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Deposition of a passivation layer on top of the perovskite is proven to be an effective method for improving the efficiency and long‐term stability of perovskite solar cells (PSCs). And the spin‐coating method is the most typical and popular method developed for this purpose. However, the spin‐coating method wastes substantial passivator materials, thus the quantitative relationship between the passivator amount and the device performance cannot be obtained. Herein, a quantitative deposition method is developed through drop‐on‐demand inkjet printing to investigate the influence of 2‐adamantylamine hydrochloride (2‐ADAHCl) deposition surface density on the device performance, which is found to have a significant impact on the device performance. A low deposition surface density of 1.1 µg cm−2 does not reach its optimum passivation capability. In contrast, an excess deposition surface density of 10.1 µg cm−2 would lead to energy level mismatch and large series resistance at the perovskite/hole transport layer (HTL) interface, thus resulting in inferior device properties. At an optimum deposition surface density of 2.5 µg cm−2, perovskite surface defects are greatly suppressed, and the interfacial contact between perovskite and HTL is improved. Finally, PSCs with a high efficiency of 24.57% are achieved with improved operational and environmental stabilities. [ABSTRACT FROM AUTHOR]

Perovskite films prepared by the solution process usually result in irregular grain orientation and rich buried interface defects, hindering the further improvement of device performance. Herein, multi‐fluorine‐containing C60‐ and C70 (higher fullerene)‐porphyrin derivatives, F60PD and F70PD, are synthesized and pre‐buried to modify the SnO2/perovskite heterointerface. The F70PD modification layer provides a better perovskite quality and more effective electron transporting capability compared to the corresponding F60PD, with the F70PD being more effective in regulating the perovskite growth, passivating the buried interface defects, and optimizing the interface energy level alignment. Consequently, the F70PD‐based device delivers superior efficiency and stability than the control and F60PD‐based devices. The F70PD‐based device yields a champion efficiency of 24.09% with negligible hysteresis. Meanwhile, due to the increased activation energy of ion migration, the F70PD‐based device maintains 80% of its initial efficiency after operating at the maximum power point for 1620 h. This study highlights the potential of designing higher fullerene materials for buried interface to further improve the perovskite solar cells' performance. [ABSTRACT FROM AUTHOR]

The non‐radiative recombination at the interfaces of perovskite solar cells (PSCs) is a crucial issue that limits the efficiency and stability of the devices. State‐of‐the‐art surface passivation strategies usually utilize alkyl ammonium halides to suppress the non‐radiative recombination of PSCs, but their high surface reactivity leads to the transformation into 2D perovskites under working conditions, limiting the passivation effect and the charge transport of PSCs. Herein, a non‐halide ionic salt 1‐naphthylmethylammonium formate (NMACOOH) is synthesized for surface passivation of perovskite films. In contrast to the traditional 1‐naphthylmethylammonium iodide, NMACOOH treatment hinders the formation of 2D perovskite and forms a thermally stable PbI2‐NMACOOH adduct on the perovskite surface. Surface characterization reveals that NMA+ can passivate the cation vacancies of the 3D perovskite while HCOO− passivates the metallic Pb0 and halide‐vacancy defects. Therefore, the non‐radiative recombination of PSCs is dramatically suppressed and a high open‐circuit voltage of 1.19 V is obtained. Finally, PSCs with high efficiency of 24.75% and improved long‐term stability (98% of the initial efficiency after 1800‐h storage) are obtained. Moreover, the NMACOOH‐passivated devices also show robust operational stability, retaining 83% of the initial efficiency after working for 658 h under continuous one‐sun illumination. [ABSTRACT FROM AUTHOR]

Interfacial defects are one of the main origins of the hysteresis effect and limit the efficiency and light stability of perovskite solar cells (PSCs). Herein, the authors propose to grant the hole‐transport materials' (HTMs) improved isotropic coordination and defect passivation through simple halogenation, enabling a robust perovskite/hole‐transport layer interface while avoiding the use of an external passivation layer. First‐principles simulations and experimental results show that the halogenated HTMs offer more isotropic coordination sites for Pb2+ ions than the halogen‐free ones, thus providing the enhanced passivating ability of defects regardless of their molecular orientation at the surface of perovskite films. Consequently, the PSCs based on the chlorinated spiro[fluorene‐9,9′‐xanthene]‐based HTM show suppressed nonradiative recombination, delivering a remarkable open‐circuit voltage (VOC) enhancement (from 1.07 to 1.14 V) and a minimal hysteresis index of as low as 0.07%. The corresponding cells also show much improved light stability, retaining 81% of the initial efficiency after 1000 h of continuous illumination at the maximum power point. This work demonstrates that a solid isotropic coordination capability of HTMs with Pb2+ is critical to forming a robust interface and improving the PSCs' light stability. [ABSTRACT FROM AUTHOR]

The under‐coordinated defects within perovskite and its relevant interfaces always attract and trap the free carriers via the electrostatic force, significantly limiting the charge extraction efficiency and the intrinsic stability of perovskite solar cells (PSCs). Herein, self‐diffusion interfacial doping by using ionic potassium L‐aspartate (PL‐A) is first reported to restrain the carrier trap induced recombination via the reconstruction of energy level structure at SnO2/perovskite interface in conventional n‐i‐p structured PSCs. Experiments and theories are consistent with the PL‐A anions that can remain at the SnO2 surface due to strong chemical adsorption. During the spin‐coating of the perovskite film, the cations gradually diffuse into perovskite and endow an n‐doping effect, which provides higher force and a better energy level alignment for the carrier transport. As a result, they obtained 23.74% power conversion efficiency for the PL‐A modified small‐area devices, with dramatically improved open‐circuit voltage of 1.19 V. The corresponding large‐area devices (1.05 cm2) achieved an efficiency of 22.23%. Furthermore, the modified devices exhibited negligible hysteresis and enhanced ambient air stability exceeding 1500 h. [ABSTRACT FROM AUTHOR]

To date, organic–inorganic hybrid perovskite solar cells (PSCs) have reached a certified efficiency of 25.7%, showing great potential in upscale industrial commercialization. However, a huge obstacle facing the industrialization of PSCs is the decreased efficiency and long‐term stability when upscaling the device area. To overcome these issues, blade‐coating methods have been developed to fabricate large‐area PSCs due to their capability to deposit uniform large‐area perovskite films. Ink engineering plays an important role in the blade‐coating, especially for crystallinity and defect control. In this review, the blade‐coating method to fabricate large‐area perovskite films is first introduced. Then, the perovskite ink engineering for blade‐coating PSCs is systematically summarized. Specifically, the effects of perovskite composition management and solvent engineering on perovskite film quality are discussed, and recent efforts in additive strategy to passivate perovskite defects are also summarized. Subsequently, recent advances in functional layer ink engineering and fully blade‐coated PSCs are summarized. Moreover, the applications of blade‐coating method in hole transporting material‐free carbon‐based PSCs are discussed. Finally, some suggestions and an outlook on this field are provided to help facilitate highly efficient and stable blade‐coated PSCs. [ABSTRACT FROM AUTHOR]

Designing functional fullerenes with roles beyond defect passivation and electron‐transporting for perovskite solar cells (PSCs) is essential to the development of fullerenes and PSCs. Here, the authors design and synthesize a functional fullerene, FPD, composed of a C60 cage, a porphyrin ring, and three pentafluorophenyl groups. The structure features of FPD enable it can form chemical interactions with the perovskite lattices. These interactions enhance the defect passivation effect and prevent the decomposition of perovskite under irradiation. As a result, the FPD‐based device yields an improved power conversion efficiency of 23% with substantially enhanced operational stability (T80 > 1500 h). Furthermore, once got damaged, the FPD can prevent lead leakage by forming a stable and water‐insoluble complex (FPD‐Pb). Their findings provide a novel strategy to achieve high‐performance and eco‐friendly PSCs with functional fullerene materials. [ABSTRACT FROM AUTHOR]

Solution‐processed metal halide perovskites have the advantages of a tunable bandgap, excellent charge transport properties, and suitable exciton binding energy. They therefore emerge as promising semiconductors for efficient perovskite solar cells (PSCs) and bright perovskite light‐emitting diodes (PLEDs). In addition, these devices possess a similar planar–heterojunction architecture, thus novel dual‐functional perovskite light‐emitting solar cells (PLESCs) that can realize electrical‐to‐optical and optical‐to‐electrical conversion on one device are developed. To date, high‐performance PLESCs with 17.2% electroluminescence external quantum efficiency and 25.2% power conversion efficiency are achieved using a holistic optimization approach. However, a comprehensive review focusing on dual‐functional PLESCs with discussion on their development and limitations, remains lacking. Herein, the rapid progress in PLESCs, including 0D quantum dot, 2D Ruddlesden–Popper, and 3D bulk perovskite devices, is reviewed. First, the fundamental understanding of the device structure and working principle of PLESCs is overviewed. Second, the state‐of‐the‐art developments for simultaneously achieving high‐efficiency PSCs and PLEDs, focusing on defect passivation, interface optimization, energy level alignment, and dimensional control, are comprehensively summarized. Finally, the authors offer some perspectives for future trends in the development of promising PLESCs, which can provide guidelines for this emerging field. [ABSTRACT FROM AUTHOR]

It is challenging to passivate defects that are buried in the depth of perovskite films; most of the reported passivation methods cannot reach the deep defects. Herein, methanol is adopted as a dual‐functional reagent to not only act as a solvent but also help the dissolved ions penetrate the depth of perovskite films. By treating the as‐prepared perovskite films with CsBr/methanol solution, Br− ions can react with the undercoordinated Pb2+, and Cs+ ions can fill in the cation vacancies. This strategy enables surface and bulk defects passivation to be achieved simultaneously. The nonradiative recombination of the double‐passivated devices is significantly suppressed and the migration of charged defects is remarkably hindered. As a result, an improved power conversion efficiency of 19.5% and an open‐circuit voltage of 1.183 V is achieved. Moreover, the passivated device can retain ≈80% of the initial efficiency after working for 500 h at maximum power point under 1‐sun illumination, whereas the pristine device reaches 80% of the initial efficiency after only 90 h. This work demonstrates that surface and bulk defects passivation is critical to improve the efficiency and long‐term operational stability of the perovskite solar cells. [ABSTRACT FROM AUTHOR]

Fullerene derivatives, especially after purposely functionalization, have potential to efficiently passivate interfacial defects between perovskites and electron transport layers. In this work, a fullerene derivative with amine functional group, 2,5‐diphenyl C60 fulleropyrrolidine (DPC60), is synthesized and employed as an interfacial layer between a perovskite and SnO2 in planar perovskite solar cells (PSCs). The cis‐configuration and the specific amine group of DPC60 effectively enhance the chemical interaction between the perovskite and DPC60, promoting the passivation of perovskite defects at the interface. The suitable energy level of DPC60 and the improved conductivity of the SnO2/DPC60 film facilitate the electron extraction from the perovskite layer. As a result, PSCs incorporated with DPC60 reach a PCE of 20.4% with high reproducibility, which is much higher than that of the bare SnO2 based devices (18.8%). Furthermore, the hydrophobic DPC60 layer suppresses heterogeneous nucleation and improves the crystallinity of the perovskite film, resulting in better device stability, retaining 82% of its initial efficiency after 200 h of 1 sun continuous irradiation and thermal ageing (55 ± 5 °C). [ABSTRACT FROM AUTHOR]

Carbon-based hole transport material (HTM)-free perovskite solar cells (PSCs) have shown much promise for practical applications because of their high stability and low cost. However, the efficiencies of this kind of PSCs are still relatively low, especially for the simplest paintable carbon-based PSCs, in comparison with the organic HTM-based PSCs. This can be imputed to the perovskite deposition methods that are not very suitable for this kind of devices. A solvent engineering strategy based on two-step sequential method is exploited to prepare a high-quality perovskite layer for the paintable carbon-based PSCs in which the solvent for CH3NH3I (MAI) solution at the second step is changed from isopropanol (IPA) to a mixed solvent of IPA/Cyclohexane (CYHEX). This mixed solvent not only accelerates the conversion of PbI2 to CH3NH3PbI3 but also suppresses the Ostwald ripening process resulting in a high-quality perovskite layer, e.g., pure phase, even surface, and compact capping layer. The paintable carbon-based PSCs fabricated from IPA/CYHEX solvent exhibits a considerable enhancement in photovoltaic performance and performance reproducibility in comparison with that from pure IPA, especially on fill factor (FF), owing mainly to the better contact of perovskite/carbon interface, lower trap density in perovskite, higher light absorption ability, and faster charge transport of perovskite layer. As a result, the highest power conversion efficiency (PCE) of 14.38% is obtained, which is a record value for carbon-based HTM-free PSCs. Furthermore, a PCE of as high as 10% is achieved for the large area device (1 cm2), also the highest of its kind. [ABSTRACT FROM AUTHOR]

Hybrid organic/inorganic perovskite solar cells (PSCs) have emerged as a highly promising alternative renewable energy source because of their high efficiency and low-cost solution processable manufacturing technology. However, the commonly used spin coating process limits the large-scale manufacturing of perovskite layers for commercialization. Here we report on the development of an electrodeposition technique for fabricating perovskite layers and demonstrate its simplicity, versatility, scalability and roll-to-roll manufacturing compatibility. The key step is the electrodeposition of a PbO 2 layer on TiO 2 scaffold, which is then subjected to chemical bath conversion to sequentially generate PbI 2 and CH 3 NH 3 PbI 3 perovskite. Clearly demonstrated is the controllability of morphology and optical properties of the CH 3 NH 3 PbI 3 layer, leading to a higher power conversion efficiency (PCE) reproducibility and a higher average PCE when incorporated into carbon-based PSCs than with the spin coating technique. Remarkably, the cell area of electrodeposited PSCs could be easily scaled up to 4 cm 2 with an excellent perovskite film uniformity, rendering a PCE gain of 36.3% over the spin-coated counterpart. We further demonstrate the deposition of perovskite layers on complex shape substrates (e.g., stainless steel net), which would be rather difficult or impossible with other competing film deposition techniques. These results establish electrodeposition as a versatile and controllable route toward low-cost and large scalable manufacturing of high efficiency PSCs. [ABSTRACT FROM AUTHOR]

We systematically review the progress of CsPb(I x Br 1− x) 3 solar cells in four aspects: phase stability, crystallization control, low-temperature preparation, and defect passivation. We propose challenges and future directions for developing highly efficient and stable devices. Owing to its nice performance, low cost, and simple solution-processing, organic-inorganic hybrid perovskite solar cell (PSC) becomes a promising candidate for next-generation high-efficiency solar cells. The power conversion efficiency (PCE) has boosted from 3.8% to 25.2% over the past ten years. Despite the rapid progress in PCE, the device stability is a key issue that impedes the commercialization of PSCs. Recently, all-inorganic cesium lead halide perovskites have attracted much attention due to their better stability compared with their organic-inorganic counterpart. In this progress report, we summarize the properties of CsPb(I x Br 1− x) 3 and their applications in solar cells. The current challenges and corresponding solutions are discussed. Finally, we share our perspectives on CsPb(I x Br 1− x) 3 solar cells and outline possible directions to further improve the device performance. [ABSTRACT FROM AUTHOR]