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We demonstrate an inclusive study on the growth, properties and application in solar cells of FA-based Ruddlesden–Popper type perovskites M2FAn−1PbnI3n+1 (M = benzylamine (PMA) or FA) fabricated via two-step sequential deposition.

Metal oxides are commonly employed as electron transport layers (ETLs) for n-i-p perovskite solar cells (PSCs), but the presence of surface traps and their mismatched energy alignment with perovskites limits the corresponding device performance. Therefore, the interfacial modification of ETLs by functional molecules becomes an important strategy for tailoring the interfacial properties and facilitating an efficient charge extraction and transport in PSCs. However, an in-depth understanding of the influences of their molecular structures on the surface chemistry and electronic properties of ETLs is rarely discussed. Herein, three carboxylic acid-based molecules with different chemical structures were employed to modify the SnO

Summary Two-dimensional (2D) perovskites with excellent stability and optoelectronic properties have aroused great interest for use in perovskite solar cells (PSCs). To date, the power conversion efficiencies (PCEs) of state-of-the art 2D-PSCs are non-satisfactory because of higher recombination losses in 2D quantum wells. Here, based on a series of alkylic ammonium spacers (ethylamine to hexylamine) with different chain lengths, we present a strategy via the molecular van der Waals interaction to realize modified crystallization, phase distribution, and quantum-confined behaviors in Ruddlesden-Popper 2D perovskites (n = 4). With the optimal amylamine (AA) spacer, high-quality 2D perovskites featuring well-aligned phase alignments with fewer unfavorable n-value species and a reduced exciton binding energy have been realized, leading to sufficient charge transfers through different n-value components. The devices based on (AA)2MA3Pb4I13 yield a champion PCE of 18.42%, showing an impressive open-circuit voltage of 1.25 V and a fill factor exceeding 0.80.

X-ray detectors have broad applications in medicine and industry. Although flexible lead-free perovskite films are competitive because of their lightweight and low toxicity, they are less efficient due to low charge transport. Herein, we report low-toxicity, flexible X-ray detectors based on p-type doped MA

Even though the perovskite solar cell (PSC) has been so popular for its skyrocketing power conversion efficiency (PCE), its further development is still roadblocked by its overall performance, in particular long-term stability, large-area fabrication and stable module efficiency. In essence, the soft component and ionic–electronic nature of metal halide perovskites usually chaperonage large number of anion vacancy defects that act as recombination centers to decrease both the photovoltaic efficiency and operational stability. Herein, we report a one-stone-for-many-birds strategy in which both anion-fixation and associated undercoordinated-Pb passivation are achieved by using a single amidino-based ligand, namely 3-amidinopyridine (3AP), for metal-halide perovskite to overcome above challenges. The resultant devices attain a power conversion efficiency as high as 25.3% (certified at 24.8%) with substantially improved stability. Moreover, the device without encapsulation retained 92% of its initial efficiency after 5000 h exposure in ambient and 90% of its initial efficiency after 200 h of operation at the maximum power point under simulated AM1.5G illumination. It is expected this one-stone-for-many-birds strategy will benefit large-area fabrication that desires for simplicity.

Solution-processed perovskite solar cells (PSCs) have made great progress in past years. However, most fabrication methods of PSCs in the lab cannot be directly transferred to industrial printing, and the toxic volatile processing solvents are hazardous to human health and environment. Here, we demonstrate ambient green-solvent printing for high-performance methylammonium lead iodide-based perovskite solar cells enabled by a well-regulated microstructure and lattice strain in a printed perovskite layer. A smooth and uniform perovskite layer can be obtained from green solvents via controlling the wetting and spreading of viscous perovskite precursor ink on the hot substrate. The residual lattice strain in the hot-printed perovskite layer was effectively decreased with addition of methylammonium bromide additive, which also largely increased the perovskite grain size. This morphological improvement contributes to decreased defect density, improved charge transport and suppressed charge recombination. As a result, the solar cell based on ambient green-solvent printed key layers achieves an efficiency as high as 20.21% (average efficiency of 19.27%). The demonstration of ambient green printing and lattice strain control for high-quality printed layer paves the way towards the future commercialization of PSCs.

New structural type of 2D AA′ n −1M n X3 n +1 type halide perovskites stabilized by symmetric diammonium cations has attracted research attention recently due to the short interlayer distance and better charge‐transport for high‐performance solar cells (PSCs). However, the distribution control of quantum wells (QWs) and its influence on optoelectronic properties are largely underexplored. Here effective phase‐alignment is reported through dynamical control of film formation to improve charge transfer between quantum wells (QWs) for 2D perovskite (BDA)(MA) n ‐1Pb n I3 n +1 (BDA = 1,4‐butanediamine, 〈n〉 = 4) film. The in situ optical spectra reveal a significantly prolonged crystallization window during the perovskite deposition via additive strategy. It is found that finer thickness gradient by n values in the direction orthogonal to the substrate leads to more efficient charge transport between QWs and suppressed charge recombination in the additive‐treated film. As a result, a power conversion efficiency of 14.4% is achieved, which is not only 21% higher than the control one without additive treatment, but also one of the high efficiencies of the low‐n (n ≤ 4) AA′ n −1M n X3 n +1 PSCs. Furthermore, the bare device retains 92% of its initial PCE without any encapsulation after ambient exposure for 1200 h., The in situ optical spectra reveal a significantly prolonged crystallization window during the perovskite deposition via additive strategy. Finer thickness gradient by n values in the direction orthogonal to the substrate leads to more efficient charge transport between quantum wells and suppressed charge recombination in the additive‐treated film. Finally, the power conversion efficiency of 14.4% is obtained.

Eco-friendly printing is important for mass manufacturing of thin-film photovoltaic (PV) devices to preserve human safety and the environment and to reduce energy consumption and capital expense. However, it is challenging for perovskite PVs due to the lack of eco-friendly solvents for ambient fast printing. In this study, we demonstrate for the first time an eco-friendly printing concept for high-performance perovskite solar cells. Both the perovskite and charge transport layers were fabricated from eco-friendly solvents via scalable fast blade coating under ambient conditions. The perovskite dynamic crystallization during blade coating investigated using in situ grazing incidence wide-angle X-ray scattering (GIWAXS) reveals a long sol-gel window prior to phase transformation and a strong interaction between the precursors and the eco-friendly solvents. The insights enable the achievement of high quality coatings for both the perovskite and charge transport layers by controlling film formation during scalable coating. The excellent optoelectronic properties of these coatings translate to a power conversion efficiency of 18.26% for eco-friendly printed solar cells, which is on par with the conventional devices fabricated via spin coating from toxic solvents under inert atmosphere. The eco-friendly printing paradigm presented in this work paves the way for future green and high-throughput fabrication on an industrial scale for perovskite PVs.

Correction for ‘Formamidinium-based Ruddlesden–Popper perovskite films fabricated via two-step sequential deposition: quantum well formation, physical properties and film-based solar cells’ by Jing Lu et al., Energy Environ. Sci., 2022, 15, 1144–1155, DOI: 10.1039/D1EE02851K.

This work was supported by the King Abdullah University of Science and Technology (KAUST), National Natural Science Foundation of China (61604092), and the National Natural Science Foundation of China (61974085). CHESS was supported by the NSF & NIH/NIGMS via NSF award DMR-1332208. All the commercial instruments and materials mentioned here are identified to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.