Grain Boundary Engineering with Self-Assembled Porphyrin Supramolecules for Highly Efficient Large-Area Perovskite Photovoltaics

Development of Double Fence Porphyrins as Self-Assembled Monolayers for Tin-Based Perovskite Solar Cells

The MC-series porphyrins, incorporating a variety of thiophene- and dithiophene-containing donor groups, offer an effective passivation strategy to eliminate Sn2+ defects on the surface of tin perovskite. Additionally, the C(15) position of the porphyrin core is linked to various electron-accepting groups, such as 2,1,3-benzothiadiazole, 4-(2,3-diphenylquinoxalin-5-yl)benzoic acid and an indacenodithiophene unit connected to carboxylic acid or cyanoacrylic acid. These groups act as self-assembled monolayers (SAMs) on indium tin oxide (ITO) substrates for tin-based perovskite solar cells (TPSCs). This study is the first example to report the use of porphyrin as SAM for TPSCs. In the presence of SAMs, the devices achieved efficiencies in the following order: MC-4 (8.65%) > MC-3 (6.19%) > MC-2 (5.06%) > MC-1 (5.03%). The outstanding performance of the MC-4 device is attributed to its retarded charge recombination, increased hole mobility, and superior hole-extraction capability. This approach offers a promising pathway for further developing porphyrin-based TPSCs.

Synergistic Surface Reconstruction and Defect Passivation via Guanidine Sulfonate for High-Efficiency Perovskite Photovoltaics

Perovskite films have long suffered from various defects located at grain boundaries and surfaces (GBS), especially residual lead iodide (PbI2), which can seriously impair the photoelectric conversion efficiency (PCE) and long-term stability of the corresponding photovoltaic devices. Herein, guanidine sulfamate (GSM), with desired -NH2, S═O, and Gua+ functional groups, is introduced to the perovskite surface by a post-treatment process to achieve high-quality films with fewer defects. It was found that -NH2 and S═O in GSM contribute to the passivation of various defects in perovskites and suppress non-radiative recombination, thus improving the interfacial carrier transport efficiency. Meanwhile, the guanidine (Gua+) cations promote grain fusion during post-treatment to achieve large-sized grains and effectively reduce residual PbI2 content. Moreover, the optimized perovskite films also exhibited better energy level alignment and surface hydrophobicity. Consequently, the champion PCE of the optimized perovskite solar cells (PSCs) was increased from 21.69 to 23.85% at the appropriate GMS post-treatment concentration, along with a significant improvement in storage stability and light stability.

Interfacial Dipole-Induced High Open-Circuit Voltage for Efficient Perovskite Solar Cells

Solution-processed perovskite films frequently exhibit a high density of defects at their surfaces and grain boundaries, leading to significant nonradiative recombination, hysteresis, and energy losses. Interfacial modification is a crucial strategy for enhancing the photovoltaic performance of perovskite solar cells. In this study, we introduce a polar molecule 3,3,3-trifluoropropionamide (TFAN) with a permanent dipole moment to modify the surface of perovskite films, effectively passivating the uncoordinated Pb2+. The results demonstrate that appropriate interfacial modifications can significantly reduce trap state density and suppress nonradiative recombination, thereby facilitating efficient charge transfer. Without sacrificing photocurrent, the efficiency of TFAN-modified perovskite films increased from 22.21% to 25.17%, while the open-circuit voltage rose from 1.14 to 1.23 V. These enhancements substantially improved the photovoltaic parameters and greatly enhanced operational stability.

High Performance of Cs2AgBiBr6 Perovskite-based Photodetectors by Adding DEAC

Perovskite-based photodetectors (PDs) are broadly utilized in optical communication, non-destructive testing, and smart wearable devices due to their ability to convert light into electrical signals. However, toxicity and instability hold back their mass production and commercialization. The lead-free Cs2AgBiBr6 double perovskite film, promised to be an alternative, is fabricated by electrophoretic deposition (EPD), which compromises film quality. Herein, we improved the quality of the Cs2AgBiBr6 films and the performance of PDs by adding N-acetylethylenediamine (DEAC) to Cs2AgBiBr6 perovskite precursor for EPD, in which the ligand DEAC provides a pair of lone electrons to Bi3+, forming coordinate covalent bonds. The optimized PDs have high detectivity, up to 4.4×1012 Jones, and high stability in the air. The high-performance, flexible Cs2AgBiBr6 perovskite PDs were fabricated on this basis, it also achieved the detectivity up to 3.2×1012 Jones with excellent bending cycle stability. These results propose a feasible approach to improving the crystallization of double perovskite thin films by introducing ligands during the EPD process. Furthermore, they demonstrate enhanced optoelectronic performance, indicating that this method is also applicable to halide perovskites, offering an effective strategy to improve their film quality.

Imperfections Immobilization and Regeneration in Perovskite with Redox-Active Supramolecular Assembly for Stable Solar Cells

Imperfections in metal halide perovskites, such as those induced by light exposure or thermal stress, compromise device performance and stability. A key challenge is immobilizing volatile iodine produced by iodide oxidation and regenerating impurities like elemental lead and iodine. Here, we address this by integrating a redox-active supramolecular assembly of nickel octaethylporphyrin into perovskite film, functioning as both an immobilizer and redox shuttle. Decorated ethyl groups in porphyrin distorts the π ring, increasing the axial ligand adsorption capacity of central metal ion, while reducing intermolecular interactions and promoting iodine adsorption achieving a maximum uptake of 3.83 mg mg-1 to iodine. Adsorbed iodine transfers more electrons to Ni ions, leading to a weakened interaction within I-I bond and facilitating the production of iodide ions. Such a situation further enables selective oxidation of metallic lead defects to Pb2+. Porphyrin supramolecule facilitates hole transport across perovskite grain boundaries, leading to a champion device efficiency of 25.37 % for a 0.10 cm2 active area, outperforms the value of control device being 23.96 %. Modified devices without encapsulation exhibit significantly enhanced stability, maintaining over 90 % of its initial performance after 1,000 hours of continuous 1-sun illumination at maximum power point at 65 °C.

Molecular ferroelectric self-assembled interlayer for efficient perovskite solar cells

The interfacial molecular dipole enhances the photovoltaic performance of perovskite solar cells (PSCs) by facilitating improved charge extraction. However, conventional self-assembled monolayers (SAMs) face challenges like inadequate interface coverage and weak dipole interactions. Herein, we develop a strategy using a self-assembled ferroelectric layer to modify the interfacial properties of PSCs. Specifically, we employ 1-adamantanamine hydroiodide (ADAI) to establish robust chemical interactions and create a dipole layer over the perovskite. The oriented molecular packing and spontaneous polarity of ferroelectric ADAI generate a substantial interfacial dipole, adjusting band bending at the anode, reducing band misalignment, and suppressing charge recombination. Consequently, our formamidinium lead iodide-based conventional PSC achieves efficiencies of 25.13% (0.06 cm2) and 23.5% (1.00 cm2) while exhibiting enhanced stability. Notably, we demonstrate an impressive efficiency of 25.59% (certified at 25.36%) in a 0.06 cm2 area for the inverted champion device, showcasing the promise of ferroelectric SAMs for PSCs performance enhancement.

Direction Modulation of Intramolecular Electric Field Boosts Hole Transport in Phthalocyanines for Perovskite Solar Cells

Tuning the strength of intramolecular electric field (IEF) in conjugated molecules has emerged as an effective approach to boost charge transfer. While direction manipulation of IEF would be a potential way that is still unclear. Here, we leverage the control of peripheral substituents of conjugated phthalocyanines to chemically tune the spatial orientation of IEF. By analyzing the spatial swing of side chains using the Kolmogorov-Arnold representation and least squares algorithm, a comprehensive mathematical-physical model has been established. This model enables rapid evaluation of the IEF and maximum hole transport performance induced by spatial swings. The champion phthalocyanine as dopant-free hole transport material in perovskite solar cell realizes a record performance of 23.41 %. Greatly device stability is also exhibited. This work affords a new way to enhance hole transport capabilities of conjugated molecules by optimizing their IEF vector for photovoltaic devices.

Porphyrin-Based Supramolecular Self-Assemblies: Construction, Charge Separation and Transfer, Stability, and Application in Photocatalysis

As a key means to solve energy and environmental problems, photocatalytic technology has made remarkable progress in recent years. Organic semiconductor materials offer structural diversity and tunable energy levels and thus attracted great attention. Among them, porphyrin and its derivatives show great potential in photocatalytic reactions and light therapy due to their unique large-π conjugation structure, high apparent quantum efficiency, tailorable functionality, and excellent biocompatibility. Compared to unassembled porphyrin molecules, supramolecular porphyrin assemblies facilitate the solar light absorption and improve the charge transfer and thus exhibit enhanced photocatalytic performance. Herein, the research progress of porphyrin-based supramolecular assemblies, including the construction, the regulation of charge separation and transfer, stability, and application in photocatalysis, was systematically reviewed. The construction strategy of porphyrin supramolecules, the mechanism of charge separation, and the intrinsic relationship of assembling structure-charge transfer-photocatalytic performance received special attention. Surfactants, peptide molecules, polymers, and metal ions were introduced to improve the stability of the porphyrin assemblies. Donor-acceptor structure and co-catalysts were incorporated to inhibit the recombination of the photoinduced charges. These increase the understanding of the porphyrin supramolecules and provide ideas for the design of high-performance porphyrin-based photocatalysts.

Probing Nanoscale Charge Transport Mechanisms in Quasi-2D Halide Perovskites for Photovoltaic Applications

Quasi-2D layered halide perovskites (quasi-2DLPs) have emerged as promising materials for photovoltaic (PV) applications owing to their advantageous bandgap for absorbing visible light and the improved stability they enable. Their charge transport mechanism is heavily influenced by the grain orientation of their crystals as well as their nanostructures, such as grain boundaries (GBs) and edge states─the formation of which is inevitable in polycrystalline quasi-2DLP thin films. Despite their importance, the impact of these features on charge transport remains unexplored. In this study, we conduct a detailed investigation on polycrystalline quasi-2DLP thin films and devices, carefully analyzing how grain orientation and nanostructures influence charge transport. Employing nondestructive atomic force microscopy (AFM) topography, along with transient absorption spectroscopy (TAS) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we obtained significant insights regarding the phase purity, crystallographic information, and morphologies of these films. Moreover, our systematic investigation using AFM-based techniques, including Kelvin probe force microscopy (KPFM) and conductive AFM (c-AFM), elucidates the roles played by GBs and edge states in shaping charge transport behavior. In particular, the local band structure along the GBs and edge states within both vertical and parallel grains was found to selectively repel electrons and holes, thus facilitating charge carrier separation. These findings provide perspectives for the development of high-performance quasi-2DLP PV devices and highlight potential approaches that can leverage the intrinsic properties of quasi-2DLPs to advance the performance of perovskite solar cells.

Structural Decoration of Porphyrin/Phthalocyanine Photovoltaic Materials

Porphyrin/phthalocyanine compounds with fascinating molecular structures have attracted widespread attention in the field of solar cells in recent years. In this review, we focus on the pivotal role of porphyrin and phthalocyanine compounds in enhancing the efficiency of solar cells. The review seamlessly integrates the intricate molecular structures of porphyrins and phthalocyanines with their proficiency in absorbing visible light and facilitating electron transfer, key processes in converting sunlight into electricity. By delving into the nuances of intramolecular regulation, aggregated states, and surface/interface structure manipulation, it elucidates how various levels of molecular modifications enhance solar cell efficiency through improved charge transfer, stability, and overall performance. This comprehensive exploration provides a detailed understanding of the complex relationship between molecular design and solar cell performance, discussing current advancements and potential future applications of these molecules in solar energy technology.

Porphyrin-Based Hole-Transporting Materials for Perovskite Solar Cells: Boosting Performance with Smart Synthesis

Perovskite solar cells (PSCs) are becoming a promising and revolutionary advancement within the photovoltaic field globally. Continuous improvement in efficiency, straightforward processing methods, and use of lightweight and cost-effective materials represent superior features, among other notable aspects. Still, long-term stability and durability are issues to address to facilitate widespread commercial adoption and practical application prospects. Research has focused on overcoming these challenges, and charge transport materials play a critical role in determining charge dynamics, photovoltaic performance, and device stability. Conventional hole-transporting materials (HTMs), spiro-OMeTAD and PTAA, contribute to remarkable power conversion efficiencies owing to high thin-film quality and matched energy alignment. However, they often show a high material cost, low carrier mobility, and poor stability, which greatly limit their practical applications. Now, this review outlines recent advances in synthetic approaches to porphyrin-based HTMs to tune the charge dynamics by optimizing their molecular structures and properties. The main structural features comprise porphyrins of A4-type, trans A2B2-type, and photosynthetic pigment analogues. Strategies include well-established routes to provide the required macrocycles, such as condensation of pyrrole or dipyrromethanes with suitable aldehydes, metalation of the porphyrin inner core, and postfunctionalization of peripheral positions. These functionalizations involve conventional procedures (e.g., halogenation, esterification, transesterification, nucleophilic oxidation, reduction, and nucleophilic substitution) as well as metal-catalyzed ones such as Suzuki-Miyaura, Sonogashira, Buchwald-Hartwig, and Ullmann cross-coupling reactions. As HTMs can also protect the perovskite layer from the external environment, porphyrin structures play a pivotal role in chemical, mechanical, and environmental stability, with their high hydrophobicity ability as the most significant parameter. The impact of porphyrins on the hole hopping of other HTMs while acting as an additive or an interlayer, passivating defects, and improving charge transport is also highlighted to provide real insights into ways to develop efficient and stable porphyrin-based materials for PSCs. This perspective aims to guide the scientific community in the design of new porphyrin molecules to place PSCs as an outperformer in photovoltaic technologies.

Selective Photoreforming of Waste Plastics into Diesel Olefins via Single Reactive Oxygen Species

The accumulation of plastic waste poses a pressing environmental challenge. Catalytic conversion stands out as an ideal approach for plastics upcycling, particularly through solar-driven plastics photoreforming. However, due to the common effects of multiple reactive oxygen species (ROS), selectively generating high-value chemicals becomes challenging. In this study, we developed a universal strategy to achieve >85 % selective production of diesel olefins (C15-C28) from polyolefin waste plastics via single ROS. Using tetrakis (4-carboxyphenyl) porphyrin supramolecular (TCPP) with different central metals as an example to regulate single ROS generation, results show Ni-TCPP facilitates triplet exciton production, yielding 1O2, while Zn-TCPP generates ⋅O2 - due to its strong built-in electric field (IEF). 1O2 directly dechlorinates polyvinyl chloride (PVC) due to the electro-negativity of chlorine atoms and the low dissociation energy of C-Cl bonds, while ⋅O2 - promotes direct dehydrogenation of polyethylene (PE) due to the electro-positivity of hydrogen atoms and the high dissociation energy of C-H bonds. This method is universally applicable to various single ROS systems. Installation experiments further affirm the application potential, achieving the highest diesel olefin production of 76.1 μmol h-1. Such a universally adaptive approach holds promise for addressing the global plastic pollution problem.

Enhancement of Photodetector Characteristics by Zn-Porphyrin-Passivated MAPbBr3 Single Crystals

Perovskite single crystals have garnered significant interest in photodetector applications due to their exceptional optoelectronic properties. The outstanding crystalline quality of these materials further enhances their potential for efficient charge transport, making them promising candidates for next-generation photodetector devices. This article reports the synthesis of methyl ammonium lead bromide (MAPbBr3) perovskite single crystal (SC) via the inverse-temperature crystallization method. To further improve the performance of the photodetector, Zn-porphyrin (Zn-PP) was used as a passivating agent during the growth of SC. The optical characterization confirmed the enhancement of optical properties with Zn-PP passivation. On single-crystal surfaces, integrated photodetectors are fabricated, and their photodetection performances are evaluated. The results show that the single-crystalline photodetector passivated with 0.05% Zn-PP enhanced photodetection properties and rapid response speed. The photoelectric performance of the device, including its responsivity (R), external quantum efficiency (EQE), detective nature (D), and noise-equivalent power (NEP), showed an enhancement of the un-passivated devices. This development introduces a new potential to employ high-quality perovskite single-crystal-based devices for more advanced optoelectronics.

Excitonic cuprophilic interactions in one-dimensional hybrid organic-inorganic crystals

The everlasting pursuit of hybrid organic-inorganic lead-free semiconductors has directed the focus towards eco-friendly copper-based systems, perhaps because of the diversity in chemistry, controlling the structure-property relationship. In this work, we report single crystals of a Cu(i) halide-based perovskite-like organic-inorganic hybrid, (TMA)Cu2Br3, (TMA = tetramethylammonium), consisting of unusual one-dimensional inorganic anionic chains of -(Cu2Br3)-, electrostatically stabilized by organic cations, and the Cu(i)-Cu(i) distance of 2.775 Å indicates the possibility of cuprophilic interactions. X-ray photoelectron spectroscopy measurements further confirmed the presence of exclusive Cu(i) in (TMA)Cu2Br3 and electronic structure calculations based on density functional theory suggested a direct bandgap value of 2.50 eV. The crystal device demonstrated an impressive bulk photovoltaic effect due to the emergence of excitonic Cu(i)-Cu(i) interactions, as was clearly visualized in the charge-density plot as well as in the Raman spectroscopic analysis. The single crystals of a silver analogue, (TMA)Ag2Br3, have also been synthesized revealing a Ag(i)-Ag(i) distance of 3.048 Å (signature of an argentophilic interaction). Unlike (TMA)Cu2Br3, where more density of states from Cu compared to Br near the Fermi level was observed, (TMA)Ag2Br3 exhibited the opposite trend, possibly due to variation in the ionic potential influencing the overall bonding scenario.

Moisture-Resilient Perovskite Solar Cells for Enhanced Stability

With the rapid rise in device performance of perovskite solar cells (PSCs), overcoming instabilities under outdoor operating conditions has become the most crucial obstacle toward their commercialization. Among stressors such as light, heat, voltage bias, and moisture, the latter is arguably the most critical, as it can decompose metal-halide perovskite (MHP) photoactive absorbers instantly through its hygroscopic components (organic cations and metal halides). In addition, most charge transport layers (CTLs) commonly employed in PSCs also degrade in the presence of water. Furthermore, photovoltaic module fabrication encompasses several steps, such as laser processing, subcell interconnection, and encapsulation, during which the device layers are exposed to the ambient atmosphere. Therefore, as a first step toward long-term stable perovskite photovoltaics, it is vital to engineer device materials toward maximizing moisture resilience, which can be accomplished by passivating the bulk of the MHP film, introducing passivation interlayers at the top contact, exploiting hydrophobic CTLs, and encapsulating finished devices with hydrophobic barrier layers, without jeopardizing device performance. Here, existing strategies for enhancing the performance stability of PSCs are reviewed and pathways toward moisture-resilient commercial perovskite devices are formulated.

Cu-Modified Palladium Catalysts: Boosting Formate Electrooxidation via Interfacially OHad-Driven Had Removal

Direct formate fuel cells have gained traction due to their eco-friendly credentials and inherent safety. However, their potential is hampered by the kinetic challenges of the formate oxidation reaction (FOR) on Pd-based catalysts, chiefly due to the unfavorable adsorption of hydrogen species (Had). These species clog the active sites, hindering efficient catalysis. Here, we introduce a straightforward strategy to remedy this bottleneck by incorporating Pd with Cu to expedite the removal of Pd-Had in alkaline media. Notably, Cu plays a pivotal role in bolstering the concentration of hydroxyl adsorbates (OHad) on the surface of catalyst. These OHad species can react with Had, effectively unblocking the active sites for FOR. The as-synthesized catalyst of PdCu/C exhibits a superior FOR performance, boasting a remarkable mass activity of 3.62 A mg-1. Through CO-stripping voltammetry, we discern that the presence of Cu in Pd markedly speeds up the formation of adsorbed hydroxyl species (OHad) at diminished potentials. This, in turn, aids the oxidative removal of Pd-Had, leveraging a synergistic mechanism during FOR. Density functional theory computations further reveal intensified interactions between adsorbed oxygen species and intermediates, underscoring that the Cu-Pd interface exhibits greater oxyphilicity compared to pristine Pd. In this study, we present both experimental and theoretical corroborations, unequivocally highlighting that the integrated copper species markedly amplify the generation of OHad, ensuring efficient removal of Had. This work paves the way, shedding light on the strategic design of high-performing FOR catalysts.

P-doped Mn0.5Cd0.5S coupled with cobalt porphyrin as co-catalyst for the photocatalytic water splitting without using sacrificial agents

Photocatalytic water splitting over semiconductors is an important approach to solve the energy demand of human beings. Most photocatalytic H2 generation reactions are conducted in the presence of sacrificial agent. However, the use of sacrificial reagents increases the cost of hydrogen generation. Realizing photocatalytic water splitting for hydrogen production without the addition of sacrificial agents is a major challenge for photocatalysts. The porphyrin MTCPPOMe and P doped MnxCd1-xS make a significant contribution in facilitating the MnxCd1-xS photocatalytic pure water splitting to H2 reaction. Herein, a novel MTCPPOMe/P-MnxCd1-xS (M = 2H, Fe, Co, Ni) composite catalyst which can efficiently split pure water without using sacrificial agents is developed. As a result, the H2 generation rate of CoTCPPOMe/P-Mn0.5Cd0.5S is as high as 2.10 μmol h-1, which is 9.1 and 4.2 times higher than that of Mn0.5Cd0.5S (MCS) and P-Mn0.5Cd0.5S (P-MCS), respectively. P doped MnxCd1-xS inhibits the recombination of photogenerated carriers, and introduction of MTCPPOMe as co-catalyst enhances the reduction capacity. In summary, an efficient and economical photocatalystis prepared for pure water splitting to prepare hydrogen.

Surface Energy Engineering of Buried Interface for Highly Stable Perovskite Solar Cells with Efficiency Over 25

The abundant oxygen-related defects (e.g., O vacancies, O-H) in the TiO2 electron transport layer results in high surface energy, which is detrimental to effective carrier extraction and seriously impairs the photovoltaic performance and stability of perovskite solar cells. Here, novel surface energy engineering (SEE) is developed by applying a surfactant of heptadecafluorooctanesulfonate tetraethylammonium (HFSTA) on the surface of the TiO2 . Theoretical calculations show that the HFSTA-TiO2 is less prone to form O vacancies, leading to lower surface energy, thus improving the carrier-extraction efficiency. The experimental results show that superior perovskite film is obtained due to the reduced heterogeneous nucleation sites and improved crystallization process on the modified TiO2 . Furthermore, the flexible long alkyl chains in HFSTA considerably relieve the compressive stresses at the buried interface. By combining the passivation of TiO2 , crystallization process modulation, and stress relief, a champion PCE up to 25.03% is achieved. The device without encapsulation sustains 92.2% of its initial PCE after more than 2500 h storage under air ambient with relative humidity of 25-30%. The SEE of a buried interface paves a new way toward high-efficiency, stable perovskite solar cells.

Directional Defect Management in Perovskites by In Situ Decom-position of Organic Metal Chalcogenides for Efficient Solar Cells

Directional defects management in polycrystalline perovskite film with inorganic passivator is highly demanded while yet realized for fabricating efficient and stable perovskite solar cells (PSCs). Here, we develop a directional passivation strategy employing a two-dimensional (2D) material, Cu-(4-mercaptophenol) (Cu-HBT), as a passivator precursor. Cu-HBT combines the merits of the targeted modification from organic passivator and excellent stability offered by inorganic passivator. Featuring with dense organic functional motifs on its surfaces, Cu-HBT has the capability to "find" and fasten to the Pb defect sites in perovskites through coordination interactions during a spin-coating process. During subsequent annealing treatment, the organic functional motifs cleave from Cu-HBT and convert in situ into p-type semiconductors, Cu2 S and PbS. The resultant Cu2 S and PbS not only serve as stable inorganic passivators on the perovskite surface, significantly enhancing cell stability, but also facilitate efficient charge extraction and transport, resulting in an impressive efficiency of up to 23.5 %. This work contributes a new defect management strategy by directionally yielding the stable inorganic passivators for highly efficient and stable PSCs.

Donor-π-Acceptor Porphyrin-Assisted Bifunctional Defect Passivation for Enhanced Temporal Domain-/Wavelength-Dependent Nonlinear Absorption Properties in Perovskite Films

Perovskite layer defects are a primary inhibiting factor for their optical nonlinearity, which restricts their use in nonlinear photonics devices. Nevertheless, due to the variety of defect types, the passivation and repair of these defects remain challenging. Herein, a novel bifunctional passivation strategy was proposed, and the porphyrin with a donor-π-acceptor structure was designed to bifunctionally repair perovskite defects by linking different types of functional groups via acetylenic π-conjugated linkage bridges on both sides, thus improving the nonlinear optical (NLO) absorption properties of porphyrin-perovskite hybrid materials. Research results indicate that the amino and carboxyl groups of porphyrins endow the ability to bifunctionally passivate charged defects via effective coordination interactions. The nonlinear absorption properties of all porphyrin-passivated MAPbI3 films were remarkably enhanced compared to that of the MAPbI3 film across multiple wavelengths and temporal domains. Particularly, the Por3-passivated perovskite film (MAPbI3/Por3) exhibited optimized strongest NLO performance, including reverse saturable absorption (RSA) under 800 nm femtosecond (fs) and 1064 nm nanosecond (ns) laser irradiations, as well as saturable absorption (SA) with 515 and 532 nm ns laser excitations. The value of the NLO absorption coefficient (β = 266.23 cm GW-1) is 1 order of magnitude higher than that of the pristine perovskite film (β = 12.93 cm GW-1), also outperforming other porphyrin-passivated perovskite films and some reported materials. The bifunctional passivation mechanism of porphyrin not only intensifies the perovskite's photoinduced ground-state dipole moment in the two-photon absorption (TPA) process and the free carrier absorption ability to deepen the RSA properties under 800 nm fs and 1064 nm ns lasers, respectively, but also enables the improvement of SA responses under 515 nm fs and 532 nm ns lasers by expediting the Pauli blocking effect of perovskite. Our study offers a viable paradigm, which aims at exploiting high-performance NLO perovskite materials across wide spectral regions and time scales.

Porphyrin Supramolecule as Surface Carrier Modulator Imparts Hole Transporter with Enhanced Mobility for Perovskite Photovoltaics

Modulating the surface charge transport behavior of hole transport materials (HTMs) would be as an potential approach to improve their hole mobility, while yet realized for fabricating efficient photovoltaic devices. Here, an oxygen bridged dimer-based monoamine FeIII porphyrin supramolecule is prepared and doped in HTM film. Theoretical analyses reveal that the polaron distributed on dimer can be coupled with the parallel arranged polarons on adjacent dimers. This polaron coupling at the interface of supramolecule and HTM can resonates with hole flux to increase hole transport efficiency. Mobility tests reveal that the hole mobility of doped HTM film is improved by 8-fold. Doped perovskite device exhibits an increased efficiency from 19.8 % to 23.2 %, and greatly improved stability. This work provides a new strategy to improve the mobility of HTMs by surface carrier modulation, therefore fabricating efficient photovoltaic devices.

Advances and prospects of porphyrin derivatives in the energy field

At present, porphyrin is developing rapidly in the fields of medicine, energy, catalysts, etc. More and more reports on its application are being published. This paper mainly takes the ingenious utilization of porphyrin derivatives in perovskite solar cells, dye-sensitized solar cells, and lithium batteries as the background to review the design idea of functional materials based on the porphyrin structural unit in the energy sector. In addition, the modification and improvement strategies of porphyrin are presented by visually showing the molecular structures or the design synthesis routes of its functional materials. Finally, we provide some insights into the development of novel energy storage materials based on porphyrin frameworks.

Modulating Crystallization and Defect Passivation by Butyrolactone Molecule for Perovskite Solar Cells

The attainment of a well-crystallized photo-absorbing layer with minimal defects is crucial for achieving high photovoltaic performance in polycrystalline solar cells. However, in the case of perovskite solar cells (PSCs), precise control over crystallization and elemental distribution through solution processing remains a challenge. In this study, we propose the use of a multifunctional molecule, α-amino-γ-butyrolactone (ABL), as a modulator to simultaneously enhance crystallization and passivate defects, thereby improving film quality and deactivating nonradiative recombination centers in the perovskite absorber. The Lewis base groups present in ABL facilitate nucleation, leading to enhanced crystallinity, while also retarding crystallization. Additionally, ABL effectively passivates Pb²⁺ dangling bonds, which are major deep-level defects in perovskite films. This passivation process reduces recombination losses, promotes carrier transfer and extraction, and further improves efficiency. Consequently, the PSCs incorporating the ABL additive exhibit an increase in conversion efficiency from 18.30% to 20.36%, along with improved long-term environmental stability. We believe that this research will contribute to the design of additive molecular structures and the engineering of components in perovskite precursor colloids.

Reducing nonradiative recombination in perovskite solar cells with a porous insulator contact

Inserting an ultrathin low-conductivity interlayer between the absorber and transport layer has emerged as an important strategy for reducing surface recombination in the best perovskite solar cells. However, a challenge with this approach is a trade-off between the open-circuit voltage (V_oc) and the fill factor (FF). Here, we overcame this challenge by introducing a thick (about 100 nanometers) insulator layer with random nanoscale openings. We performed drift-diffusion simulations for cells with this porous insulator contact (PIC) and realized it using a solution process by controlling the growth mode of alumina nanoplates. Leveraging a PIC with an approximately 25% reduced contact area, we achieved an efficiency of up to 25.5% (certified steady-state efficiency 24.7%) in p-i-n devices. The product of V_oc × FF was 87.9% of the Shockley-Queisser limit. The surface recombination velocity at the p-type contact was reduced from 64.2 to 9.2 centimeters per second. The bulk recombination lifetime was increased from 1.2 to 6.0 microseconds because of improvements in the perovskite crystallinity. The improved wettability of the perovskite precursor solution allowed us to demonstrate a 23.3% efficient 1-square-centimeter p-i-n cell. We demonstrate here its broad applicability for different p-type contacts and perovskite compositions.

Molecular Dipole Modulation of Porphyrins to Enhance Photocatalytic Oxidation Activity for Inactivation of Intracellular Bacteria

The regulation of molecular structures of porphyrin-based photosensitizers is crucial for yielding the effective singlet oxygen as one of the efficient photocatalytic reactive oxidation species. Here, we select methoxy substitution as an electron donor to decorate the porphyrin rings. Introducing a series of metal ions into porphyrin centers further prepares the methoxy-substituted metalloporphyrins (MPs, M = Co, Ni, Cu, Zn), with the hope of modulating their molecular dipole moments and photocatalytic activity. The theoretical calculation analyses show that the metal-free porphyrin center possesses a higher transition dipole and more delocalized orbitals, leading to efficient charge transfer and improved photocatalytic activity. The metalloporphyrin samples are then polymerized by poly(D, l-lactide-co-glycolide) to be applied to in vitro sterilization experiments. As expected, metal-free porphyrin has good antibacterial ability and good biocompatibility. Moreover, the highly effective bacteriostatic metal-free porphyrin achieves satisfactory photodynamic therapeutic outcomes against intracellular pathogens in cancer cells. This work demonstrates that the molecular dipole modulation of porphyrins is critical for their photocatalytic oxidation and antibacterial ability.

Spontaneous Formation of Heterostructured Perovskite Films for Photovoltaic Application

Perovskite solar cells (PSCs) are the one of most promising photovoltaic technologies that can be achieved by a simple solution process. At the current stage, the key issues concern further improvements in efficiency and operational lifetime. Constructing a self-assembled perovskite structure with manipulated chemical and physical properties is a useful and effective strategy to solve these problems. Herein, we review the basic principles of and recent progress in the spontaneous formation behavior of heterostructured perovskite thin films. This concept provides insightful clues for the design and fabrication of stable and efficient PSCs for next-generation photovoltaics.

Bismuth and antimony halometalates containing photoswitchable ruthenium nitrosyl complexes

The first examples of Bi(III) and Sb(III) halide compounds combined with a photoswitchable ruthenium nitrosyl unit are reported. The structures of [RuNOPy₄Br]₄[Sb₂Br₈][Sb₃Br₁₂]₂ (1) and (H₃O)[RuNOPy₄Br]₄[Bi₂Br₉]₃·3H₂O (2) were determined by X-ray diffraction, and exhibit three different structural types of group 15 halometalates. Low-temperature IR-spectroscopy measurements reveal that the irradiation of 1 at 365 nm switches a stable Ru-NO (GS) unit to a metastable Ru-ON (MS1) linkage. Moreover, the light excitation of 2 at 365 or 405 nm induces the additional formation of a side-bond isomer Ru-η²-(NO) (MS2). The reverse reactions MS1/MS2 → GS can be induced by red-infrared light irradiation or by heating at temperatures >200 K. The obtained synthetic and spectroscopic data open the way for the preparation of hybrid halide complexes with a variety of photoswitchable complexes (NO₂, SO₂, N₂, etc.), and give an insight into the behavior of light-induced species embedded in polynuclear halides.

Conformal Imidazolium 1D Perovskite Capping Layer Stabilized 3D Perovskite Films for Efficient Solar Modules

Although the perovskite solar cells have been developed rapidly, the industrialization of perovskite photovoltaics is still facing challenges, especially considering their stability issues. Here, the new type of benzimidazolium salt, N,N'-dialkylbenzimidazolium iodide, is proposed and functionalized to convert the three-dimensional (3D) FACs-perovskite films into one-dimensional (1D) capping layer topped 1D/3D structure either in individual device or module levels. This conformal interface modulation demonstrates that not only can effectively stabilize FACs-based perovskite films by inhibiting the lateral and vertical iodide diffusions in devices or modules, ensuring an excellent operation and environmental stability, but also provides an excellent charge transporting channel through the well-designed 1D crystal structure. Consequently, efficient device performance with power conversion efficiency up to 24.3% is readily achieved. And the large-area perovskite solar modules with high efficiency (19.6% for the active areas of 18 cm2 ) and long-term stability (about 500 h in AM 1.5G illumination or about 1000 h under double-85 conditions) are also successfully verified.

Construction of a Highly Anisotropic Supramolecular Assembly Assisted by a Dimensional Confinement Space: Toward Perovskite Solar Cells

Solution-processed polycrystalline perovskites (PVKs) have aroused tremendous interest in the optoelectronic device field. However, the inherent high-density defects in the polycrystalline hindered achieving efficient and stable large-area PVK solar cells (PSCs). Although organic molecules are already employed to passivate PVK defects, they are insulating by nature, limiting the carrier transport. Here, we design an assembly of a small molecule (N,N'-di(propanoic acid)-perylene-3,4,9,10-tetracarboxylic diamide, PDI) via confinement-assisted supramolecular polymerization technology, which is used as a binder for grain boundaries to simultaneously passivate defects and promote carrier transport. The synergistic effect allows the efficiency of all-air processed carbon-based PSCs to reach a decent power conversion efficiency of 14.17%. Importantly, the as-prepared supramolecular assembly completely breaks through the insulating nature of the single molecule, which exists in the long-term defect passivation of PSCs by organic molecules. It is expected that this finding may provide novel design ideas to apply the assemblies to improve the performance of PSCs.

Surfactant Tween 20 Controlled Perovskite Film Fabricated by Thermal Blade Coating for Efficient Perovskite Solar Cells

In recent years, additive engineering has received considerable attention for the fabrication of high-performance perovskite solar cells (PSCs). In this study, a non-ionic surfactant, polyoxyethylene (20) sorbitan monolaurate (Tween 20), was added as an additive into the MAPbI₃ perovskite layer, and the thermal-assisted blade-coating method was used to fabricate a high-quality perovskite film. The Tween 20 effectively passivated defects and traps in the MAPbI₃ perovskite films. Such a film fabricated with an appropriate amount of Tween 20 on the substrate showed a higher photoluminescence (PL) intensity and longer carrier lifetime. At the optimal concentration of 1.0 mM Tween 20, the performance of the PSC was apparently enhanced, and the champion PSC demonstrated a PCE of 18.80%. Finally, this study further explored and compared the effect on the device performance and ambient stability of the MAPbI₃ perovskite film prepared by the spin-coating method and the thermal-assisted blade coating.

Defect Passivation by a Multifunctional Phosphate Additive toward Improvements of Efficiency and Stability of Perovskite Solar Cells

The quality of perovskite films plays a crucial role in the performance of the corresponding devices. However, the commonly employed perovskite polycrystalline films often contain a high density of defects created during film production and cell operation, including unsaturated coordinated Pb²⁺ and Pb⁰, which can act as nonradiative recombination centers, thus reducing open-circuit voltage. Effectively eliminating both kinds of defects is an important subject of research to improve the power conversion efficiency (PCE). Here, we employ hydrogen octylphosphonate potassium (KHOP) as a multifunctional additive to passivate defects. The molecule is introduced into perovskite precursor solution to regulate the perovskite film growth process by coordinating with Pb, which can not only passivate the Pb²⁺ defect but also effectively inhibit the production of Pb⁰; at the same time, the presence of K⁺ reduces device hysteresis by inhibiting I^- migration and finally realizes double passivation of Pb²⁺ and I^--based defects. Moreover, the moderate hydrophobic alkyl chain in the molecule improves the moisture stability. Ultimately, the optimal efficiency can reach 22.21%.

Study of Intermolecular Interaction between Small Molecules and Carbon Nanobelt: Electrostatic, Exchange, Dispersive and Inductive Forces

The conjugated structure of carbon is used in chemical sensing and small molecule catalysis because of its high charge transfer ability, and the interaction between carbon materials and small molecules is the main factor determining the performance of sensing and catalytic reactions. In this work, Reduced Density Gradient (RDG) and Symmetry-Adapted Perturbation Theory (SAPT) energy decomposition methods were used in combination to investigate the heterogeneity of catalytic substrates commonly used in energy chemistry with [6, 6] the carbon nanobelt ([6, 6] CNB, the interaction properties and mechanisms inside and outside the system). The results show that most of the attractive forces between dimers are provided by dispersive interactions, but electrostatic interactions cannot be ignored either. The total energy of the internal adsorption of [6, 6] CNB was significantly smaller than that of external adsorption, which led to the small molecules being more inclined to adsorb in the inner region of [6, 6] CNB. The dispersive interactions of small molecules adsorbed on [6, 6] CNB were also found to be very high. Furthermore, the dispersive interactions of the same small molecules adsorbed inside [6, 6] CNB were significantly stronger than those adsorbed outside. In [6, 6] CNB dimers, dispersion played a major role in the mutual attraction of molecules, accounting for 70% of the total attraction.

Crystal Growth Regulation of 2D/3D Perovskite Films for Solar Cells with Both High Efficiency and Stability

Reducing the electronic defects in perovskite films has become a substantial challenge to further boost the photovoltaic performance of perovskite solar cells. Here, 2D (NpMA)₂ PbI₄ perovskite and 1-naphthalenemethylammonium iodide (NpMAI) are separately introduced into the PbI₂ precursor solutions to regulate the crystal growth in a 2D/3D perovskite film using a two-step deposition method. The (NpMA)₂ PbI₄ modulated perovskite film shows a significantly improved film quality with enlarged grain size from ≈500 nm to over 1000 nm, which greatly reduces the grain-boundary defects, improves the charge carrier lifetime, and hinders ionic diffusion. As a result, the best-performing device shows a high power conversion efficiency (PCE) of 24.37% for a small-area (0.10 cm^-2 ) device and a superior PCE of 22.26% for a large-area (1.01 cm^-2 ) device. Importantly, the unencapsulated device shows a dramatically improved operational stability with maintains over 98% of its initial efficiency after 1500 h by maximum power point (MPP) tracking under continuous light irradiation.

Hot-Air Treatment-Regulated Diffusion of LiTFSI to Accelerate the Aging-Induced Efficiency Rising of Perovskite Solar Cells

Perovskite solar cells (PSCs) with LiTFSI-doped Spiro-OMeTAD as the hole transport layer (HTL) generally require aging in the air to achieve high efficiency (a.k.a. aging-induced efficiency rising), but attention is rarely paid to the synergistic effects of temperature and humidity during the ambient aging. In this work, based on the understanding of the doping mechanism of Spiro-OMeTAD, we develop an ambient condition-controlled hot-air treatment (HAT) for such kinds of PSCs to further improve the device efficiency and relieve the photocurrent hysteresis. After storing the PSCs at a temperature of 35-40 °C and humidity of 35-40% RH for 30 min, efficient redistribution of LiTFSI in Spiro-OMeTAD enables much-increased conductivity due to the increased concentration of Spiro-OMeTAD⁺·O₂^- and Spiro-OMeTAD⁺·TFSI^-, leading to an enhanced fill factor. From the light intensity-dependent V_oc and capacitance-voltage measurements, the V_oc enhancement is proven to be originated from the change in dominant recombination type from trap-assisted interfacial recombination to bulk Shockley-Read-Hall recombination and the improved carrier dynamics at the perovskite/HTL interface. Furthermore, the decreased density and migration of shallow-level charge traps result in the negligible hysteresis of treated devices. Our work provides new insights into the effect of ambient aging on PSCs with Spiro-OMeTAD and reveals the potentials of HAT to improve the device performance.