Research progress on hybrid organic–inorganic perovskites for photo-applications

Recent advances in metal halide perovskite based photocatalysts for artificial photosynthesis and organic transformations

Metal halide perovskites (MHP) emerged as highly promising materials for photocatalysis, offering significant advancements in the degradation of soluble and airborne pollutants, as well as the transformation of functional organic compounds. This comprehensive review focuses on recent developments in MHP-based photocatalysts, specifically examining two major categories: lead-based (such as CsPbBr3) and lead-free variants (e.g. Cs2AgBiX6, Cs3Bi2Br9 and others). While the review briefly discusses the contributions of MHPs to hydrogen (H2) production and carbon dioxide (CO2) reduction, the main emphasis is on the design principles that determine the effectiveness of perovskites in facilitating organic reactions and degrading hazardous chemicals through oxidative transformations. Furthermore, the review addresses the key factors that influence the catalytic efficiency of perovskites, including charge recombination, reaction mechanisms involving free radicals, hydroxyl ions, and other ions, as well as phase transformation and solvent compatibility. By offering a comprehensive overview, this review aims to serve as a guide for the design of MHP-based photocatalysis and shed light on the common challenges faced by the scientific community in the domain of organic transformations.

Efficient charge transfer in Co-doped CeO2/graphitic carbon nitride with N vacancies heterojunction for photocatalytic hydrogen evolution

Photocatalytic hydrogen evolution is a promising and environmentally friendly strategy to prepare renewable energy sources thus addressing the energy crisis and environmental issues, and it is crucial to develop an ideal photocatalytic for highly efficient H₂ production. Herein, the Co-doped CeO₂ decorated on graphitic carbon nitride with N vacancies (NVs) heterostructure photocatalyst (Co-CeO₂/DCN) is prepared via a simple self-assembly method. Due to the extended light absorption range, and efficient charge separation and migration derived from the introduction of NVs and the heterojunction structure, the photocatalytic activity of the Co-CeO₂/DCN is largely promoted. The optimal sample 20-Co-CeO₂/DCN shows a high H₂ evolution rate of 1077.02 μmol g^-1h^-1 (λ > 400 nm), which is 113 and 33 times higher than the bare bulk graphitic carbon nitride (BCN) and CeO₂, respectively. This work will provide a new strategy to develop high-performance photocatalysts using defect engineering and heterojunction engineering for H₂ evolution.

Methylpiperazine based 0D chiral hybrid lead halides for second harmonic generation

Hybrid organic-inorganic metal halides (HOMHs) have recently attracted broad research interest for their structural tunability and remarkable optoelectronic properties. Among them, chiral HOMHs have demonstrated promising applications in second-order nonlinear optics (NLO) on account of their inherent noncentrosymmetric structures. Herein, we synthesized two new chiral HOMHs, (S-/R-2-C₅H₁₄N₂)₂PbI₆, based on S-/R-2-methylpiperazine chiral amines. They feature a band gap close to 2.9 eV with high phase purity as well as environmental and thermal stability. The induction of the chiral optical properties of (S-/R-2-C₅H₁₄N₂)₂PbI₆ by chiral organic cations was verified by circular dichroism (CD) spectroscopy. Moreover, the resulted HOMHs materials demonstrate a strong second harmonic generation response with a large laser damage threshold (∼2.97 mJ cm^-2), showing promising applications in NLO photonic devices.

Interface Modification with CuCrO2 Nanocrystals for Highly Efficient and Stable Planar Perovskite Solar Cells

The interfaces between the absorber and charge transport layers are shown to be critical for the performance of perovskite solar cells (PSCs). PSCs based on the Spiro-OMeTAD hole transport layers generally suffer from the problems of stability and reproducibility. Inorganic hole transport materials CuCrO₂ have good chemical stability and high hole mobility. Herein, we reported the preparation of the delafossite-type CuCrO₂ nanocrystals with a template-etching-calcination method and the incorporation of the as-obtained CuCrO₂ nanocrystals at the perovskite/Spiro-OMeTAD interfaces of planar PSCs to improve the device efficiency and stability. Compared with the traditional hydrothermal method, the template-etching-calcination method used less calcination time to prepare CuCrO₂ nanocrystals. After the CuCrO₂ interface modification, the efficiency of PSCs improved from 18.08% to 20.66%. Additionally, the CuCrO₂-modified PSCs showed good stability by retaining nearly 90% of the initial PCE after being stored in a drybox for 30 days. The template-etching-calcination strategy will pave a new approach for the synthesis of high-performance inorganic hole-transporting materials.

A new organic–inorganic hybrid perovskite ferroelectric [ClCH2CH2N(CH3)3][PbBr3] and Its PVDF matrix-assisted highly-oriented flexible ferroelectric films

A hybrid perovskite with dielectric, SHG, and ferroelectric triple transitions was tailored into highly-oriented films using PVDF matrix-assisted in situ growth.

Cu-Organic framework-derived V-doped carbon nanostructures for organic dye removal

Metal-organic frameworks (MOFs) have recently emerged as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate hierarchical porous-carbon-related nanostructured functional materials. In this work, we used Cu(II) ions and aromatic dicarboxylic acid to construct [Cu₃(4,4'-oba)₂(μ₂-OH)₂(H₂O)₂]_n (4,4'-H₂oba = 4,4'-oxybisbenzoic acid) as a precursor for the preparation of carbon nanostructures. Doping foreign elements into intrinsic MOF-based nanomaterials is an effective way to enhance the adsorption property and photocatalytic activity; thus, we designed a facile method to synthesize a vanadium-doped mixture of Cu₂O and Cu nanoparticles encapsulated in a Cu-MOF-derived carbon nanostructure (C-V-1) in this work for the first time. Benefiting from the protection of the carbon shell and regulation of the electronic structure by doping vanadium and phase-mixing Cu₂O and Cu, the adsorption capacities of C-V-1 for MB, RhB, MO, CR and GV at room temperature are 174.13, 147.06, 179.92, 275.90 and 611.81 mg g^-1 in 240 min, respectively, while the photocatalytic degradation rates are 88.14% for MB, 79.80% for RhB, 71.31% for MO, and 71.19% for CR after 4 h. In addition, the degradation rate is larger than 99.01% for GV after only 30 min of UV irradiation. This strategy of using a diverse MOF as a structural and compositional material to create a multifunctional composite/hybrid may expand the opportunities to explore highly efficient, fast and robust adsorbents and photocatalysts for water treatment.

Exploring the charge injection aptitude in pyrazol and oxazole derivatives by the first-principles approach

Azole derived products acquired significant consideration in everyday life based on their improved biological potential to the semiconducting substances. The research focused in-depth within pyrazol, and oxazole compounds 1–4 concerning charge transport, structural, optical as well as electronic properties. The density functional theory (DFT) along with time-dependent DFT were used for the optimization of their ground state geometries and excitation energies. We also investigated the molecule’s electron coupling constants (|V RP|) as well as electron injection (ΔG inject) values. For better understanding, charge transport and electronic characteristics were performed through quantum chemical computations. The |V RP| and ΔG inject values of pyrazole, as well as oxazole molecules, exhibited that these compounds could be competent for dye-sensitized solar cell applications. The pyrazole higher diagonal band gap enlightening these might have enhanced fill factor (FF) along with short-circuit current density (J sc ). We have also explored the electron injection, energy level offset, dissociation of excitons, and band alignment of studied compounds to shed light on the functionality of these compounds for photovoltaic and semiconductor device applications.

Hardware implementation of photoelectrically modulated dendritic arithmetic and spike-timing-dependent plasticity enabled by an ion-coupling gate-tunable vertical 0D-perovskite/2D-MoS2 hybrid-dimensional van der Waals heterostructure

Brain-inspired nanodevices have been demonstrated to possess outstanding characteristics for implementing neuromorphic computing. Among these devices, photoelectrically modulated neuromorphic transistors are regarded as the basic building blocks for applications in emerging brain-like devices. However, to date, efficient optoelectronic-hybrid neuromorphic devices are still lacking. Because conventional transistors based on mono-semiconductor materials cannot absorb adequate light to ensure efficient light-matter interactions, they pose significant challenges to the synchronous processing of photoelectric information. Here, a novel photoelectrically modulated neuromorphic device based on an ion-coupling gate-tunable vertical 0D-CsPbBr3-quantum-dots/2D-MoS2 hybrid-dimensional van der Waals heterojunction is demonstrated by using a polymer ion gel electrolyte as the gate dielectric. A super-efficient heterojunction interface for photo-carrier transport is developed by integrating CsPbBr3 quantum dots with 2D-layered MoS2 semiconductors. We experimentally demonstrate that the drain-source current can be modulated by applying spikes to the drain and gate terminals, and the conductance can also be tuned by external light stimulus. Most importantly, photoelectrically modulated spiking Boolean logics, dendritic integrations in both temporal and spatial modes, and Hebbian learning rules can be successfully mimicked in our proposed hybrid-dimensional device using this intriguing optical and electrical synergy approach. These results suggest that the proposed device has great potential in intelligent cognitive systems and neuromorphic computing applications.