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Moisture is a double‐edged sword in the nucleation and crystallization of perovskite films. In the presence of appropriate moisture in the air, grain boundaries are expected to merge neighboring grains, promoting the conversion of unreacted ions, resulting in large grains and pinhole‐free films. Adversely, excessive moisture can have detrimental effects on perovskite by damaging its crystalline structure. Controlling humidity precisely and removing excessive moisture from the interface is crucial to the printing of high‐quality and reproducible films in the air, which will undoubtedly promote the rapid commercialization of perovskite solar cells. Here, a method for high‐yield printing of perovskite films is developed using interfacial moisture as a research object. The finite element simulation reveals that interfacial moisture is the key factor affecting the quality of perovskite film formation, regardless of the ambient moisture. The results show that when the interfacial humidity is in the range of 7%–25%, the films exhibit high‐quality crystallization. The devices produced by this method exhibit a yield of 92%, indicating a promising pathway to attain highly reproducible perovskite films with superior optoelectronic properties. The air‐printing process will provide a broad guide to the commercial manufacture of high‐performance perovskite optoelectronic devices. [ABSTRACT FROM AUTHOR]

Targeting the trap‐assisted non‐radiative recombination losses and photochemical degradation occurring at the interface and bulk of perovskite, especially the overlooked buried bottom interface, a strategy of tailored‐phase two‐dimensional (TP‐2D) crystal seed layer has been developed to improve the charge transport dynamics at the buried interface and bulk of perovskite films. Using this approach, TP‐2D layer constructed by TP‐2D crystal seeds at the buried interface can induce the formation of homogeneous interface electric field, which effectively suppress the accumulation of charge carriers at the buried interface. Additionally, the presence of TP‐2D crystal seed has a positive effect on the crystallization process of the upper perovskite film, leading to optimized crystal quality and thus promoted charge transport inside bulk perovskites. Ultimately, the best performing PSCs based on TP‐2D layer deliver a power conversion efficiency of 24.58 %. The devices exhibit an improved photostability with 88.4 % of their initial PCEs being retained after aging under continuous 0.8‐sun illumination for 2000 h in air. Our findings reveal how to regulate the charge transport dynamics of perovskite bulk and interface by introducing homogeneous components. [ABSTRACT FROM AUTHOR]

Over the last decade, perovskite solar cells (PSCs) have drawn extensive attention owing to their high power conversion efficiency (single junction: 26.1%, perovskite/silicon tandem: 33.9%) and low fabrication cost. However, the short lifespan of PSCs with initial efficiency still blocks their practical applications. This operational instability may originate from the intrinsic and extrinsic degradation of materials or devices. Although the lifetime of PSCs has been prolonged through component, crystal, defect, interface, encapsulation engineering, and so on, the systematic analysis of failure regularity for PSCs from the perspective of materials and devices against multiple operating stressors is indispensable. In this review, we start with elaboration of the predominant degradation pathways and mechanism for PSCs under working stressors. Then the strategies for improving long‐term durability with respect to fundamental materials, interface designs, and device encapsulation have been summarized. Meanwhile, the key results have been discussed to understand the limitation of assessing PSCs stability, and the potential applications in indoor photovoltaics and wearable electronics are demonstrated. Finally, promising proposals, encompassing material processing, film formation, interface strengthening, structure designing, and device encapsulation, are provided to improve the operational stability of PSCs and promote their commercialization. [ABSTRACT FROM AUTHOR]

Polymer matrix is felicitously applied into the active layer and transporting layer of perovskite solar cells (PSCs) to enable a stretchable function. However, the chaotic deposition of polymer chains is the main cause for the inferior photoelectric performance. When the stretchable PSCs are in a working state, the stress cannot be removed effectively due to the random polymer chain deposition. The stress accumulation will cause irreversible damage to the stretchable PSCs. Herein, the structural bionics and patterned‐meniscus coating technology are combined to print the polymer chain‐oriented deposition in the stretchable PSCs. Based on this approach, the conducting polymer electrode is printed with both significant mechanical stability and conductivity. More importantly, the oriented polyurethane with self‐healing property can enhance the crystal quality of perovskite films and repair perovskite cracks caused by stress destruction. Thus, the corresponding stretchable PSCs achieve a stabilized power conversion efficiency (PCE) of 20.04% (1.0 cm2) and 16.47% (9 cm2) with minor efficiency discrepancy. Notably, the stretchable PSCs can maintain 86% of the primitive PCE after 1000 cycles of bending with a stretch ratio of 30%. This directional growth of polymer chain strategy provides guidance for printing prominent‐performance stretchable PSCs. [ABSTRACT FROM AUTHOR]

The multiple quantum wells (QWs) distribution in low‐dimensional perovskite films hinders charge transport due to the fundamental difficulty of controlling crystal growth from precursor solutions, yielding poorly homogeneous low‐dimensional perovskite solar cells (PSCs), especially in upscaling fabrication. Here, efficient low‐dimensional PSCs are realized by modulating the colloidal assembly behavior in the precursor solution to induce intermediate structures. In combination with in situ liquid time‐of‐flight secondary ion mass spectrometry, the assembly behavior of organic cations involved lead iodide‐dominated colloidal soft framework is visualized by investigating the precursor species differences under hydrogen bonding interactions. Subsequently, solid‐state reactions emerge and the formamidine (FA)‐based perovskite films exhibit significantly suppressed multiple QWs distribution. Encouragingly, the FA device (n=9, by meniscus‐assisted coating) achieves a power conversion efficiency (PCE) of 20.28 % for a size of 0.04 cm2 and a PCE of 15.35 % for a mini‐module of 16.94 cm2 with superior stability. [ABSTRACT FROM AUTHOR]

Highlights: The strategy of imprint assisted with methylamine acetate effectively ameliorates the morphology of the film, optimize the internal phase distribution, and enhance the charge transfer of the perovskite film. The combination of imprinting with additive engineering improves the phase distribution within quasi-2D perovskite and promote the carrier transport, resulting in a power conversion efficiency of 18.96% with specific good reproducibility. Although two-dimensional perovskite devices are highly stable, they also lead to a number of challenges. For instance, the introduction of large organic amines makes crystallization process complicated, causing problems such as generally small grain size and blocked charge transfer. In this work, imprint assisted with methylamine acetate were used to improve the morphology of the film, optimize the internal phase distribution, and enhance the charge transfer of the perovskite film. Specifically, imprint promoted the dispersion of spacer cations in the recrystallization process with the assistance of methylamine acetate, thus inhibited the formation of low-n phase induced by the aggregation of spacer cations and facilitated the formation of 3D-like phase. In this case, the corresponding quasi-2D perovskite solar cells delivered improved efficiency and exhibited superior stability. Our work provides an effective strategy to obtain uniform phase distribution for quasi-2D perovskite. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The preparation of perovskite solar cells (PSCs) in the air environment has attracted the attention of numerous experimenters due to its low preparation cost and the possibility of commercialization. Although the power conversion efficiency (PCE) of PSCs has increased rapidly and exceeded 25%, which is comparable to commercial polysilicon solar cells, most certified or reported high‐efficiency perovskite solar cells are still confined to glove boxes or relatively small active areas in the air environment due to moisture, oxygen, high temperature, and ultraviolet (UV) factors. In this review, the factors that lead to perovskite degradation are reviewed, and the appropriate strategies for manufacturing high‐efficiency and stable perovskite solar cells under environmental conditions are summarized to help the technology be commercialized for high‐quality, stable, and large‐area perovskite thin films in the air. [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]

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]

Meniscus‐coating as a high‐throughput preparation process has significant advantages in the manufacture of large‐area perovskite solar cells (PSCs). However, the gradient crystallization during printing significantly affects the vertical uniformity of perovskite films, which greatly affects the carrier transport of perovskite films and the stability of PSCs. Here, a perovskite ink compatible with printing technology is reported to realize uniform printing of perovskite film on a 3D scale. The siloxane 3D network hinders the solute migration caused by capillary force and acts as a skeleton to promote the uniform crystallization of perovskite films. Consequently, the corresponding fully printed PSCs have reduced efficiency loss (from 37.4% to 17.0%). In addition, based on the improvement of crystal quality and reduction of defects in perovskite films, the siloxane‐optimized PSCs achieved a championship efficiency of 22.0%, which is one of the highest performance for fully printed devices. The optimized device retains 80% of the initial PCE after 800 h AM 1.5G one‐sun illumination, and only decreases 20% after 160 h of ultraviolet light (365 nm, 20 mW cm−2) irradiation. [ABSTRACT FROM AUTHOR]

Defects in perovskite films and the suboptimal interface contact largely limit the performance and stability of inverted perovskite solar cells (PSCs). A simple surface post‐treatment with N‐benzyloxycarbonyl‐d‐valine (NBDV) is developed to overcome these problems. The device performance following NBDV treatment is systemically investigated. It is showed that NBDV surface post‐treatment results in the bulk restructure of the entire perovskite film and improves the film‐forming property of [6,6]‐phenyl‐C61‐butyric acid methyl ester. The grain sizes, crystallinity, trap states, cathode interfaces, as well as the built‐in field are also improved, which result in PSC performance and stability enhancement. A relatively higher power conversion efficiency (PCE) of 21.80% is reached, which is comparable to the PCE record based on single‐crystal MAPbI3. Meanwhile, the PCE of the NBDV devices can retain ≈77% and 84% of the initial value after storage for 768 h (32 days) in air and 8376 h (349 days) in N2, respectively, while the control devices only maintain ≈53% and 38% of their initial PCE values under the same exposure conditions. This work provides means to promote bulk, surface, and interface regulation toward high performance and stable inverted PSCs. [ABSTRACT FROM AUTHOR]

Solution processing of perovskite solar cells (PSCs) is highly promising for the high‐throughput production of cost‐effective devices. Although PSCs have achieved great advances in power conversion efficiency, challenges still remain in the reproducibility of high‐quality perovskite thin film with simultaneously improved precursor solution stability. Here, a reactive inhibition strategy by introducing diethyl (hydroxymethyl) phosphonate (DHP) in perovskite precursor solution is successfully employed to improve the stability of precursor solution and the performance of corresponding device. DHP inhibits the reactivity of the iodide and formamidinium ions through multiple chemical bonds, ensuring the stability of the precursor solution. In addition, due to chelation interaction of Pb2+ with the oxygen of PO in DHP, the DHP in the perovskite film improves the film quality with desired stoichiometry by reducing the defects and the content of lead iodide. The DHP‐doped precursor solution and corresponding devices show excellent performance reproducibility and super stability under ambient conditions for more than 50 days, which illustrates the commercial feasibility for scalable fabrication. [ABSTRACT FROM AUTHOR]

The control of crystallization and printability of large‐area perovskite layers is crucial to facilitating their commercial development in flexible electronics. Considering the benefits of the liquid crystals with intelligent temperature sensitivity for the printable and crystalline template of a scalable perovskite film, a liquid crystal 4((6(acryloyloxy)hexyl)oxy)benzoic acid (6OBA) is introduced. The 6OBA shows a liquid crystal temperature range matching with the thermal annealing temperature of perovskite films. A desire printability of perovskite inks for scalable and homogeneous devices is guaranteed due to the fluidity of the 6OBA additive at room temperature. Moreover, the crystalline 6OBA promotes crystallization of perovskite films during the thermal annealing process, which can also release the residual stress of the whole layer. The optimized perovskite solar cells (PSCs) with 6OBA exhibit superior power conversion efficiency values of 19.87% for flexible devices (1.01 cm2) and 14.74% for flexible modules (25 cm2). The unencapsulated devices can maintain >90% of their original efficiency after 1500 h in the ambient atmosphere. Furthermore, the flexible PSCs exhibit outstanding bending resistance, retaining over 88% of their initial efficiency after 1000 bending cycles at a radius of 3 mm. This work provides a facile strategy for accelerating the development of flexible electronics. [ABSTRACT FROM AUTHOR]

The potential leakage of lead from degraded perovskite photovoltaics poses a threat to the ecosystem and human health, which is a severe hurdle for their commercialization, especially for flexible modules that are often integrated in applications used in daily living. To trap the lead from degraded flexible perovskite solar modules (PVSMs), sulfonated graphene aerogels mixed with polydimethylsiloxane are employed to serve as lead‐absorbing encapsulants on both sides of flexible PVSMs. The large specific area of sulfonated graphene aerogels and their high binding energy with Pb2+ give them superior lead adsorption capacity in aqueous solution. Over 99% of Pb2+ from the degraded flexible PVSMs can be captured by the encapsulant under different simulated conditions (scratching, bending, and thermal circling) to reduce the lead leakage to ≈10 ppb. Moreover, the lead from degraded flexible PVSMs can be minimized to far below the hazardous waste limit according to the resource conservation and recovery act regulation (RCRA). This work provides an effective strategy to realize safe‐to‐use perovskite‐based flexible electronics to facilitate their commercialization. [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]

Homogeneity and stability of flexible perovskite solar cells (PSCs) are significant for the commercial feasibility in upscaling fabrication. Concretely, the mismatching between bottom interface and perovskite precursor ink can cause uncontrollable crystallization and undesired dangling bonds during the printing process. Herein, methylammonium acetate, serving as ink assistant (IAS) can effectively avoid the micron‐scale defects of perovskite film. The in situ optical microscope is applied to prove the IAS can inhibit the colloidal aggregation and induce more adequate crystallization growth, thus avoiding the micron‐scale defects of pinholes and intergranular cracking. Concurrently, 4‐chlorobenzenesulfonic acid is introduced into the electrode surface as a passivation layer to restore the deep traps at perovskite interface in nano‐scale. Finally, the target flexible devices (1.01 cm2) deliver a superior efficiency of 18.12% with improved air atmosphere stability. This multi‐scale defect repair strategy provides an integrated design concept of homogeneity and stability for scalable and flexible PSCs. [ABSTRACT FROM AUTHOR]

As one of the most promising hole transport layers (HTLs), nickel oxide (NiOx) has received extensive attention due to its application in flexible large‐area perovskite solar cells (PSCs). However, the poor interface contact caused by inherent easy‐agglomeration phenomenon of NiOx nanoparticles (NPs) is still the bottleneck for achieving high‐performance devices. Herein, a general strategy to synthesize NiOx NPs with high crystallinity and good dispersibility via the polymer network micro‐precipitation method is reported. Promisingly, this approach realizes the flow‐division of precipitant and the restraint of the NPs motion, thereby effectively alleviating the coagulation phenomenon caused by excessive local concentration and secondary movement adsorption. Furthermore, the addition of ionic liquid not only inhibits the secondary aggregation of NiOx NPs during the dispersion process, but also significantly enhances the properties of the colloidal solution. Ultimately, the 1.01 cm2 PSCs based on the optimized NiOx HTLs achieve the champion power conversion efficiency of 20.91% and 19.17% on rigid and flexible substrates, respectively. Moreover, the reproducibility and stability of PSCs are also significantly improved, especially for flexible devices. Overall, this strategy provides the possibility for flexible, large‐area fabrication of high‐quality NiOx HTLs to promote the development of stable and efficient perovskite devices. [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]

Solar cells based on organometal halide perovskites attract increasing research interest as an excellent source of renewable energy due to their inexpensive process, high power conversion efficiency, and availability of abundant raw material. The basic description, current research targets and status, and future perceptions of perovskite‐based photovoltaics along with the strategies toward the enhancement of both (intrinsic and extrinsic) stabilities of high‐efficiency devices are summarized and analyzed. This review provides the required knowledge for this design by studying various commercialized thin‐film technologies, analyzing large‐scale fabrication methods like physical vapor deposition, chemical vapor deposition, inkjet printing, doctor blading, spray coating, and roll‐to‐roll techniques. Addressing the present threat and opportunities for integrating the new material exploration, devices and large‐scale fabrication is conductive to the successful commercialization of the perovskite solar cells (PVSCs). This article presents the overview of the reports of the latest technological enhancement of cell stability, interfacial modification, replacement of electron and hole transport layers, techniques used for minimizing the lead‐based perovskites toxicity, and large‐scale fabrication. Finally, this provides an emphasis on organometal halide perovskite‐based solid‐state solar cell contacts that are believed to be the key factor for achieving highly stable PVSCs. [ABSTRACT FROM AUTHOR]

A washable perovskite solar cell with high efficiency (over 11%) and outstanding crumpling durability (maintaining 81.2% after 100 cycles crumpling) is demonstrated herein by combining the flexible self-encapsulation method with a waterproof glue coated substrate. [ABSTRACT FROM AUTHOR]

Tin‐based perovskite solar cells (PSCs) demonstrate a potential application in wearable electronics due to its hypotoxicity. However, poor crystal quality is still the bottleneck for achieving high‐performance flexible devices. In this work, graphite phase‐C3N4 (g‐C3N4) is applied into tin‐based perovskite as a crystalline template, which delays crystallization via a size‐effect and passivates defects simultaneously. The double hydrogen bond between g‐C3N4 and formamidine cation can optimize lattice matching and passivation. Moreover, the two‐dimensional network structure of g‐C3N4 can fit on the crystals, resulting an enhanced hydrophobicity and oxidation resistance. Therefore, the flexible tin‐based PSCs with g‐C3N4 realize a stabilized power conversion efficiency (PCE) of 8.56 % with negligible hysteresis. In addition, the PSCs can maintain 91 % of the initial PCE after 1000 h under N2 environment and keep 92 % of their original PCE after 600 cycles at a curvature radius of 3 mm. [ABSTRACT FROM AUTHOR]

Sulfonated graphene oxide (s-GO) is employed to form the cementitious GBs, which passivates the defects of V I and enhances the ductility of perovskites. The as-optimized flexible PSCs shows a record PCE of 20.56% for 1.01 cm2 and exhibits excellent flexibility, which retains about 88% efficiency even the bending angle reaches 70 degree [Display omitted] The power conversion effciency (PCE) of flexible perovskite solar cells (PSCs) has increased rapidly, while the mechanical flexibility and environmental stability are still far from satisfactory. Previous studies show the environmental degradation and ductile cracks of perovskite films usually begin at the grain boundaries (GBs). Herein, sulfonated graphene oxide (s-GO) is employed to construct a cementitious GBs by interacting with the [PbI 6 ]4– at GBs. The resultant s-GO-[PbI 6 ]4– complex can effectively passivate the defects of vacant iodine, and the devices with s-GO exhibit remarkable waterproofness and flexibility due to the tough and water-insoluble GBs. The champion PCE of 20.56% (1.01 cm2) in a device treated with s-GO is achieved. This device retains 90% of its original PCE after 180 d stored in the ambient condition, as well as over 80% retention after 10,000 bending cycles at a curvature radius of 3 mm. [ABSTRACT FROM AUTHOR]

In recent years, the development of perovskite solar cells (PSCs) is advancing along the way, and the efficiency is comparable to traditional silicon‐based solar cells. However, as crucial factors in the road to commercialization, stability and upscaling manufacture have not been fully investigated yet. To solve these problems, the exploration of charge transport layer (CTL) is clearly imminent, which is critical to the stability of PSCs. Among them, inorganic metal oxides have better stability than organic CTL. Particularly, the atomic layer deposition (ALD) process can fabricate dense and scalable metal oxides based on the self‐limiting surface reaction. This perspective focuses on the recent progress of ALD‐grown metal oxides in PSCs: both of electron and hole transport layer; connection layer in tandem architectures; application in semi‐transparent perovskite solar cells (ST‐PSCs); prospective of commercialization feasibility of the ALD‐grown metal oxides in ST‐PSCs. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are a promising photovoltaic technology for stretchable applications because of their flexible, light‐weight, and low‐cost characteristics. However, the fragility of crystals and poor crystallinity of perovskite on stretchable substrates results in performance loss. In fact, grain boundary defects are the "Achilles' heel" of optoelectronic and mechanical stability. We incorporate a self‐healing polyurethane (s‐PU) with dynamic oxime–carbamate bonds as a scaffold into the perovskite films, which simultaneously enhances crystallinity and passivates the grain boundary of the perovskite films. The stretchable PSCs with s‐PU deliver a stabilized efficiency of 19.15 % with negligible hysteresis, which is comparable to the performance on rigid substrates. The PSCs can maintain over 90 % of their initial efficiency after 3000 hours in air because of their self‐encapsulating structure. Importantly, the self‐healing function of the s‐PU scaffold was verified in situ. The s‐PU can release mechanical stress and repair cracks at the grain boundary on multiple levels. The devices recover 88 % of their original efficiency after 1000 cycles at 20 % stretch. We believe that this ingenious growth strategy for crystalline semiconductors will facilitate development of flexible and stretchable electronics. [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]

Solar cells based on mixed organic-inorganic halide perovskites are promising photovoltaic technologies with low-cost and fantastic power conversion efficiency (PCE). Enhancing the nucleation and regulating the crystallization rate of perovskite films and improving the bendability of brittle hybrid grains are crucial to improving the photovoltaic performance of flexible perovskite solar cells (PVSCs). Here, a simple approach is first introduced for fabricating perovskite films with full coverage and larger crystalline size by incorporating the elastomer polyurethane (PU) into the perovskite precursor solution to both retard the crystallization rate and improve the bendability. Shiny, smooth perovskite films are obtained with compact, micrometer-sized crystalline grains that exhibit excellent photoelectric performances. The PVSCs fabricated by incorporating PU into the perovskite precursor offer an impressive PCE of 18.7% with almost no photocurrent hysteresis and excellent stability in ambient air. More importantly, the elastomer PU additive crosslinks the grain boundaries between neighboring perovskite crystals to form a PU network that effectively improves the bendability of the perovskite films. [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 grain size of perovskites was enhanced and the grain boundary was filled with sulfonate carbon nanotubes (s-CNTs) during the CH3NH3PbI3 perovskite precursor solution spin-coating process with the incorporation of s-CNTs. The performance of s-CNT incorporated perovskite solar cells remarkably increased from 10.3% to 15.1% (best) compared with pristine CNT incorporated perovskite solar cells. [ABSTRACT FROM AUTHOR]

Hole transporting layer (HTL)-free CH 3 NH 3 PbI 3 /PC 61 BM planar heterojunction perovskite solar cells were fabricated with the configuration of ITO/CH 3 NH 3 PbI 3 /PC 61 BM/Al. The devices present a remarkable power conversion efficiency (PCE) of 11.7% (12.5% best) under AM 1.5G 100 mW cm −2 illumination. Moreover, the HTL-free perovskite solar cells on flexible PET substrates are first demonstrated, achieving a power conversion efficiency of 9.7%. The element distribution in the HTL-free perovskite solar cell was further investigated. The results indicated that the PbI 2 enriched near the PC 61 BM side for chlorobenzene treatment via the fast deposition crystallization method. Without using HTL on the ITO, the device is stable with comparison to that with poly(3,4-ethylenedioxylenethiophene): poly(styrene sulfonate) (PEDOT:PSS) as HTL. In addition, the fabricating time of the whole procedure from ITO substrate cleaning to device finishing fabrication only cost about 3 h for our mentioned devices, which is much more rapid than other structure devices containing other transporting layer. The high efficient and stable HTL-free CH 3 NH 3 PbI 3 /PC 61 BM planar heterojunction perovskite solar cells with the advantage of saving time and cost provide the potential for commercialization printing electronic devices. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PVSCs) are promising photovoltaic technologies for realizing power sources with outstanding power conversion efficiency (PCE) and low‐cost properties. However, the extraordinary photovoltaic performance can be maximized only if an extremely stabilized device structure is developed. Here, a novel glued poly(ethylene‐co‐vinyl acetate) (EVA) interfacial layer is introduced to fabricate highly efficient and stable PVSCs with excellent waterproofness and flexibility. This strategy can effectively passivate the perovskite surface, reduce defect density, and balance charge transfer, which leads to a champion PCE of 19.31% for a 0.1 cm2 device and 11.73% for a 25 cm2 solar module. More importantly, the formation of a glued EVA thin layer on the surface of perovskite can inhibit ionic migration to the Ag electrode, form favorable interfacial contact and adhesive interaction with the perovskite/[6,6]‐phenyl‐C61‐butyric acid methyl ester to sustain mechanical bending, and produce significant waterproofness from moisture invasion, thus facilitating improvement in the operational stability of the PVSCs. The EVA‐treated PVSCs exhibit superior PCE values of 15.12% for a flexible device (0.1 cm2) and 8.95% for a flexible module (25 cm2), as well as over 85% retention after 5000 bending cycles, which opens up a new strategy for the practical application of PVSCs in portable and wearable electronics. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: competitive growth; micro-contact print; perovskites; solar cells; surface wettability In article number 1900838, Mingzhu Li, Yanlin Song and co-workers report a competitive perovskite grain growth approach via a micro-contact print (MicroCP) method with CD discs as templates for printing a wettability-patterned substrate, to achieve a large-grained perovskite and avoid discontinuous perovskite films caused by the low wettability of substrates, resulting in efficiencies over 20% for the MicroCP perovskite solar cells. Competitive growth, micro-contact print, perovskites, solar cells, surface wettability.

Novel photovoltaic perovskite solar cells (PSCs) with high‐efficient photovoltaic property are largely in thrall to the uncertain perovskite grain size and inevitable defects. Here, inspired by the competitive growth between tree and grass in the forest system, a competitive perovskite grain growth approach via micro‐contact print (MicroCP) method (CD disk as templates) for printing wettability‐patterned substrate is proposed, aiming to achieve large‐grained perovskite and avoid discontinuous perovskite films caused by the low wettability of substrates. A MicroCP process is employed to construct a patterned wettability surface for the perovskite competitive growth mechanism on the electrode surface. This approach modifies the substrates quickly, ensures the uniform coverage of perovskite due to the function of ‐NH2 and Pb2+ bonds, and converts the perovskite films composed of small grains and pinholes into high‐quality perovskite films, free from pinholes and made up of large grains, resulting in efficiencies over 20% for the MicroCP PSCs. [ABSTRACT FROM AUTHOR]

The notoriously poor stability of perovskite solar cells is a crucial issue restricting commercial applications. Here, a fluorinated perylenediimide (F‐PDI) is first introduced into perovskite film to enhance the device's photovoltaic performance, as well as thermal and moisture stability simultaneously. The conductive F‐PDI molecules filling at grain boundaries (GBs) and surface of perovskite film can passivate defects and promote charge transport through GBs due to the chelation between carbonyl of F‐PDI and noncoordinating lead. Furthermore, an effective multiple hydrophobic structure is formed to protect perovskite film from moisture erosion. As a result, the F‐PDI‐incorporated devices based on MAPbI3 and Cs0.05 (FA0.83MA0.17)0.95 Pb (Br0.17I0.83)3 absorber achieve champion efficiencies of 18.28% and 19.26%, respectively. Over 80% of the initial efficiency is maintained after exposure in air for 30 days with a relative humidity (RH) of 50%. In addition, the strong hydrogen bonding of F···H‐N can immobilize methylamine ion (MA+) and thus enhances the thermal stability of device, remaining nearly 70% of the initial value after thermal treatment (100 °C) for 24 h at 50% RH condition. [ABSTRACT FROM AUTHOR]

High electronic quality perovskite films with a balanced charge transportation is critical for satisfying high‐performance for perovskite solar cells (PVSCs). However, the inferior band alignment of tin‐based perovskite films with an adjacent hole‐transport layer (HTL) leads to a poor hole transportation and collection. In this work, the semiconducting molecule poly[tetraphenylethene 3,3′‐(((2,2‐diphenylethene‐1,1‐diyl)bis(4,1‐phenylene))bis(oxy))bis(N,N‐dimethylpropan‐1‐amine)tetraphenylethene] (PTN‐Br) is introduced into a lead‐free perovskite precursor to form a bulk heterojunction film. In addition, the PTN‐Br molecule with the suitable highest occupied molecular orbital energy level (−5.41 eV) can fill into the grain boundaries of the perovskite film, serving as a hole‐transport medium between grains. The gradient band alignment of the perovskite film with poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL ensures excellent hole transportation and higher open‐circuit voltage. In addition, the π‐conjugated polymer PTN‐Br can passivate trap states within the perovskite film due to the formation of Lewis adducts between uncoordinated Sn atoms and the dimethylamino of PTN‐Br. Consequently, a champion efficiency of 7.94% is achieved with significant enhancements in the open‐circuit voltage and fill factor. Furthermore, the PTN‐Br incorporated device shows better ultra violet (UV) stability because of the UV barrier and passivating effect of PTN‐Br, retaining about 66% of its initial efficiency after 5 h of continuous UV light irradiation. [ABSTRACT FROM AUTHOR]

A highly flexible perovskite film prepared by incorporating elastomer polyurethane (PU) is described by Licheng Tan, Yiwang Chen, and co‐workers in article number 1703061. By cross‐linking the grain boundaries between neighboring perovskite crystals, a PU network is formed to significantly improve the bendability of perovskite films. This strategy is expected to be of profound significance for the realization of perovskite solar cells as flexible and wearable devices. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The preparation of perovskite solar cells (PSCs) in the air environment has attracted the attention of numerous experimenters due to its low preparation cost and the possibility of commercialization. Although the power conversion efficiency (PCE) of PSCs has increased rapidly and exceeded 25%, which is comparable to commercial polysilicon solar cells, most certified or reported high‐efficiency perovskite solar cells are still confined to glove boxes or relatively small active areas in the air environment due to moisture, oxygen, high temperature, and ultraviolet (UV) factors. In this review, the factors that lead to perovskite degradation are reviewed, and the appropriate strategies for manufacturing high‐efficiency and stable perovskite solar cells under environmental conditions are summarized to help the technology be commercialized for high‐quality, stable, and large‐area perovskite thin films in the air. [ABSTRACT FROM AUTHOR]

Abstract Perovskite solar cells are promising photovoltaic devices with high efficiency beyond 23%, but thermal instability is one of the key obstacles for the commercialization. To prolong thermal stability, (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl) phenyl)dimethylamine is doped into a state-of-the-art fullerene derivative with a hydrophilic triethylene glycol type side chain as electron transport layer in planar perovskite cells with low-temperature process (<100 °C). The addition of dopant in electron transport layer results in stable layered structure. We observe that the increase of electron transport layer conductivity and optimized reduction of work function facilitate charge extraction and improve the energy level alignment. As a result, CH 3 NH 3 PbI 3 -based n-i-p perovskite cells with doped electron transport layer exhibit a hysteresis-free power conversion efficiency of 18.5%, outperforming the ones based on pristine electron transport layer (16.2%) or the other fullerene derivatives. Strikingly, the corresponding unsealed devices in air show long-term thermal stability. Devices sustain 85% of their initial efficiency after 1000 h storage under 60 °C. Our work bodes well for the dawn of commercialization of perovskite devices, providing the chance for the exploration of such high-efficiency devices with long-term thermal stability on flexible substrates. Graphical abstract Image 1 Highlights • Deposited doped PTEG-1 is not required thermally annealing. • The doped PTEG-1 self-assembled into stable layered structure. • CH 3 NH 3 PbI 3 -based n-i-p cells exhibit a PCE of 18.5%. • Devices sustain 85% of initial efficiency after 1000 h under 60 °C. [ABSTRACT FROM AUTHOR]

Pure chlorobenzene (CBZ) and 2-propanol (IPA) or mixed-solvent assisted spin-coating have been applied to one-step fabricate CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3−x Cl x perovskite films, respectively. However, with the treatment of pure- or mixed solvent, there are obvious differences in the formation of CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3−x Cl x perovskite films with full coverage and large crystal grain size, as well as the role in the photovoltaic performance. Furthermore, the nucleation and growth dynamics of perovskite crystals have been taken into consideration with the activation energy of transporting crystallizing segments across the crystal interface and the formation free energy of a critical-sized nucleus. Planar heterojunction (PHJ) perovskite solar cells (PSCs) based on CH 3 NH 3 PbI 3 by mixed-solvent treatment exhibit a poor power conversion efficiency (PCE) owing to the formation little amount of perovskite crystals with low crystallinity. While pure CBZ treatment renders the corresponding device get efficiency of 8.1%, which is due to the formation of uniform CH 3 NH 3 PbI 3 thin film with higher surface coverage and crystallinity. Inversely, PSCs based on CH 3 NH 3 PbI 3−x Cl x with mixed-solvent shows the highest PCE of 9.2%, short-circuit current density ( J sc ) of 16.06 mA/cm 2 and fill factor (FF) of 63.6% with high device reproducibility and low photocurrent hysteresis, because of possessing higher light absorption ascribed from bigger crystal size and better surface morphology with no pin-holes. These results will provide significant guidance for CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3−x Cl x perovskite device performance optimization and large-scale application by pure- and mixed-solvent treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • The chelation between PDA and metal ions can efficiently passivate the surface defect of AZO. • AZO:PDA can induce the vertical growth of perovskite and release the lattice strain. • The incorporation of PDA restrains interfacial deprotonation reaction between AZO and perovskite. • The rigid and flexible AZO:PDA based PVSCs exhibits excellent PCEs of 21.36% and 18.51%. • The unencapsulated device shows excellent photostability and thermostability. Zinc oxide (ZnO) is expected to be the desirable electron transport layer (ETL) for planar perovskite solar cells (PVSCs) because of excellent electron mobility, superior transmittance in the visible spectrum and aligned energy level with perovskite. However, the development of ZnO-based PVSCs is relatively stagnant, mainly due to interfacial mismatch and deprotonation. Herein, aluminium-doped ZnO modified by polydopamine (AZO:PDA) as ETL has firstly been found to optimize interfacial contact and inhibit detrimental interfacial reaction. The surface defects of AZO:PDA has been effectively passivated to mitigate the non-radiative carriers recombination. Moreover, various functional hydroxyl and amino groups from AZO:PDA can not only induce the vertical growth of perovskite grains, but also release the lattice strain and inhibit the deprotonation reaction. Consequently, the rigid device (ITO/AZO:PDA/FA 0.9 Cs 0.1 PbI 3 /Spiro-OMeTAD/Ag) shows a champion power conversion efficiency (PCE) of 21.36% with small hysteresis effect. The unencapsulated devices can preserve 90% and 88% of their initial efficiencies after storing at 85 °C for 360 h and continuous light for 500 h, respectively. In addition, a PCE of 18.51% is achieved in flexible device due to the advantages of bendability and interfacial adhesion from AZO:PDA, which is one of the highest PCEs recorded among ZnO-based flexible PVSCs. [ABSTRACT FROM AUTHOR]