perovskite materials and then summarize the working mechanism and performance parameters of multifunctional photodetectors. Furthermore, the fabrication strategies of multifunctional perovskite photodetectors and their advancements are highlighted, including polarized light detection, spectral detection, angle-sensing detection, and self-powered detection. Finally, the existing problems of multifunctional detectors and the perspectives of their future development are presented. [ABSTRACT FROM AUTHOR]

The unprecedented development of perovskite solar cells (PSCs) makes them one of the most promising candidates for terawatt‐scale green energy production with low cost. However, the high boiling point solvents during the solution‐processed film deposition cause anisotropic crystal growth and toxic solvent vapor during high‐throughput manufacturing. Here, a dual‐component green solvent consisting of isopropyl acetate and acetonitrile is proposed to form a volatile perovskite precursor, which can realize the high‐quality perovskite thin film deposition by intermediate phase regulation. A room‐temperature stable perovskite intermediate phase is constructed with the engagement of isopropyl acetate as co‐solvent, which suppresses the exploding nucleation rate in volatile perovskite precursor, providing a fine grain growth rate and wide processing window in scalable film deposition. The corresponding PSCs fabricated by blade coating without anti‐solvents or gas quenching achieve power conversion efficiency (PCE) of 16.37 % and 15.29 % for the areas of 14.08 cm2 and 37.83 cm2, respectively. [ABSTRACT FROM AUTHOR]

The two‐step sequentially deposition strategy has been widely used to produce high‐performance FAPbI3‐based solar cells. However, due to the rapid reaction between PbI2 and FAI, a dense perovskite film forms on top of the PbI2 layer immediately and blocks the FAI diffusion into the bottom of the PbI2 film for a complete reaction, which results in a low‐efficiency and limited reproducibility of perovskite solar cells (PSCs). Here, high‐quality α‐FAPbI3 perovskite films by crystal growth regulation with 4‐fluorobenzamide additives is fabricated. The additives can interact with FAI to suppress the fast reaction between the FAI and PbI2 and effectively passivate the under‐coordinated Pb2+ or I‐ defects. As a result, α‐FAPbI3 perovskite films with low trap density and large grain size are prepared. The modified PSCs present a high‐power conversion efficiency of 24.08%, maintaining 90% of their initial efficiency after 1400 h in high humidity. This study provides an efficient strategy of synergistic crystallization and passivation to form high‐quality α‐FAPbI3 films for high‐performance PSCs. [ABSTRACT FROM AUTHOR]

Low‐dimensional Ruddlesden‐Popper (LDRP) perovskites still suffer from inferior carrier transport properties. Here, we demonstrate that efficient exciton dissociation and charge transfer can be achieved in LDRP perovskite by introducing γ‐aminobutyric acid (GABA) as a spacer. The hydrogen bonding links adjacent spacing sheets in (GABA)2MA3Pb4I13 (MA=CH3NH3+), leading to the charges localized in the van der Waals gap, thereby constructing "charged‐bridge" for charge transfer through the spacing region. Additionally, the polarized GABA weakens dielectric confinement, decreasing the (GABA)2MA3Pb4I13 exciton binding energy as low as ≈73 meV. Benefiting from these merits, the resultant GABA‐based solar cell yields a champion power conversion efficiency (PCE) of 18.73 % with enhanced carrier transport properties. Furthermore, the unencapsulated device maintains 92.8 % of its initial PCE under continuous illumination after 1000 h and only lost 3 % of its initial PCE under 65 °C for 500 h. [ABSTRACT FROM AUTHOR]

Intercalation regulation is a special way to tune the photophysical properties of perovskite without changing the organic cations. Here, it is found that dimethyl sulfoxide can be effectively intercalated into synthesized (OHC6H5CH2CH2NH3)2PbBr4 perovskite through hydrogen bonds between organic spacer layers and solvent molecules. The new intercalated perovskite can be stored for more than two months under a relative humidity of about 60% at room temperature without encapsulation. The single crystal microwire array device based on this special structure presents photoelectric response of a light on/off ratio of 400 under 365 nm irradiation at 3 V. The device has a low dark current of 10−13 A. Moreover, the inserted solvent molecules can be removed from the perovskite or reinserted into the perovskite under different processing conditions. The results show the potential to regulate the optoelectronic properties of perovskites by reversibly binding intercalated molecules with perovskites. [ABSTRACT FROM AUTHOR]

Advancing hole transport layers (HTL) to realize large‐area, flexible, and high‐performance perovskite solar cells (PSCs) is one of the most challenging issues for its commercialization. Here, a self‐assembled gradient Ti3C2Tx MXene incorporated PEDOT:PSS HTL is demonstrated to achieve high‐performance large‐area PSCs by establishing half‐caramelization‐based glucose‐induced MXene redistribution. Through this process, the Ti3C2Tx MXene nanosheets are spontaneously dispersed and redistributed at the top region of HTL to form the unique gradient distribution structure composed of MXene:Glucose:PEDOT:PSS (MG‐PEDOT). These results show that the MG‐PEDOT HTL not only offers favorable energy level alignment and efficient charge extraction, but also improves the film quality of perovskite layer featuring enlarged grain size, lower trap density, and longer carrier lifetime. Consequently, the power conversion efficiency (PCE) of the flexible device based on MG‐PEDOT HTL is increased by 36% compared to that of pristine PEDOT:PSS HTL. Meanwhile, the flexible perovskite solar minimodule (15 cm2 area) using MG‐PEDOT HTL achieve a PCE of 17.06%. The encapsulated modules show remarkable long‐term storage stability at 85 °C in ambient air (≈90% efficiency retention after 1200 h) and enhanced operational lifetime (≈90% efficiency retention after 200 h). This new approach shows a promising future of the self‐assembled HTLs for developing optoelectronic devices. [ABSTRACT FROM AUTHOR]

The solution process of perovskite solar cells may lead to widespread defects in the device, causing severe nonradiative recombination and the loss of conversion efficiency. Herein, a strategy of embedding thiourea into perovskite to manipulate the crystallization process and passivate the defects simultaneously is demonstrated. A competitive crystallization mechanism by embedding thiourea into perovskite has been proposed for the improvement of morphology and crystallinity. The defects in the device have been dramatically decreased by the strong coordination of CS bond in thiourea with the undercoordinated Pb2+. Moreover, the bilateral affinity of thiourea to the SnO2 and perovskite can enhance the interface contact by the bridging bonding, which will release the residual stress of perovskite films. As a result, the thiourea‐embedding device achieves a power conversion efficiency over 24% and shows excellent storage and illumination stabilities. Even undergoing 3768 h storage, the maximum efficiency value of unencapsulated device keeps over 94%. Furthermore, the efficiency of the optimized device maintains over 80% after 120 h continuous illumination at 60 °C. [ABSTRACT FROM AUTHOR]

Grain boundary cracks in flexible perovskite films can be repaired by filling with self‐repairing polymers during the preparation and wearable operation. However, the self‐repairing polymers are commonly active through external heating or humidification treatments, which cannot match with the human body's temperature tolerance of wearable devices. Herein, a body temperature‐responsive shape memory polyurethane (SMPU) is demonstrated to achieve the real‐time mechanical self‐repairing of grain boundary cracks (~37°C). Furthermore, the strong intermolecular interaction between SMPU and the uncoordinated Pb2+ and I−, can reduce the trap density in perovskite films. The blade‐coated device achieves a power conversion efficiency (PCE) of 21.33%, which is among the best reported flexible perovskite solar cells (PSCs; 0.10 cm2). Importantly, the device with SMPU can recover more than 80% of the PCE after 6000 cycles (bending radius: 8 mm). Finally, the flexible PSCs are used for wearable solar power supply of a smartphone, which show great potential for self‐repairing wearable electronics. [ABSTRACT FROM AUTHOR]

Defects at the interfaces of perovskite (PVK) thin films are the main factors responsible for instability and low photoelectric conversion efficiency (PCE) of PVK solar cells (PSCs). Here, a SnO2‐MXene composite electron transport layer (ETL) is used in PSCs to improve interfacial contact and passivate defects at the SnO2/perovskite interface. The introduced MXene regulates SnO2 dispersion and induces a vertical growth of PVK. The lattice matching of MXene and perovskite suppresses the concentration of interfacial stress, thereby obtaining a perovskite film with low defects. Compared with SnO2‐based device, the PCE of SnO2‐MXene‐based device is improved by 15 % and its short‐circuit current is up to 25.07 mA cm−2. Furthermore, unencapsulated device maintained about 90 % of its initial efficiency even after 500 h of storage at 30–40 % relative humidity in ambient air. The composite ETL strategy provides a route to engineer interfacial passivation between metal halide perovskites and ETLs. [ABSTRACT FROM AUTHOR]

Solution‐processed 2D perovskite films generally contain mixed quantum wells (QWs) with multiple well width distribution, which seriously weakens the charge transfer. To achieve regulation of the QW width, strategies to optimize the crystallization dynamics of 2D perovskite films are urgently needed. In this review, systematic summary on QW distribution and guidelines for 2D perovskite phase regulation is provided, aiming to establish a general manual for preparing efficient 2D perovskite solar cells (PSCs). The factors affecting the distribution of multiple‐QWs in 2D perovskite films, including component engineering, additive engineering, process optimization, are first generalized. Then an extensive review of these factors that are widely used to reconstruct 2D perovskite crystallization process is conducted. Leveraging these insights, the effect of QWs distributions on 2D PSCs properties is also summarized. Similarly, considering the crystallization kinetics and device performance, the QWs width control of 2D perovskite films from the aspects of ligand engineering, precursor design, and fabrication optimization, is rationalized. Finally, an outlook on how to realize ordered QWs distribution in perovskite films for efficient 2D PSCs is proposed. [ABSTRACT FROM AUTHOR]

Solution‐processed, high‐gain, and wavelength‐tunable perovskite single‐crystal microdisk (PVKsc‐MD) lasers have emerged as prospective coherent light sources in advanced nanophotonic designs. However, the inevitable multi‐directional emission from a highly symmetrical cavity leads to low light collection efficiency which greatly hinders its application in integrated optical circuits. Here, we report on surface‐patterned MAPbBr3 PVKsc‐MDs synthesized by a cost‐efficient bottom‐up solution process employing spin‐coating and confined‐growth nanoimprinting. The patterned microdisks have high crystal quality with regular shape and sharp edges and nano‐grating structure on the upper surface. This straightforward process yields surface‐patterned PVKsc‐MD lasers with a low lasing threshold and high quality (Q) factor. In addition, the grating structure patterned on the PVKsc‐MDs reduces the original symmetry of the laser cavity, which improves the emission directionality four times. [ABSTRACT FROM AUTHOR]

Pb‐based perovskite solar cells (PSCs) as one of the most promising photovoltaic technologies for commercialization have attracted tremendous attention in recent years. However, the toxicity and leakage of heavy metal Pb from perovskite film have become critical obstacles for eco‐friendly development. Extreme weather conditions such as heavy rain, high temperature, or strong sunlight may accelerate the undesired decomposition of perovskite film and cause inevitable Pb contamination in the ecosystem, which results in a potential threat to animals and the environment. In this review, guidelines for successfully managing Pb in PSCs are provided to open a pathway toward sustainable development. First, the toxicological research of Pb that can cause health problems for humans and contaminate the environment is discussed. Then, the decomposition mechanism of perovskite film and Pb leakage pathways under simulated environments in terms of moisture, high temperature, and illumination are briefly reviewed. Moreover, strategies to inhibit Pb leakage including physical sequestration, chemical adsorption, and Pb component substitution engineering are systematically summarized. Finally, different pathways for achieving the goal of Pb recycling and sustainable utilization are systematically analyzed. With a comprehensive understanding of these effects, rational strategies for sustainable Pb management can be made to accelerate the development of this emerging field. [ABSTRACT FROM AUTHOR]

Inorganic cesium lead iodide perovskite CsPbI3 is attracting great attention as a light absorber for single or multi‐junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non‐radiative recombination. Here, vacuum‐assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI3 perovskite films formed from the precursors of PbI2, CsI, and dimethylammonium iodide (DMAI). By this method, a large‐area and high‐quality CsPbI3 film is obtained, exhibiting a much reduced trap‐state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high‐performance thin‐film CsPbI3 perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

Metal halide perovskite, an emerging photosensitive semiconductor, has been widely employed in solar cells, light‐emitting diodes, photodetectors, and lasers owing to its excellent photophysical properties and simple solution preparation processing. However, as a photoactive layer, the higher refractive index and thinner thickness of perovskite film can cause reflection and transmission at the interface, and confine the emitted light within devices, resulting in the poor incident photon absorption and emitted photon extraction. In addition, the intrinsic brittleness of perovskite material restricts its potential applications in flexible optoelectronics. Therefore, great effort has been put into micro‐nano structured perovskite optoelectronics, and the reported reviews mainly focus on the fabrication process of micro‐nano patterned perovskite. Herein, the functionalities of micro‐nano structures in optoelectronics, including improving the light trapping, light extraction, light modulation, carrier dynamics, mechanical robustness, and other novel functionalities, are comprehensively reviewed. The specific applications of these functionalities in perovskite‐based optoelectronic devices are then discussed in detail to provide a better understanding of the photophysical properties of micro‐nano structure functionalized optoelectronics. Finally, promising strategies to promote the multifunctional commercial applications of micro‐nano structured perovskite optoelectronics are provided. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskite solar cells (PSCs) have attracted great attentions due to their rapid increase of power conversion efficiency (PCE). Although the highest PCE of PSCs (25.7%) has been achieved via using formamidinium lead iodide (FAPbI3) with a suitable bandgap, there is still a lack of systematic analysis on FAPbI3‐based PSCs toward high stability and high efficiency. Herein, the progress in FAPbI3 films and achievements in their high‐efficiency and long‐term stability PSCs are comprehensively reviewed. First, the progress from the aspects of morphology, defect, dimension, and strain for FAPbI3 film optimization is summarized and then the development of FAPbI3 PSCs in both efficiency and stability is discussed. Then, the methods to improve the FAPbI3 film quality by morphology control, defect passivation, dimensional regulation, and strain engineering, as well as strategies to optimize the device structure and interface layers, which are critical to promote device stability and efficiency, are evaluated. Finally, the outlook and strategies for realizing commercialized FAPbI3 PSCs with high efficiency and long lifetime are discussed. [ABSTRACT FROM AUTHOR]

Formamidinium (FA) based perovskites are considered as one of the most promising light‐absorbing perovskite materials owing to their narrower band gap and better thermal stability compared to conventional methylammonium‐based perovskites. Constant improvement by using various additives stimulates the potential application of these perovskites. Amine molecules with different structures have been widely used as typical additives in FA‐based perovskite solar cells, and decent performances have been achieved. Thus, a systematic review focusing on structural regulation and functional construction of amines in FA‐based perovskites is of significance. Herein, we analyze the construction mechanism of different structural amines on the functional perovskite crystals. The influence of amine molecules on specific perovskite properties including defect conditions, charge transfer, and moisture resistance are evaluated. Finally, we summarize the design rules of amine molecules for the application in high‐performance FA‐based perovskites and propose directions for the future development of additive molecules. [ABSTRACT FROM AUTHOR]

Perovskites as promising photovoltaic materials have been widely investigated due to their excellent photoelectric properties. Perovskite optoelectronic devices have been applied in fields of portable energy, light monitors, image sensors, etc. In recent years, wearable perovskite optoelectronic devices have been developed for their advantages of flexibility, stretchability, and light weight. In this review, the latest development of flexible and wearable perovskite optoelectronic devices is summarized. First, the preparation methods of optoelectronic devices are introduced, especially focusing on the large‐scale fabrication. Then the latest advances of various flexible devices are presented. In particular, the stability and safety of wearable devices, as well as the impact factors and corresponding solutions are discussed. Finally, the challenges for practical applications are put forward and discussed. [ABSTRACT FROM AUTHOR]

Real‐time in vitro detection of glioma cells facilitates precise tumor removal. However, the fluorescent labeling of tumor cells in clinical practice is limited by many factors, including the time consumed, low recognition efficiency, and fluorescence quenching. Here, a general strategy for building perovskite quantum dot (PQD)‐based biological probes utilizing the attraction between positive and negative electric charges is reported. Poly (lactic‐co‐glycolic acid) (PLGA) is chosen for encapsulating PQDs to completely prevent their aggregation, decomposition, or release in water or oxygen. The carboxyl group of PLGA has anchoring coordination with the PQDs, which reduces the surface defects. Moreover, it causes PQD‐based nanocrystals (P‐PNCs) to be surrounded by a positively charged layer in water. Given the specific recognition of chlorotoxin for the channels, rapid imaging of glioma cells is successfully performed in 15 min using P‐PNCs modified with chlorotoxin via charge attraction. The photoluminescence quantum yield of P‐PNC probes reached 87% and remained at 93% after 30 days of dispersion in water, while maintaining a much longer fluorescence lifetime of 15 µs. Therefore, this promising biological probe will be a general nanoplatform for identifying distinct cellular compartments using different biomarker imaging methods. [ABSTRACT FROM AUTHOR]

3D tin-based halide perovskites are promising light absorbers for perovskite solar cells (PSCs) due to their non-toxicity, suitable optical band gaps, and excellent optoelectronic properties. However, the inherent rapid crystallization and easy oxidation of Sn2+ to Sn4+ in 3D perovskites result in a low power conversion efficiency (PCE) and poor stability of tin perovskite solar cells compared with the lead counterparts. In this report, quasi-2D hybrid tin-based perovskite films are fabricated by using 2-thiopheneethylammonium (TEA+) as the spacer cation in MASnI3 (MA: CH3NH3+), leading to the formation of quasi-2D perovskite films with high orientation and a low content of Sn4+. As a result, the perovskite solar cells show a considerable power-conversion efficiency of 6.8%, which is among the highest values reported for MASnI3-based solar cells. Moreover, the devices exhibited excellent stability compared with the device without TEAI. [ABSTRACT FROM AUTHOR]

Although outstanding power conversion efficiency (PCE) has been achieved in flexible perovskite solar cells, unsatisfactory operational stability and toxicity caused by the moisture transmittance of polymer packaging are still the bottleneck challenges that limit their applications. Herein, inspired by the non‐selective permeability of inactivated cell membrane, the diphosphatidyl‐glycerol (Di‐g) is tactfully introduced as a self‐shield interface upon the perovskite layer. 96% of lead leakage is suppressed because the amphipathic Di‐g can simultaneously bind tightly to the divalent lead ion and afford an interfacial water‐resistance. More importantly, the gradient distribution of lattice residual stress perpendicular to the substrate are optimized. The resultant flexible devices achieve a PCE of 20.29% and 15.01% at effective areas of 1.01 and 21.82 cm2 respectively, yielding excellent environmental and mechanical stability. This strategy exhibits the feasibility of developing interfacial encapsulation to stabilize scalable PSCs with negligible lead leakage. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are promising photovoltaic technologies due to their impressive power conversion efficiency (PCE) and low‐temperature fabrication process, while it is still challenging to print uniform perovskite film with high crystalline quality over a module size. Here, a printable and stable perovskite nanocapsules ink to realize the high‐throughput printing of large‐area, highly uniform perovskite films with micron grain size is reported. It is discovered that the releasing effect of these perovskite nanocapsules promotes homogeneous nucleation by diffusion‐controlled growth due to the steady‐state diffusion of the solute in solution. Remarkably, the printed PSCs and 25 cm2 modules achieve power conversion efficiencies of 22.10% and 16.12%, respectively. They exhibit negligible efficiency loss after continuous operation for over 1000 h under AM1.5 illumination, and excellent thermal (85 °C) stability with over 87% of the initial efficiency after aging for 500 h. This perovskite nanocapsules ink is expected to facilitate the high‐yield fabrication of perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Perovskite (PVK) photodetectors (PDs) have emerged as highly‐efficient versatile optoelectrical devices due to their highly efficient and simple solution‐processable preparation method. Meanwhile, optical structures offer an efficient and facile strategy to improve the light‐harvesting performance of devices and introduce extra optical activity such as polarization sensitivity. Here, an efficient moiré perovskite photodetector with a stacked dual shallow grating structure is designed and fabricated, and sensitive digital polarization imaging is realized. The moiré PVK presents superior ability in light harvesting through the synergistic effects of feedback reflection, diffraction, and excitation of waveguide modes in the dual grating structure. Additionally, the highly crystalline PVK is fabricated through the imprint lithography process. Consequently, excellent device performance is achieved by taking advantage of highly‐efficient light‐harvesting and the good electrical properties of large grain PVK crystals. The responsivity (R) and detectivity (D*) of the moiré PVK PD are up to 15.62 A W and 5.58 × 1013 Jones, which are 6.7 and 7.8 times larger than that of the flat perovskite photodetector, respectively. The on/off ratio reaches 2.7 × 104. The nanograting array introduces good polarization sensitivity to the moiré PVK PD achieving a peak‐to‐valley ratio of 1.58. Excellent polarization images are obtained using a 576 pixel sensor array. [ABSTRACT FROM AUTHOR]

A low-temperature preparation process is significantly important for scalable and flexible devices. However, the serious interface defects between the normally used titanium dioxide (TiO2) electron transport layer (ETL) obtained via a low-temperature method and perovskite suppress the further improvement of perovskite solar cells (PSCs). Here, we develop a facile low-temperature chemical bath method to prepare a TiO2 ETL with tantalum (Ta) and niobium (Nb) co-doping. Systematic investigations indicate that Ta/Nb co-doping could increase the conduction band level of TiO2 and could decrease the trap-state density, boosting electron injection efficiency and reducing the charge recombination between the perovskite/ETL interface. A superior power conversion efficiency of 19.44% can be achieved by a planar PSC with a Ta/Nb co-doped TiO2 ETL, which is much higher than that of pristine TiO2 (17.60%). Our achievements in this work provide new insights on low-temperature fabrication of low-cost and highly efficient PSCs. [ABSTRACT FROM AUTHOR]

UV light always does great harm to perovskite solar cells, relentlessly degrading perovskites and shortening the lifetime of perovskite devices. Meanwhile, surface defects in perovskite films further accelerate the degradation process and serve as nonradiative charge recombination centers to deteriorate device efficiency. Herein, we demonstrate that a "sunscreen" molecule, 2‐hydroxy‐4‐methoxybenzophenone, not only protects the perovskite solar cell from UV degradation but also enables molecular defect passivation through interaction between functional groups and defects by molecular tautomerism under UV light illumination. Therefore, the sunscreen strategy efficiently enhances the UV endurance of PSCs and improves defect formation energy to −1.35 eV. The perovskite solar cell with sunscreen (sunscreen PSC) exhibits outstanding efficiencies of up to 23.09 % (0.04 cm2) and 19.73 % (1.00 cm2) as well as long‐term UV (UVa: 365 nm and UVb: 285 nm) stability. [ABSTRACT FROM AUTHOR]

A new crystal form of 1D perovskite (pyrrolidinium)PbI3 (orthorhombic phase) is synthesized and characterized. The 1D perovskite has a good film formability by solution spin coating and is in situ transformed to 3D CH3NH3PbI3 via the organic cation exchange approach in CH3NH2 atmosphere, which is dense and uniform. The converted 3D perovskite film is used as a light absorber, and the corresponding perovskite solar cell shows a power conversion efficiency of up to 19.2% under simulated 1 sun AM1.5G illumination (100 mW cm−2). [ABSTRACT FROM AUTHOR]

The low toxicity, narrow bandgaps, and high charge‐carrier mobilities make tin perovskites the most promising light absorbers for low‐cost perovskite solar cells (PSCs). However, the development of the Sn‐based PSCs is seriously hampered by the critical issues of poor stability and low power conversion efficiency (PCE) due to the facile oxidation of Sn2+ to Sn4+ and poor film formability of the perovskite films. Herein, a synthetic strategy is developed for the fabrication of methylammonium tin iodide (MASnI3) film via ion exchange/insertion reactions between solid‐state SnF2 and gaseous methylammonium iodide. In this way, the nucleation and crystallization of MASnI3 can be well controlled, and a highly uniform pinhole‐free MASnI3 perovskite film is obtained. More importantly, the detrimental oxidation can be effectively suppressed in the resulting MASnI3 film due to the presence of a large amount of remaining SnF2. This high‐quality perovskite film enables the realization of a PCE of 7.78%, which is among the highest values reported for the MASnI3‐based solar cells. Moreover, the MASnI3 solar cells exhibit high reproducibility and good stability. This method provides new opportunities for the fabrication of low‐cost and lead‐free tin‐based halide perovskite solar cells. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic perovskite solar cells have attracted considerable attention over the past decade, delivering high power conversion efficiencies over 25%. There still exist challenges regarding precisely regulating perovskite crystallization kinetics due to the random nucleation and disordered diffusion growth in the spontaneous solution chemical reaction process, subsequently leading to poor film quality with chaotic microstructure arrangement and undesired defect states which compromises the photovoltaic performance. Recently, the research priority in the perovskite photovoltaic community has put emphasis on seed templates driving controllable growth of perovskite film, triggering excitement for novel manufacturing technologies. Herein, we provide a systematic overview covering the current pioneering works to comprehend the advances of seed template regulation approaches and the underlying mechanism in terms of microstructure evolution and optoelectronic properties. The intense search regarding constructing representative perovskite single and polycrystalline crystals is provided to elaborate on the prominent roles of seed templates. [Display omitted] • In-depth theoretical mechanisms regarding heteroepitaxial growth and advanced regulation strategies are provided. • Conceptual insights into structural properties in perovskite polycrystals are proposed. • The promising progress regarding controlling over the perovskite single crystals growth is introduced. [ABSTRACT FROM AUTHOR]

Extensive applications for photodetectors have led to demand for high‐responsivity polarization‐sensitive light detection. Inspired by the elaborate architecture of butterfly Papilio paris, a 1D nanograting bonded porous 2D photonic crystal perovskite photodetector (G‐PC‐PD) using a commercial DVD master and 2D crystalline colloidal arrays template was fabricated. The coupling effect from grating diffraction and reflection of the PC stopband renders the enhanced light harvesting of G‐PC‐PD. The porous scaffold and nanoimprinting process afford a highly crystalline perovskite film. White light responsivity and detectivity of G‐PC‐PD are up to 12.67 A W−1 and 3.22×1013 Jones (6∼7 times that of a pristine perovskite photodetector). The highly ordered nanograting arrays of G‐PC‐PD enable polarization‐sensitive light detection with a rate of −0.72 nA deg−1. This hierarchical perovskite integrated nanograting and 2D PC architecture opens a new avenue to high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Methylammonium bismuth iodide (MA3Bi2I9) has been recently investigated as a light absorber in lead-free perovskite solar cells. However, the MA3Bi2I9 film fabricated via conventional one-step spin coating methods usually has poor surface morphology, limiting the device performance. Herein, a cation displacement approach was employed for the fabrication of MA3Bi2I9 film, where (CH3CH2CH2NH3)3Bi2I9 (PA3Bi2I9) film was first deposited from a solution containing CH3CH2CH2NH3I and BiI3 and then transformed into MA3Bi2I9 film in a methylamine atmosphere. With the technique, the MA3Bi2I9 film was realized with smooth, uniform, and compact surface morphology. Using the MA3Bi2I9 film as a light absorber, a mesoporous photovoltaic device was fabricated with a power conversion efficiency of 0.33%, which is about two times higher than the value (0.15%) obtained for the one-step spin coating MA3Bi2I9 device. Moreover, the facile film fabrication strategy utilized in this work paves the way for high reproducibility of lead-free organic–inorganic halide films and devices. [ABSTRACT FROM AUTHOR]

Tin‐based halide perovskite materials have been successfully employed in lead‐free perovskite solar cells, but the overall power conversion efficiencies (PCEs) have been limited by the high carrier concentration from the facile oxidation of Sn2+ to Sn4+. Now a chemical route is developed for fabrication of high‐quality methylammonium tin iodide perovskite (MASnI3) films: hydrazinium tin iodide (HASnI3) perovskite film is first solution‐deposited using presursors hydrazinium iodide (HAI) and tin iodide (SnI2), and then transformed into MASnI3 via a cation displacement approach. With the two‐step process, a dense and uniform MASnI3 film is obtained with large grain sizes and high crystallization. Detrimental oxidation is suppressed by the hydrazine released from the film during the transformation. With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility. [ABSTRACT FROM AUTHOR]

Inspired by light/sound trapping in whispering-gallery, a light trapping structure mimicking whispering-gallery (WG) structure is constructed on perovskite active layer for antireflection and light harvesting via simply imprinted process with robust microstructure stamp for perovskite solar cells (PSCs). The WG structured perovskite films can achieve light trapping by optical feedback and gradually absorption. The crystallization and size of perovskite are improved by the imprinting process with robust micro-patterned stamp. Moreover, this method can efficiently accelerate electron-hole separation and suppress recombination by extract tentacles of the arrayed column structure. Consequently, the power conversion efficiency of the whispering-gallery structured PSC is improved to 19.80%, which is ca. 29.4% higher than that of the non-imprinted PSC (15.30%). [ABSTRACT FROM AUTHOR]

Abstract: Achieving light harvesting is crucial for the efficiency of the solar cell. Constructing optical structures often can benefit from micro‐nanophotonic imprinting. Here, a simple and facile strategy is developed to introduce a large area grating structure into the perovskite‐active layer of a solar cell by utilizing commercial optical discs (CD‐R and DVD‐R) and achieve high photovoltaic performance. The constructed diffraction grating on the perovskite active layer realizes nanophotonic light trapping by diffraction and effectively suppresses carrier recombination. Compared to the pristine perovskite solar cells (PSCs), the diffraction‐grating perovskite devices with DVD obtain higher power conversion efficiency and photocurrent density, which are improved from 16.71% and 21.67 mA cm−2 to 19.71% and 23.11 mA cm−2. Moreover, the stability of the PSCs with diffraction‐grating‐structured perovskite active layer is greatly enhanced. The method can boost photonics merge into the remarkable perovskite materials for various applications. [ABSTRACT FROM AUTHOR]

The structural advantages and localized surface plasmon resonance (LSPR) effect of Ag@SiO2 nanowires when used as plasmonic antennas possess the features of fast electron transmission by 1D metal nanomaterials, high light harvesting, and electron-hole separation through the LSPR effect. By optimizing the concentration of Ag@SiO2 nanowires (0.06 wt%) in the active layer of a device, high power conversion efficiency of 18.03% and a negligible photocurrent hysteresis are obtained. [ABSTRACT FROM AUTHOR]

The brittleness of perovskite (PVK) film restrains the development and application of the flexible perovskite solar cells (FPSCs). We utilize the polyurethane elastomers with disulfide bonds (PUDS) as a self-healing polymer to construct self-healing FPSCs and strengthen the self-healed perovskite film by the phase-locked state. The PUDS efficiently enhances the flexibility and self-healing properties of FPSCs. The champion efficiencies of MAPbI 3 on rigid and flexible substrates with PUDS are 20.30% and 17.19%, respectively. Importantly, the efficiency of cracked FPSC after thermal self-healing (80 °C) has been recovered from 12% (Broken: 2.06%) of the initial efficiency (17.19%) to 88% (Recovery: 15.12%). Besides, the efficiency of FPSC with PUDS maintains 95% of the initial value after 3000 h stored in glove box. This strategy provides an effective approach for developing flexible electronics. [Display omitted] • Polyurethane with disulfide bonds achieve the self-healing flexible perovskite solar cells by the phase-locked dynamic bonds. • The dynamic bonds of PUDS transform to the phase-locked state strengthening the self-healed perovskite film. • The efficiency of the cracked FPSC recovers from 12% (Broken: 2.06%) to 88% (Recovery: 15.12%) of the initial efficiency (17.19%) after the multiple bending-heal. • The FPSC with PUDS maintains 84% of the initial PCE after 4000 bending cycles at the radius of 3 mm. [ABSTRACT FROM AUTHOR]

The unique properties of metal halide perovskites give them great potential for applications in portable and wearable optoelectronics. However, the intrinsic brittleness of perovskites favors easy crack propagation that deteriorates the optoelectronic performance of the devices. Inspired by nacre, we propose flexible perovskite thin films fabricated by antisolvent-assisted self-encapsulation of polymer and imprinting techniques during crystallization. Such an approach results in synchronous formation of polymer-glued perovskite grains exhibiting nacre-like "brick-and-mortar" structure. The deformable composite architecture bonding hemisphere-shaped grating (HG) and porous photonic crystal (PC) (HG-PC) improves its crystalline quality and light-harvesting capability. An HG-PC photodetector (PD) with high responsivity of 17.31 A/W and detectivity of 5.02 × 1013 Jones is achieved. Our flexible HG-PC PD retains 95% of the initial photocurrent after 1000 bending cycles at 2 mm curvature radius. This solvent-driven self-encapsulation strategy offers an innovative and universal approach for highly efficient flexible optoelectronics. [Display omitted] • The synergistic effect of "brick-and-mortar" structure and deformable photonic architecture endows flexible perovskite photodetector with high mechanical robustness and durability • A perovskite photodetector with high responsivity of 17.31 A/W and detectivity of 5.02 × 1013 Jones is achieved. [ABSTRACT FROM AUTHOR]

• The evolution of 2D perovskites based on multi-characteristic organic spacers is approached. • Impacts of the organic spacers on photophysical properties and film quality of 2D perovskites are discussed. • Several strategies to select and optimize the organic spacers for enhancing photovoltaic characteristics are proposed. [Display omitted] Two-dimensional (2D) perovskites have been attracting extensive attention due to their intrinsic stability compared with their three-dimensional (3D) counterparts. These materials are widely tailorable in composition, structure, and bandgap, and provide an intriguing playground for the solid-state chemistry and physics communities to uncover structure-property relationships. In the field of photovoltaic, the fabricated 2D perovskite solar cells (PSCs) have achieved high stability as well as sustainable breakthrough in power conversion efficiency (PCE). However, the PCE of 2D PSCs still lags far behind their 3D counterpart, which is attributed to the special physicochemical properties of organic ligands. This review focuses the 2D halide perovskites from a structural perspective, namely the Ruddlesden-Popper (RP) phases, Dion-Jacobson (DJ) phases, alternating cation in the interlayer space (ACI) phases and mixed organic ligands phases, which stems from the diversity and versatility of spacers. Then the impacts of the species, chemical compositions, and physical characteristics of spacers on 2D perovskites, especially on the structure, carrier behavior, and the specific properties of solar cells, were discussed. Finally, several strategies on the rational selection of novel spacers are elucidated, and an outlook toward high-performance of 2D PSCs is presented. [ABSTRACT FROM AUTHOR]

Perovskites, solar cells, tautomerism, UV stability Rücktitelbild: Tautomeric Molecule Acts as a "Sunscreen" for Metal Halide Perovskite Solar Cells (Angew. Keywords: perovskites; solar cells; tautomerism; UV stability EN perovskites solar cells tautomerism UV stability 9228 9228 1 04/03/21 20210412 NES 210412 B UV-Licht und Oberflächendefekte b beschleunigen den Degradationsprozess von Perowskit-Solarzellen (PSCs). [Extracted from the article]