Organic small molecule electrodes with high-density redox sites are receiving attention for building high-capacity all-organic aqueous batteries. However, their poor charge transfer and high solubility stand as pivotal barriers for the full utilization of redox-active groups and the liberation of high theoretical capacity. Here we design a new-type nitroaromatic@MXene heterostructure by grafting four-electron-receptor 1,3,6,8-tetranitropyrene (TNP) molecule onto MXene scaffolds to construct a hybrid electrode (TNP@MXene) integrated with high activity, conductivity and structural stability. Four redox-active nitro motifs of TNP in TNP@MXene as H-bond acceptors are exclusively coordinated with flexible NH4 + charge carriers (H-bond donators) with lower activation energy (0.34 vs 0.48 eV for sole TNP molecule). Meanwhile, the highly conductive MXene provides continuous charge delocalization paths and strengthens anti-dissolution ability of TNP in aqueous electrolytes, enabling adequate exposure of nitro sites. Consequently, a two-step octa-H-bonded heterointerfacial NH4 + coordination mechanism is rationalized for TNP@MXene heterostructure electrode, affording an impressive capacity (342 mAh g-1). As a proof-of-concept, TNP@MXene as a cathode are further highlighted in aqueous NH4 +-ion battery, liberating superior energy density (182.3 Wh kg-1 cathode) and excellent lifespan (60 000 cycles). These findings constitute a major advancement of multielectron organic heterostructure materials as hybrid electrodes for advanced aqueous batteries.

Although surface passivation has significantly contributed to the rapid increase in the power conversion efficiency (PCE) of p-i-n perovskite solar cells (PSCs), the nonradiative recombination and energy level alignment at the perovskite/PCBM interface are still the key factors affecting the overall efficiency of p-i-n PSCs. Herein, a sequential interface engineering (SIE) strategy is developed to enhance charge transfer at the perovskite/PCBM interface in inverted p-i-n perovskite solar cells. p-Anisidine-2-sulfonic acid (pAsA) is used to passivate surface defects on the perovskite layer. Its multiactive-site binding aligns with the Pb2+ ion spacing on the perovskite surface. Then, vertically aligned ethylenediamine diiodide (EDAI2) is introduced into the perovskite/PCBM interface, forming dipoles to further passivate defects, reduce nonradiative recombination, and improve energy level alignment. The rationality of orthogonal bimolecular passivation is proven by theoretical calculations. The SIE strategy not only suppresses nonradiative recombination but also optimizes the surface morphology and energy level alignment at the interface. As a result, the MA-free inverted perovskite solar cells achieve a remarkable power conversion efficiency of 24.85%, and the stability is significantly enhanced by retaining 84.92% of the initial efficiency after 2000 h of MPP tracking under room-temperature conditions. The work underscores the potential of a synergistic passivation approach for advancing the performance and stability of PSCs.

Storing perovskite precursor solutions under ambient conditions poses a significant challenge to commercialization, as humidity and oxidation accelerate ageing and introduce defects in devices. A major contributor to solution ageing and impurity perovskite phases is the deprotonation of hybrid organic cations, specifically methylammonium (MA+) and formamidinium (FA+). In this work, a proton-rich additive, 4-(aminomethyl)pyridine 2-iodide, is used to inhibit MA+ deprotonation in precursor solutions by generating free H+, thereby mitigating the degradation of organic cations under oxygen and humidity stress. The treated precursor stored under ambient conditions for several days exhibits no condensation reaction products. Due to the synergistic effect of H+ and I-, the perovskite films exhibit a pure perovskite phase and inhibit the formation of abnormal "aggregate" perovskite crystals. Therefore, the additive reacts with FA+ to form new complexes, termed N-(4-methylpyridine)formamidinium), which efficiently passivate nonradiative defects. Consequently, this strategy enables the treated perovskite solar cells to achieve a power conversion efficiency (PCE) of 25.25%, demonstrating enhanced long-term stability under both light and thermal stress. Notably, the optimized device retains 95.5% of its initial PCE after 1200 h of continuous illumination and retains 91.61% of its initial PCE after 600 h at 85 °C and 85% relative humidity.

In recent years, machine learning (ML) has emerged as a versatile tool for accelerating the development of perovskite solar cells (PSCs). A key challenge, however, lies in the scarcity of researchers possessing deep expertise in both material science and artificial intelligence. Pivotal to bridging this gap is ML descriptors, mediating between the empirical language of materials and the numerical inputs for ML algorithms. By translating domain knowledge into computationally tractable forms, the descriptors significantly enhance the model interpretability and empower researchers to uncover the underlying physical mechanisms governing behavior of PSCs. Therefore, it is crucial to overview the efforts translating the structure, property of perovskite materials and performance of PSCs into numerical descriptors compatible with ML models. This review summarized (1) the encoding of crystal structure in perovskites; (2) the quantification of microstructures in perovskite films; (3) the stability assessment of perovskite materials and devices. By synthesizing progress in these aspects, this work lays a solid foundation for constructing a universal model to elucidate the structure‐property‐performance relationships in PSCs, especially in forward prediction and backward inference.

Efficient lead-free and cadmium-free emissive semiconductors are essential for next-generation lighting and display technologies. Copper halides, such as Cs3Cu2I5, have attracted extensive attention in the past few years for their extraordinary optoelectronic properties, excellent environmental stability, and easy solution processability. Copper halide nanocrystals (NCs) can be fabricated using the hot injection approach; however, this approach usually requires sophisticated conditions, such as high temperature and vacuum, which hinder scalability and broader applications. In this work, we report a room-temperature ligand-exchange strategy for fabricating highly emissive Cs3Cu2I5 NCs. Through in situ photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM), we elucidate the critical role of the Cs/Cu ratio in governing the optical and structural properties of the NCs. We also highlight the importance of ligand exchange in terminating crystal growth and achieving colloidally stable NCs, supported by density functional theory (DFT) calculations and Fourier-transform infrared (FTIR) spectroscopy. Guided by these insights, we successfully synthesize highly emissive Cs3Cu2I5 NCs with a narrow size distribution (31.5 +/- 2.9 nm) and a superior PLQY of 94.3%, which is comparable to the best results via hot injection. Notably, the PLQY retains 95% of its initial value after 40 days of storage in ambient air. Our approach is also readily extendable to Cs3Cu2Br5 and Cs3Cu2Cl5 NCs, which exhibit promising PLQYs. This work provides a scalable and cost-effective route for synthesizing high-quality copper halide nanomaterials, advancing their potential for integration into next-generation optoelectronic devices.

Solubility is a fundamental property that governs the growth of perovskite single crystals (SCs). The inverse temperature crystallization (ITC) method, which relies on reduced solubility at elevated temperatures, is widely adopted for synthesizing high-quality perovskite SCs to construct high-performance X-ray detectors. However, many perovskite precursors lack the property of reduced solubilities at high temperatures, exhibiting significant limitations on solvent selection. Here, a temperature-regulated organic-coordination (TROC) mechanism is introduced to overcome the solvent limitation for a wide range of perovskite compositions. By leveraging polyethylene glycol (PEG) as a coordination modulator, a universal solvent system combining PEG and gamma-butyrolactone (GBL) is established for ITC to synthesize perovskite SCs with different compositions. The TROC mechanism operates by dynamically modulating the coordination strength between PEG and perovskites under different temperatures. Specifically, PEG strongly coordinates with Pb2+ ions by displacing both GBL molecules and halide ions, significantly enhancing perovskite solubilities at low temperatures. As temperatures rise, the coordination strength of PEG significantly declines, causing reductions in solubilities and precipitations of perovskite SCs. The synthesized perovskite SCs exhibit excellent qualities, which promotes the application in X-ray detection with high performances. This work provides a new mechanism for synthesizing high-quality perovskite SCs and advances their further applications.

Perovskite solar cells, promising a bright future in the energy market, are now being prioritized for high-throughput production to match their remarkable success at the laboratory scale. However, the use of toxic solvents proved to be one of the major constraints on scaling up production. Herein, a green solvent system consist of dimethyl sulfoxide (DMSO) and 1-dodecyl-3-methylimidazolium chloride ([C12MIM]Cl) ionic liquids (ILs) was developed to modulate the crystallization of wide-bandgap (WBG) perovskite films combined with a antisolvent-free process, i.e., nitrogen (N2) quenching method. The [C12MIM]Cl IL promoted the crystallization of WBG perovskite films with large grain sizes, reduced photo-active PbI2, modulated residual strain, prolonged carrier lifetimes as well as improved energy alignment. Consequently, the [C12MIM]Cl-modified single-junction 1.77eV perovskite solar cells (PSCs) achieved a champion efficiency of 18.75% with an excellent operational stability, retaining an initial PCE of 93% after 2000 h of maximum-power-point tacking test. Meanwhile, the positive effect of the [C12MIM]Cl ILs was universal in perovskite with different bandgaps at 1.53, 1.68 and 1.72eV, respectively. Furthermore, stacking semi-transparent [C12MIM]Cl-modified 1.77eV WBG PSCs as top cells coupled with 1.27eV OPV or 1.24eV Sn-Pb PSC as bottom cells for the 4T tandem configuration showed impressive PCE of 26.01% and 27.44%, respectively. This study opens a new avenue toward the sustainable fabrication of highly efficient and stable perovskite-based semitransparent and tandem solar cells.

The crystallization and growth of perovskite crystals are two crucial factors influencing the performance of perovskite solar cells (PSCs). Moreover, iodoplumbate complexes such as PbI2, PbI3-, and PbI42- in perovskite precursor solution dictate both the quality of perovskite crystals and the optoelectrical performance of PSCs. Here, we propose an iodoplumbate-coordination strategy that employs pentafluorophenylsulfonyl chloride (PTFC) as an additive to tailor the crystal quality. This strategy directly affects the thermodynamics and kinetics of perovskite crystal formation by regulating hydrogen bonds or coordination bonds with Pb2+ or I- ions. Subsequently, the synergistic effect of the PTFC and FA(+) complex was beneficial for intermediate-to-perovskite phase transition, improving the crystalline quality and reducing the defect density in the perovskite film to suppress nonradiative recombination loss. Consequently, the treated PSCs achieved a power conversion efficiency (PCE) of 24.61%, demonstrating enhanced long-term stability under both light and thermal stress. The developed device retained 92.53% of its initial PCE after 1200 h of continuous illumination and 88.6% of its initial PCE after 600 h of 85 degrees C thermal stability tests, respectively, both conducted in N-2 atmospheres.

Mixed components of formamidinium(FA) and cesium (Cs)-based perovskite solar cells are the most hopeful for commercialization owing to their excellent operational and phase stabilities, especially for devices with inverted structure. The nonradiative recombination of carriers can be effectively suppressed through interface optimization, therefore, the performance of devices can be improved. Notably, the buried interface emerges as critical aspects such as charge transport, charge recombination kinetics, and morphology of perovskite films. This study focuses on a straightforward yet effective approach to overcome buried interface challenges between organic polymers (poly(-triarylamine) (PTAA) and FACs-based perovskite films. The PTAA substrate is pretreated with a Lewis base known as 2-butynoic acid (BA) with a C=O functional group. First, it can be an interfacial buffering layer, harmonizing stress mismatch between the perovskite and PTAA layers, consequently optimizing crystallization and improving perovskite film quality. Second, Pb2+ defect can be passivated at the buried interface of the perovskite film through binding with the C=O group of the BA molecule. This dual-function strategy leads to a substantial enhancement in both photoelectric conversion efficiency (PCE) and stability of devices. Finally, the PCE of the device-modified buried interface with BA reaches an impressive 23.33%. Furthermore, unencapsulated devices with BA treatment maintain approximately 94% of their initial efficiency after aging at maximum power point tracking for 1000 h.

Manipulation of interfacial defects and carrier extraction or transport are crucial for improving the operational stability and photovoltaic performance of perovskite solar cells (PSCs). Here, we propose a technique utilizing bridge molecules to construct a carrier viaduct between perovskite bulk and hole-transporting layers. A molecular bridge configuration combining organic functional groups from each layer was used. The designed bridge molecules not only ensure homogeneous contact and promote carrier extraction/transport but also passivate various defects and redistribute the surface potential. The developed device showed an exceptional power conversion efficiency (PCE) of 25.49% with enhanced operational stability. The treated PSCs could retain over 94% of their initial PCEs after 1000 h of continuous operation under 1 sun illumination and over 95% of their initial PCEs after 500 h of aging at approximately 85 C-degrees in dry air with a relative humidity of 20%. This work provides a simple yet effective approach for fabricating perovskite photovoltaics with outstanding performance and operational stability. [GRAPHICS]

Eco-friendly Sn-based perovskites show significant potential for high-performance second near-infrared window light-emitting diodes (900 nm - 1700 nm). Nevertheless, achieving efficient and stable Sn-based perovskite second near-infrared window light-emitting diodes remains challenging due to the propensity of Sn2+ to oxidize, resulting in detrimental Sn4+-induced defects and compromised device performance. Here, we present a targeted strategy to eliminate Sn4+-induced defects through moisture-triggered hydrolysis of tin tetrahalide, without degrading Sn2+ in the CsSnI3 film. During the moisture treatment, tin tetrahalide is selectively hydrolyzed to Sn(OH)4, which provides sustained protection. As a result, we successfully fabricate second near-infrared window light-emitting diodes emitting at 945 nm, achieving a performance breakthrough with an external quantum efficiency of 7.6% and an operational lifetime reaching 82.6 h. Guan et al. report a strategy of moisture-triggered selective hydrolysis of Sn4+ into Sn(OH)4, eliminating Sn4 + -induced defects in tin-based perovskites and enhancing the electron injection in NIR-II LED devices with peak emission of 945 nm and external quantum efficiency of 7.6%.

Formamidinium‐cesium triiodide (FA x Cs 1‐x PbI 3 ) perovskite exhibits excellent phase stability, making it the most promising candidate for commercial perovskite solar cell (PSC) applications, particularly those with inverted structures present a promising contribution to the field of perovskite production. However, this composition often forms small grain sizes and has a large number of defects and PbI 2 residues on its surface, which can damage device performance. In this study, a post‐surface engineering strategy called the “clean‐passivation” method is proposed to address the interfacial problem between the perovskite and the electron transport layer (ETL). This method significantly reduces surface and grain boundary defects and eliminates unreacted PbI 2 , resulting in suppressed iodine decomposition and ion migration during operation. As a result, an excellent power conversion efficiency of 24.27% with superior stability is achieved, as the unencapsulated device maintains 97.12% of its initial efficiency after 1500 h of continuous light soaking. Furthermore, this new surface clean‐passivate strategy can be universally applied to other typical perovskite compositions.

Direct absorption solar collectors (DASC) are extremely attractive in solar energy utilization. In this paper, starting from these two aspects, graphene-based nanofluids, including single-layer graphene (SLG) and graphene oxide (GO), are prepared to enhance solar absorption and photothermal conversion performance. The influence of nanofluids' concentration and two different irradiation modes: traditional DASC and reverse radiation DASC (RI-DASC) on the photothermal conversion performance of graphene-based nanofluids has been studied. The addition of a small amount of SLG or GO significantly improves the photothermal conversion efficiency of base fluid, and it increases along with the increase of the concentration. Furthermore, the RI-DASC mode has a more uniform thermal field distribution and the higher photothermal conversion efficiency than the DASC mode. In DASC mode, the photothermal conversion efficiency of pure water is 17.00%. By changing the irradiation mode, the introduction of GO and SLG nanofluids (100 ppm) increased the photothermal conversion efficiency by about 172% and 189%, reaching 46.26% and 49.13%. According to the photothermal-thermoelectric conversion experiment, the positive correlation between the output power of the TE module and the heating state of the nanofluid makes it possible to adjust the nanofluid in real-time. This work presents a feasible way to enhance solar energy absorption and improve the photothermal conversion efficiency of nanofluids for DASC.

Symbolic classification is an approach of interpretable machine learning for building mathematical formulas that fit certain data sets. In this work, symbolic classification is used to establish the relationship between oxygen vacancy defect formation energy and structural features. We find a structural descriptor n(a)(r(a)/E-na - r(b)), where n(a) is the valence of the a-site ion, r(a) is the radius of the a-site ion, E-na is the electronegativity of the a-site ion, and r(b) is the radius of the b-site ion. It accelerates the screening of defect-free oxide perovskites in advance of density functional theory (DFT) calculations and experimental characterization. Our results demonstrate the potential of symbolic classification for accelerating the data-driven design and discovery of materials with improved properties.

The current work proposes a new strategy to improve solar evaporation efficiency and explore the real applications of volumetric solar evaporation device in desalination and wastewater treatment. Nanofluid based volumetric solar evaporation system is efficient to enhance the absorbance of solar irradiation. However, the solar evaporation efficiencies are relatively low. There is a need to investigate the fundamentals of the limitation and find a new strategy to improve the solar evaporation efficiency. In this paper, a novel device containing tungsten carbide nanofluids as work fluids is designed for the first time to reduce heat loss towards the bulk water, improve the stability of nanofluids, and avoid contamination of nanoparticles. The results show that tungsten carbide nanofluids of 0.3 wt% can harvest 99% of the incident solar energy within 1 cm penetration distance. The photothermal conversion efficiency is 97.7%. The novel device gives an evaporation rate of 1.235 kg m(-2) h(-1) and reached solar evaporation efficiency of 74.9% under 1-sun irradiation. The applications in desalination and wastewater treatment show that the ion rejection rate of seawater is higher than 99.99%, and the content of heavy metal ion is significantly lower than that in the World Health Organization drinking-water standard. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.

Owing to the obvious advantages of direct solar collectors, considerable research has been continuously conducted for improving the efficiency of solar energy storage. Due to the instability in the solar energy reaching the Earth and the uneven distribution of solar irradiation during the day and night, it is difficult to continuously output the heat source. In order to further improve collection system performance, we have proposed a direct absorption solar collector, which uses graphene oxide (GO) nanosheets and titanium nitride (TiN) nanoparticles mixed with heat transfer oil as the working fluids, and uses a ternary mixed molten salt (44% Ca(NO3)(2), 12% NaNO3, and 44% KNO3) as the heat storage core. Moreover, this new kind of collector has been experimentally investigated, and its solar thermal performance is studied with different proportion of GO to TiN in the nanofluids. The experimental results show that the maximum thermal energy can be stored in the collector is nearly 526.96 J, and the energy retention rate can reach 51.7%. Moreover, the solar thermal efficiency of this collector is up to 56.5%. In addition, the mechanism of heat storage is also studied in detail. This study provides a practical avenue for improving the application potential solar collector, which can effectively promote the heat storage for medium temperature of the collector subjected to incident irradiation. (C) 2021 Elsevier B.V. All rights reserved.

Direct absorption solar collector (DASC) is regarded as one of the most promising next-generation solar energy collection technology. Most researches focus on the photothermal performance of working fluids. While the optical boundary condition, which is another important factor influencing the efficiency of DASC, receives little attention. In this paper, the ethylene glycol based TiN nanofluids are used as the research objective. The temperature-dependent optical properties of nanofluids are experimentally investigated in detail, and when the temperature increases from 0 degrees C to 60 degrees C, the optical absorption performance of fluids could enhance similar to 50%, which means that the heated fluids has stronger absorption capability. To improve the photothermal conversion efficiency of collector system, two types of irradiation directions have been studied for the collector, and different heat transfer mode of each type has been experimentally analyzed. The experimental results show that the added nanoparticles can significantly enhance the photothermal conversion efficiency of solar collectors. When the concentration of TiN is 0.003 wt.%, the photothermal conversion efficiency of bottom irradiation mode achieves similar to 45%, much higher than that of side irradiation. However, the side irradiation collector can save similar to 40% of time to reach steady-state compared with the bottom irradiation collector. Moreover, two kinds of collectors have a uniform temperature field (similar to 10 degrees C difference between different depth) over 1.0 cm irradiation depth. Consequently, the prospects for possible applications of ethylene glycol based TiN nanofluids in high-efficiency DASC are presented.

通过改变集热器光学边界条件来改善集热器内部温度场的均匀性,从而有效提升集热器的光热转化效率.研究结果表明:在不同的光学边界条件下,乙二醇基石墨烯纳米片纳米流体具有不同的温度场分布以及不同的集热效率;以乙二醇作为工作流体时,顶部、底部和侧面3种光照模式下集热器光热转化效率分别为27.52％,33.64％和33.25％;以乙二醇基石墨烯纳米片纳米流体作为集热工质,最高集热器光热转化效率分别为59.68％(顶部光照模式,质量分数为0.003％),69.66％(底部光照模式,质量分数为0.005％),60.48％(侧面光照模式,质量分数为0.003％);将石墨烯纳米流体作为集热工质时,集热器光热转化效率提升近1倍.

The nanofluids-based direct absorption solar collector (DASC) is considered as the next-generation solar collection technology due to its high photo-thermal conversion efficiency. However, the key challenges for its development are the large temperature gradients inside nanofluids and the agglomeration of nanoparticles. To address these issues, this paper proposes to apply solar irradiation at the bottom surface of the DASC (i.e. reverse irradiation) rather than at the top surface, which changes the heat transfer mode from heat conduction to heat convection. Experimental test is carried out for the first time for medium-temperature solar collection (-150 degrees C), where titanium nitride is selected as nanoparticles and therminol as base fluid. The experimental results show that reverse irradiation contributes to a uniform temperature distribution in nanofluids and results in a 36.4% higher photo-thermal conversion efficiency compared with the top irradiation; the maximum efficiency can reach up to 80%. What's more, the response time for nanofluids to achieve a steady-state temperature is shortened by 55.6%. One week test shows that reverse irradiation significantly improves the stability of nanofluids and mitigates the agglomeration of nanoparticles. Therefore, it can be concluded that the reverse irradiation DASC is a high-efficient, a fast-response and a long lifetime technology for solar collection. (c) 2020 Elsevier Ltd. All rights reserved.

Solar steam generation is an efficient photo thermal conversion method, which has a wide range of applications in water purification and desalination. With an increasing requirement for technological advancements, the low efficiency of the working media has become a hindrance. In this work, ZrC nanofluid, which has good stability and broad-band absorption capability, was prepared to enhance the volumetric solar steam generation. The effect of ZrC nanoparticle concentration, within a large volume, on a solar steam generation was experimentally studied. It has been found that due to the unique optical absorption characteristics of ZrC nanoparticles, an advantageous temperature gradient with hot irradiation surface layer is attained and the irradiation energy is mostly absorbed by the top surface layer to generate steam. This reduces heat dissipation and improves the evaporation efficiency of the working media. Enhanced solar steam generation by using ZrC nanofluid in the base fluid reduces evaporation costs and expands its applicability in commercial production.