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The loss of organic components from perovskites has inevitably triggered a series of undesirable results, including ion migration, increased defects, and organic vapors, which severely limit the performance of perovskite solar cells (PSCs) and impede their progress toward commercial applications. To circumvent this issue, we report a novel covalent bonding strategy by employing bis-diazirine (BD) molecules to covalently bond organic cations of perovskites. Experimental and ab initiosimulation results confirmed the efficacy of BD molecules to strongly immobilize the organic cations and eventually enhance the thermal, illumination, and electrical bias resistance properties of perovskites. Consequently, highly efficient (24.36% efficiency, certified 24.02%) and ultra-stable PSCs were realized, which retained 98.6% of their initial efficiency even after 1,000 h of operational tests.

The 2D/3D heterojunction structure emerges as a viable approach for enhancing the efficiency and stability of perovskite photovoltaics. However, the formation of an accumulative low-dimensional 2D perovskite (n=1) cladding layer often impedes carrier transport due to the insulating nature and high quantum confinement, and there is a paucity of detailed understanding regarding its surface phase control. This study introduces a Dion-Jacobson (DJ) phase 2D perovskite, employing decane-1,10-diammonium diiodide (DDADI) to interface with 3D perovskite, leveraging long-chain diammonium cations for structural stability and defect passivation on the 3D FAPbI3perovskite surface. In addition, a novel PbI2-assisted phase control (PAPC) technique is proposed to mitigate the quantum confinement effects of the 2D layer, especially reducing the formation of the highly confined insulating n=1 phase. X-ray scattering analysis confirms the method's efficacy in promoting the formation of an n=2 phase, facilitating cascading HOMO levels and improving hole carrier transport. The optimized 2D/3D perovskite solar cell (PSC) achieve an exemplary efficiency of 25.16 %, with a notable open-circuit voltage of 1.192 V, and retain 92.9 % of its initial efficiency after 1000 hours in a nitrogen atmosphere, signifying a strategic advancement in 2D/3D PSC construction.

These days, organic–inorganic hybrid perovskites (OIHP) and non-fullerene acceptor (NFA) molecules are all at the frontiers of research and development in the domain of photovoltaics. A careful design and use of inorganic transparent metal oxides with wide band gaps as electron and hole transport layers are critically important for highly efficient and stable solar cells. As one of the most favorable electron transport materials, tin oxide (SnO2), which has been frequently utilized in highly efficient OIHP solar cells, is rarely seen in the application of NFA organic bulk heterojunction (BHJ) solar cells. To appropriately tailor an interface of SnO2and an organic blend, while to make them compatible and useful may offer some opportunities for achieving higher efficiencies and longer lifetimes. In fact, there is still a lack of a method to solve the problem. Herein, a unique way is developed by implementing a surface decoration nanostructure such as low dimensional MAPbI3perovskite nanowires (PeNWs) at the interface of SnO2and the organic blend such as PBDB-T-SF:IT-4F. Such an interface functions well for the improvement of photovoltaic performance for the organic solar cell of the structure ITO(glass)/SnO2/PeNWs/PBDB-T-SF:IT-4F/MoO3/Ag. Experimental results indicate that the electron–hole dissociation, charge extraction, and photo-absorption ability of the organic solar cell can be improved significantly. The inside generation of the photocurrent is explored by the magneto-photocurrent method. Finally, the solar cell exhibits more than 80% power conversion efficiencies even after 20 days, which suggests the merits of having both SnO2and PeNWs in the NFA-based organic solar cell.

In this work, Al2O3–MnO2@diatomite composite (AM-Dt) was prepared by a simple hydrothermal method. This composite was formed by using diatomite as a porous substrate to support Al2O3and MnO2nanoparticles. It exhibited hierarchically porous structures and a high specific surface area (352 m2/g). The maximum phosphate adsorption capacity of AM-Dt was 63.7 mg of P/g of (Al2O3–MnO2), which is 6 times greater than those of Al2O3coated diatomite, Al2O3, and Al2O3–MnO2. The composite also showed superior adsorption efficiency, high structural stability, and selectivity for phosphate in the presence of interfering anions (Cl–, NO3–, and CO32–). With the help of X-ray photoelectron spectroscopy and P K-edge X-ray absorption near-edge structure analysis, it can be concluded that electrostatic attraction and formation of surface complexes via phosphate bonding with Al2O3and MnO2were the main adsorption mechanisms. The facile preparation method, excellent adsorption performance, and cost effectiveness suggested that this composite possesses a promising potential for phosphate removal from contaminated water.

Diatoms play an important role in the biogeochemical cycling of aluminum (Al) in oceans. This occurs via the uptake of biological Al (Albio), which is incorporated into the structure of diatom‐derived biogenic silica (DBSi) and the formation of adsorbed Al (Alads) on the DBSi surface of post‐mortem diatoms. Al occurrence influences DBSi dissolution and thus diatom‐driven carbon sequestration. However, the mechanism of Al occurrence in DBSi remains unclear. In this study, Albioand Aladsof DBSi from various diatom fossils in marine diatomaceous sediments were identified and quantified by combined focused ion beam thinning, elemental analysis, and the Al K‐edge X‐ray absorption near edge structure. Results showed the coexistence of Albioand Aladsin all diatomaceous sediments and Al‐bearing DBSi thus constitutes a biological Al pool. Albioand Aladswere mainly fourfold‐ and sixfold‐coordinated, respectively and Aladswas much more abundant than Albio. Moreover, even at low concentrations (with an Al/Si atomic ratio of 0.0031), Albiocan inhibit DBSi dissolution, effectively decreasing the extent of DBSi dissolution by ∼14%. Albioalso significantly increased the mechanical strength of DBSi. The average Young's modulus (a measure of the stiffness of a material) of cribrum layers in Al‐incorporated DBSi was ∼1.4 times higher than that of Al‐free DBSi. Our results further demonstrate that diatoms play a dominant role in the biogeochemical cycling of Al in oceans, and the Al of DBSi participates in diatom‐driven Si and C coupled cycles in oceans, influencing the effectiveness of diatom‐driven carbon export by regulating the dissolution and mechanical strength of DBSi. Diatoms contribute to oceanic carbon sequestration by exporting carbon from the ocean's surface to its depths. Aluminum (Al) is taken up by living diatoms to be incorporated into the structure of diatom‐derived biogenic silica (DBSi) (biogenic Al) and adsorbed by DBSi of post‐mortem diatoms (adsorbed Al). Al can inhibit the dissolution of DBSi and thus influence carbon sequestration. However, the mechanism of Al occurrence in DBSi remains unclear. Herein, we identified and quantified Al in DBSi from various diatom fossils using nano‐scaled microscopic analyses and investigated the influence of Al on DBSi properties. The results showed that biogenic Al and adsorbed Al have different coordination states in DBSi, and adsorbed Al was much more abundant than biogenic Al. The trace presence of biogenic Al effectively decreased the extent of DBSi dissolution by ∼14%. Moreover, biogenic Al influenced the properties of DBSi—the mechanical strength of Al‐incorporated DBSi was much higher than that of Al‐free DBSi. These results indicate that Al taken up by living diatoms noticeably influences the chemical and physical properties of diatom shells, which impacts the effectiveness of carbon export by diatoms. Coupled Si–Al biogeochemistry was revealed by investigating the occurrence of Al in diatom‐derived biogenic silica (DBSi)Nano‐scaled microscopic analyses were performed to identify and quantify Al in DBSi, which constitutes a biological Al poolAl effectively inhibits DBSi dissolution and significantly increases the mechanical strength of DBSi Coupled Si–Al biogeochemistry was revealed by investigating the occurrence of Al in diatom‐derived biogenic silica (DBSi) Nano‐scaled microscopic analyses were performed to identify and quantify Al in DBSi, which constitutes a biological Al pool Al effectively inhibits DBSi dissolution and significantly increases the mechanical strength of DBSi

The occurrence of minor elements in the structure of biogenic diatomaceous opal-A is an important issue because it is closely related to biogeochemical processes driven by the precipitation, sedimentation, and storage of diatoms, as well as to the properties and applications of diatomite, which is the sedimentary rock composed of diatomaceous opal-A. However, to date, there is no direct microscopic evidence for the existence of minor elements, such as Al, Fe, and Mg, in the structure of diatomaceous opal-A, because such evidence requires observation of the internal structure of frustules to exclude the disturbance of impurity minerals, which is technically challenging using conventional techniques. In this work, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) combined with energy-dispersive X‑ray spectroscopy (EDS) mapping analysis were performed on diatomaceous opal-A from three typical diatomite specimens that were pretreated using focused ion beam (FIB) thinning. This technique produces a slice of a diatom frustule for direct TEM observation of the internal structure of the diatomaceous opal-A. The results of this work clearly indicate that minor elements, such as Al, Fe, Ca, and Mg, conclusively exist within the siliceous framework of diatomaceous opal-A. The contents of these minor elements are at atomic ratio levels of 1 (minor element)/ 10 000 (Si) – 1/100, regardless of the genus of the diatoms. The occurrence of minor elements in the internal structure is likely through biological uptake during biosynthesis by living diatoms. Moreover, surface coatings composed of aluminosilicates on diatom frustules are common, and the contents of elements such as Al and Fe are tens or hundreds of times higher in the coatings than in the internal siliceous structure of diatomaceous opal-A. The discovery of the incorporation of the above-mentioned minor elements in the diatomaceous opal-A structure, both in the internal Si-O framework and on the surface, updates the knowledge about the properties of diatomite.

Polyethylene naphthalate (PEN) has been widely employed in highly desired flexible perovskite solar cells (F-PSCs) because of its better chemical stability and higher temperature tolerance. However, the naphthalene ring in the PEN induces poor transmittance in the ultraviolet (UV) region below 380nm, which significantly lowers the power conversion efficiency (PCE) of F-PSCs. Here, a novel strategy is adopted by introducing UV–visible downshifting material before the PEN substrate to increase the spectral response under the UV region. The PCE of modified F-PSCs increases from 22.19% to 22.81% and retains the same stability as that of the control device. The optimized device shows improved photocurrent due to the enhanced spectral response in the UV region. Interestingly, the humidity resistance characteristic of the device had also improved because of the hydrophobicity of downshifting materials. This novel strategy is distinguishable where downshifting material has been externally employed without altering the internal device architecture, which is also broadly applicable to other types of flexible solar cells.

Preferred crystalline orientation at the surface of quasi-2D organic–inorganic halide perovskites is crucial to promote vertical carrier transport and interface carrier extraction, which further contribute to device efficiency and stability in photovoltaic applications. However, loose unoriented and defective surfaces are inevitably formed in the crystallization process, especially with the introduction of bulky organic cations into the quasi-2D perovskites. Here, a facile and effective surface polishing method using a natural-friendly green solvent, 2,2,2-trifluoroethanol, is proposed to reconstruct the surface. After solvent polishing, the randomly oriented phases containing trap sites on the surface are successfully removed, and the compact vertical-oriented phases underneath are revealed with less defectiveness and better smoothness, which greatly facilitates carrier transport and interfacial charge extraction. Consequently, the green solvent polished devices show a boosting efficiency of 18.38% with a high open-circuit voltage of 1.21 V. The devices also show improved storage and operational stability.

It is essential to release annealing induced strain during the crystallization process to realize efficient and stable perovskite solar cells (PSCs), which does not seem achievable using the conventional annealing process. Here we report a novel and facile thermal gradient assisted crystallization strategy by simply introducing a slant angle between the preheated hot plate and the substrate. A distinct crystallization sequence resulted along the in-plane direction pointing from the hot side to the cool side, which effectively reduced the crystallization rate, controlled the perovskite grain growth, and released the in-plane tensile strain. Moreover, this strategy enabled uniform strain distribution in the vertical direction and assisted in reducing the defects and aligning the energy bands. The corresponding device demonstrated champion power conversion efficiencies (PCEs) of 23.70% and 21.04% on the rigid and flexible substrates, respectively. These highly stable rigid devices retained 97% of the initial PCE after 1097 h of storage and more than 80% of the initial PCE after 1000 h of continuous operation at the maximum power point. This novel strategy opens a simple and effective avenue to improve the quality of perovskite films and photovoltaic devices via strain modulation and defect passivation.