Biological ion channels play a critical role in the complex physiological processes of living organisms. Inspired by these natural systems, we demonstrate the fabrication of ultrathin 2D copper-based metal-organic framework (CuMOF) films and their application to mimic key functionalities of biological membranes. Using a liquid-air interface synthesis technique, we synthesized CuMOF films with tunable thicknesses ranging from 1.4 nm to 20 nm over centimeter-scale areas. These membranes exhibit well-defined nanoporous structures of pore diameter 1.5 nm that facilitate nanofluidic ion transport. The ionic conductance of the CuMOF films strongly depends on both film thickness and electrolyte concentration, demonstrating surface-charge-dominated transport and Na+ selective ion conduction at low ionic strengths. Moreover, this selective ion transport enables osmotic energy generation under a concentration gradient. Additionally, the CuMOF films exhibit ionic memristive behavior, including reversible synaptic potentiation and depression, closely resembling synaptic plasticity. This study presents a scalable, tunable platform for developing bioinspired ionic devices with potential applications in selective ion transport, nanofluidic energy harvesting, and neuromorphic computing.

Improving the dispersion of colloidal quantum dots (QDs) within organic semiconductor (OSC) matrices remains critical for advancing hybrid nanocomposite optoelectronic technologies. This study investigates how film-deposition kinetics influence the morphology of TIPS-tetracene (TIPS-Tc):PbS QD blends, comparing spin-coating and blade coating for QDs ligated with either native oleic acid (OA) or a matched carboxylic acid functionalised tetracene analogue (TET-CA). Films spun-cast at low spin speeds form highly crystalline TIPS-Tc domains with highly aggregated QDs. Increased spin speed induces a deeper solvent quench, driving rapid TIPS-Tc nucleation while kinetically arresting QD diffusion, which improves QD dispersion within the crystalline matrix. TIPS-Tc:PbS-OA blends typically exhibit poor QD dispersibility due to poor matching between the OA ligands and the TIPS-Tc matrix. This work demonstrates that through employing high spin speeds QD dispersibilities may be significantly enhanced, even for PbS-OA, a significant step demonstrating that QD-OSC surface chemistries may not have to be fully matched to attain desired, well-dispersed morphologies. In contrast, blade-coating proceeds under slower solvent removal, resulting in weakly crystalline TIPS-Tc and extensive QD aggregation due to extended diffusion and delayed nucleation. These findings reveal the critical role of processing kinetics in directing OSC-QD self-assembly, essential for the optimisation of nanocomposite morphologies for next-generation optoelectronic devices.

Advanced photonic materials showing two-photon absorption (2PA) have been widely explored to develop three-dimensional imaging, micro and nanofabrication, all-optical switching, lithography on a nanoscale and many other enabling technologies. These all require nonlinear absorption chromophores with intrinsic 2PA cross-sections and long-term photo- and thermal stability. Here, we disclose the very first example of the dipolar carbene-metal-amide (CMA) material showing a enhanced 2PA cross-section up to 105 GM. Overall molecular design considerations such as extended π-conjugation (to increase polarizability), minimizing the singlet-triplet energy gap (ΔEST), and using heavy metal atoms are the first design principles to obtain bright one- and two-photon excited thermally activated delayed fluorescence (TADF) material, showing one of the highest radiative rate of 2.18·106 s-1 across CMA materials. Bright red CMA 2P-TADF material shows excellent photostability (LT50 = 3 h) to 20 mW femtosecond pulsed laser excitation at 1000 nm, encouraging further CMA exploration for future applications in advanced photonic technologies requiring third-order nonlinear optical properties.

Nanocomposite films combining organic semiconductors (OSCs) and colloidal quantum dots (QDs) are promising systems for next-generation optoelectronic technologies such as singlet-fission photon multiplication (SF-PM). Here, we show that tuning the solubilizing substituents on the high-triplet-energy SF-OSC (1E,3E,5E)-1,6-diphenylhexa-1,3,5-triene (DPH) enables precise control over film morphology and QD dispersibility. Grazing-incidence X-ray scattering reveals that PbS QDs ligated with oleic acid are poorly dispersed in all DPH derivatives, whereas hexanoic acid or DPH-carboxylic acid ligands significantly improve QD dispersibility. A clear design rule emerges: increasing solubilizing group volume relative to the DPH core enhances QD dispersibility, enabling well-dispersed QDs even in highly ordered DPH matrices. An exception arises in a derivative that forms an amorphous, nonequilibrium morphology that fully disperses QDs, but later crystallizes, resulting in QD aggregation. These findings show that OSC:QD nanocomposites require co-optimization of ligand-OSC chemistry and crystallization kinetics, providing a framework for designing efficient SF-PM and related technologies.

Despite the potential of poly(2-methacryloyloxy ethyl phosphorylcholine)-poly(2-(diisopropylamino)ethyl methacrylate) (PMPC-PDPA) diblock copolymer nanoparticles for several biological applications, the exact mechanism of pH-induced self-assembly of the PMPC-PDPA chains into nanoparticles remains unclear, although it has been extensively studied by ex situ transmission electron microscopy. Here, we probe this process using time-resolved small-angle X-ray scattering (TR-SAXS) to gain an understanding of the phenomena that occur on the nanoscale. Modeling the TR-SAXS data indicated that spherical micelles and vesicles were formed at a pH as low as 3, and the spherical micelle and vesicle structures reformed at pH 5.5. At pH ∼5.5, insoluble PMPC25-PDPA70 diblock copolymer precipitation was also observed by SAXS. A huge soluble PMPC25-PDPA70 diblock copolymer reservoir might assist in PMPC25-PDPA70 vesicle construction. Additionally, a potential pathway of vesicle construction by spherical micelle fusion was supported by the SAXS evidence.

Perovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which highly effective precursor phases for subsequent transformation to alpha-formamidinium lead triiodide (FAPbI3), fully processed under ambient conditions. PSCs utilising our FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and "damp heat" (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the alpha-phase.

Singlet fission in organic chromophores holds the potential for enhancing photovoltaic efficiencies beyond the single-junction limit. The most basic requirement of a singlet fission material is that it has a large energy gap between its first singlet and triplet excited states. Identifying such compounds is not simple and has been accomplished either through computational screening or by subtle modifications of previously known fission materials. Here, we propose an approach that leverages ground and excited-state aromaticity combined with double-bond conformation to establish simple qualitative design rules for predicting fundamental optical properties without the need for computational modeling. By investigating two Pechmann dye isomers, we demonstrate that although their planarity and degree of charge transfer are similar, singlet fission is active in the isomer with a trans-conformation, while the cis-isomer exhibits greater favorability for polaronic processes, experimentally validated using ultrafast and electron spin resonance spectroscopy. Our results offer a new design perspective that provides a rational framework for tailoring optoelectronic systems to specific applications such as singlet fission or triplet-triplet annihilation

AbstractPerovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which we use as highly effective precursor phases for subsequent transformation to α-formamidinium lead triiodide (α-FAPbI3), fully processed under ambient conditions. PSCs utilising our α-FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and “damp heat” (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the α-phase.

Blends comprising organic semiconductors and inorganic quantum dots (QDs) are relevant for many optoelectronic applications and devices. However, the individual components in organic-QD blends have a strong tendency to aggregate and phase-separate during film processing, compromising both their structural and electronic properties. Here, we demonstrate a QD surface engineering approach using electronically active, highly soluble semiconductor ligands that are matched to the organic semiconductor host material to achieve well-dispersed inorganic-organic blend films, as characterized by X-ray and neutron scattering, and electron microscopies. This approach preserves the electronic properties of the organic and QD phases and also creates an optimized interface between them. We exemplify this in two emerging applications, singlet-fission-based photon multiplication (SF-PM) and triplet-triplet annihilation-based photon upconversion (TTA-UC). Steady-state and time-resolved optical spectroscopy shows that triplet excitons can be transferred with near unity efficiently across the organic-inorganic interface, while the organic films maintain efficient SF (190% yield) in the organic phase. By changing the relative energy between organic and inorganic components, yellow upconverted emission is observed upon 790 nm NIR excitation. Overall, we provide a highly versatile approach to overcome longstanding challenges in the blending of organic semiconductors with QDs that have relevance for many optical and optoelectronic applications.

Singlet fission is a photophysical process that provides a pathway for more efficient harvesting of solar energy in photovoltaic devices. The design of singlet fission candidates is non-trivial and requires careful optimization of two key criteria: (1) correct energetic alignment and (2) appropriate intermolecular coupling. Meanwhile, this optimization must not come at the cost of molecular stability or feasibility for device applications. Cibalackrot is a historic and stable organic dye which, although it has been suggested to have ideal energetics, does not undergo singlet fission due to large interchromophore distances, as suggested by single crystal analysis. Thus, while the energetic alignment is satisfactory, the molecule does not have the desired intermolecular coupling. Herein, we improve this characteristic through molecular engineering with the first synthesis of an aza-cibalackrot and show, using ultrafast transient spectroscopy, that singlet fission is successfully "turned on."

Organic-inorganic nanocomposite films formed from blends of small-molecule organic semiconductors and colloidal quantum dots are attractive candidates for high efficiency, low-cost solar energy harvesting devices. Understanding and controlling the self-assembly of the resulting organic-inorganic nanocomposite films is crucial in optimising device performance, not only at a lab-scale but for large-scale, high-throughput printing and coating methods. Here, in situ grazing incidence X-ray scattering (GIXS) gives direct insights into how small-molecule organic semiconductors and colloidal quantum dots self-assemble during blade coating. Results show that for two blends separated only by a small difference in the structure of the small molecule forming the organic phase, crystallisation may proceed down two distinct routes. It either occurs spontaneously or is mediated by the formation of quantum dot aggregates. Irrespective of the initial crystallisation route, the small-molecule crystallisation acts to exclude the quantum dot inclusions from the growing crystalline matrix phase. These results provide important fundamental understanding of structure formation in nanocomposite films of organic small molecules and colloidal quantum dots prepared via solution processing routes. It highlights the fundamental difference to structural evolution which can be made by seemingly small changes in system composition. It provides routes for the structural design and optimisation of solution-processed nanocomposites that are compatible with the large-scale deposition manufacturing techniques that are crucial in driving their wider adoption in energy harvesting applications.

The poor operational stability of non-fullerene electron acceptor (NFA) organic solar cells (OSCs) currently limits their commercial application. While previous studies have primarily focused on the degradation of the NFA component, we also consider here the electron donor material. We examine the stability of three representative donor polymers, PM6, D18, and PTQ10, paired with the benchmark NFA, Y6. After light soaking PM6 and D18 in air, we find an enhanced conversion of singlet excitons into trapped interchain polaron pairs on sub-100 femtosecond timescales. This process outcompetes electron transfer to Y6, significantly reducing the charge generation yield. However, this pathway is absent in PTQ10. We identify twisting in the benzo[1,2-b:4,5-b′]dithiophene (BDT)-thiophene motif shared by PM6 and D18 as the cause. By contrast, PTQ10 does not contain this structural motif and has improved stability. Thus, we show that the donor polymer can be a weak link for OSC stability, which must be addressed collectively with the NFA.

Narrow bandgap conjugated polymers are a heavily studied class of organic semiconductors, but their excited states usually have a very short lifetime, limiting their scope for applications. One approach to overcome the short lifetime is to populate long-lived triplet states for which relaxation to the ground state is forbidden. However, the triplet lifetime of narrow bandgap polymer films is typically limited to a few microseconds. Here, we investigated the effect of film morphology on triplet dynamics in red-emitting conjugated polymers based on the classic benzodithiophene monomer unit with the solubilizing alkyl side chains C16 and C2C6 and then used Pd porphyrin sensitization as a further strategy to change the triplet dynamics. Using transient absorption spectroscopy, we demonstrated a 0.45 ms triplet lifetime for the more crystalline nonsensitized polymer C2C6, 2-3 orders of magnitude longer than typically reported, while the amorphous C16 had only a 5 μs lifetime. The increase is partly due to delaying bimolecular electron-hole recombination in the more crystalline C2C6, where a higher energy barrier for charge recombination is expected. A triplet lifetime of 0.4 ms was also achieved by covalently incorporating 5% of Pd porphyrin into the C16 polymer, which introduced extra energy transfer steps between the polymer and porphyrin that delayed triplet dynamics and increased the polymer triplet yield by 7.9 times. This work demonstrates two synthetic approaches to generate the longest-lived triplet excited states in narrow bandgap conjugated polymers, which is of necessity in a wide range of fields that range from organic electronics to sensors and bioapplications.

Block copolymer-based nanoproducts including particles, fibers and films show promise in high-end applications including nanotemplating, nanolithography, and nanoporous membranes due to their advantageous selfassembled structure. However, few studies probe the nanofabrication process in detail and monitor the concomitant self-assembled structural transitions. Herein, time-resolved small-angle X-ray scattering (SAXS) is exploited to follow such nanostructural changes. Evaporation-induced casting, electrospraying or electrospinning, followed by a final solvent vapor annealing step, have been used to create a series of nanoproducts with reversibly tunable morphologies from a model block copolymer, polystyrene-b-poly(ethylene-co-butylene)-bpolystyrene (SEBS). During evaporation-induced casting, which is considered as an unconfined system, a selective (co)solvent system composed of tetrahydrofuran (THF) and dimethylformamide (DMF) can lead to the formation of various SEBS structures. For DMF-based unconfined systems, the final SEBS lamellar structures were found to be different from the structure formed from THF only, demonstrating the critical role of solvent selection in evaporation-induced casting. The comparison of SEBS electrospun fibers reveals the unique and complex self-assembled structural transition occurring in a confined system. Time-resolved SAXS studies of our model triblock copolymer provide guidelines for a more general approach to access various nanostructures from self-assembling block copolymers.

Controlling the dispersibility of nanocrystalline inorganic quantum dots (QDs) within organic semiconductor (OSC):QD nanocomposite films is critical for a wide range of optoelectronic devices. This work demonstrates how small changes to the OSC host molecule can have a dramatic detrimental effect on QD dispersibility within the host organic semiconductor matrix as quantified by grazing incidence X-ray scattering. It is commonplace to modify QD surface chemistry to enhance QD dispersibility within an OSC host. Here, an alternative route toward optimizing QD dispersibilities is demonstrated, which dramatically improves QD dispersibilities through blending two different OSCs to form a fully mixed OSC matrix phase.

We report the synthesis of novel terpene-based monomers: nopinyl acrylate and methacrylate, from naturally abundant beta-pinene. A very high Tg value was observed for poly(nopinyl methacrylate) when synthesised by free radical polymerisation, and well-defined polymers have been produced via RAFT polymerisation. This exciting new high Tg material shows promise as a hard block in thermoplastic elastomers. ABA triblock copolymers have been synthesised which also incorporate a low Tg renewable soft block, poly(tetrahydrogeraniol methacrylate), using a divergent, difunctional RAFT polymerisation method. Initial phase separation behaviour and adhesive properties have been investigated to highlight the potential of these copolymer materials as renewably sourced thermoplastic elastomers.

Singlet fission (SF) is a promising strategy to overcome thermalization losses and enhance the efficiency of single junction photovoltaics (PVs). The development of this field has been strongly material-limited, with a paucity of materials able to undergo SF. Rarer still are examples that can produce excitons of sufficient energy to be coupled to silicon PVs (>1.1 eV). Herein, we examine a series of a short-chain polyene, dithienohexatriene (DTH), with tailored material properties and triplet (T1) energy levels greater than 1.1 eV. We find that these highly soluble materials can be easily spin-cast to create thin films of high crystallinity that exhibit ultrafast singlet fission with near perfect triplet yields of up to 192%. We believe that these materials are the first solution-processable singlet fission materials with quantitative triplet formation and energy levels appropriate for use in conjunction with silicon PVs.