Solid-state spin qubits offer a promising route toward scalable quantum technologies. Here we demonstrate that, despites of a nuclear-spin-rich host of halide double perovskites (HDPs), transition-metal centers (Cr³⁺ and Fe³⁺ ions) are a good candidate for spin qubits exhibiting long-lived electron spin coherence with T₂ = 29.5 µs and 21.2 µs at 4 K, respectively. Notably, spin localization facilitates a well-defined electron-nuclear (e-N) spin rotation between the electron spin and the neighboring nuclear spins of ^35,37Cl and ¹³³Cs. The resulting e-N spin cluster is readily beneficial for a target nuclear-spin sensing. For the Cr³⁺ spin centers, the optical transitions associated with Cr³⁺ spin centers is spin-selective thereby paving a way for optical addressing of spins. Our findings from these spin ensemble studies establish HDPs as a new promising platform for creating solid-state spin qubits using simple and inexpensive solution-based single crystal growth methods, broadening material applications of halide perovskites.

An efficient oxygen reduction reaction (ORR) is crucial for deoxygenation electrolyzers. However, the use of metal catalysts in electrolyzer designs is challenging due to their high cost, catalyst dissolution, and susceptibility to poisoning. Conductive polymers have emerged as a promising new class of metal-free catalysts for ORR, combining electron conductivity and a lack of an insulating oxidation layer. In this study, a new n-type polymer is explored, poly(benzimidazobenzophenanthroline) (BBL), as an ORR catalyst to enhance deoxygenation efficiency in carbon-based electrolyzers. Electrocatalytic studies show that BBL film improves ORR kinetics via a four-electron pathway with a mass activity of the order of 100 A g-1. A low-voltage electrolyzer is constructed and tested using BBL-coated carbon fiber paper (CFP) as the cathode for ORR and CFP as the anode to drive the oxidation of catechol as a compensating faradaic reaction to facilitate ORR. The deoxygenation electrolyzer with a drop-cast BBL cathode achieves fast deoxygenation kinetics, reaching below 0.1 mg L-1 DO in salty solution with 0.001 m catechol. The findings introduce a new approach to deoxygenating thermal fluids by employing an ORR polymer catalyst and a compensating redox additive (RA) in water.

Reducing heterointerface nonradiative recombination is a key challenge for realizing highly efficient perovskite solar cells (PSCs). Motivated by this, a facile strategy is developed via interfacial energetics reversal to functionalize perovskite heterointerface. A surfactant molecule, trichloro[3-(pentafluorophenyl)propyl]silane (TPFS) reverses perovskite surface energetics from intrinsic n-type to p-type, evidently demonstrated by ultraviolet and inverse photoelectron spectroscopies. The reconstructed perovskite surface energetics match well with the upper deposited hole transport layer, realizing an exquisite energy level alignment for accelerating hole extraction across the heterointerface. Meanwhile, TPFS further diminishes surface defect density. As a result, this cooperative strategy leads to greatly minimized nonradiative recombination. PSCs achieve an impressive power conversion efficiency of 25.9% with excellent reproducibility, and a nonradiative recombination-induced qVoc loss of only 57 meV, which is the smallest reported to date in n-i-p structured PSCs.

Cellulose-based materials can be classified as non-conventional luminogens that produce photoluminescence (PL) in the visible range due to specific intermolecular arrangements. Usually such an arrangement is referred to as clusterization. Here, we demonstrate the importance of intramolecular arrangement of ethyl cellulose and bacterial cellulose that demonstrate tunable photoluminescence with multiexponent decay. We show that the observed emission is due to a n-pi* electronic transition of carbonyl groups, whose emission intensity depends on the form of the sample preparation, either the powder-form or spin-coated films, displaying different density of the emitting regions on the microscale. Particularly, it is shown that PL emission is produced from disordered amorphous regions rather than from crystalline ones. We show that the emission is also promoted by mechanical stress applied to the sample that is suggested to facilitate formation of hydrogen-bonded carbonyl groups. The observed stress-assisted emission opens up the potential perspective of using this phenomenon in printed photonic devices.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a benchmark hole-transporting (p-type) polymer that finds applications in diverse electronic devices. Most of its success is due to its facile synthesis in water, exceptional processability from aqueous solutions, and outstanding electrical performance in ambient. Applications in fields like (opto-)electronics, bioelectronics, and energy harvesting/storage devices often necessitate the complementary use of both p-type and n-type (electron-transporting) materials. However, the availability of n-type materials amenable to water-based polymerization and processing remains limited. Herein, we present a novel synthesis method enabling direct polymerization in water, yielding a highly conductive, water-processable n-type conjugated polymer, namely, poly[(2,2 '-(2,5-dihydroxy-1,4-phenylene)diacetic acid)-stat-3,7-dihydrobenzo[1,2-b:4,5-b ']difuran-2,6-dione] (PDADF), with remarkable electrical conductivity as high as 66 S cm(-1), ranking among the highest for n-type polymers processed using green solvents. The new n-type polymer PDADF also exhibits outstanding stability, maintaining 90% of its initial conductivity after 146 days of storage in air. Our synthetic approach, along with the novel polymer it yields, promises significant advancements for the sustainable development of organic electronic materials and devices.

Photoelectrochemical (PEC) water splitting is a promising approach to directly convert solar energy to renewable and storable hydrogen. However, the very low photovoltage and serious corrosion of semiconductor photoelectrodes in strongly acidic or alkaline electrolytes needed for water splitting severely impede the practical application of this technology. In this work, we demonstrate a facile approach to fabricate a high-photovoltage, stable photoanode by depositing Ni(OH)(2) cocatalyst on cubic silicon carbide (3C-SiC), followed by aging in 1.0 M NaOH at room temperature for 40 h without applying electrochemical bias. The aged 3C-SiC/Ni(OH)(2) photoanode achieves a record-high photovoltage of 1.10 V, an ultralow onset potential of 0.10 V vs the reversible hydrogen electrode, and enhanced stability for PEC water splitting in the strongly alkaline solution (pH = 13.6). This aged photoanode also exhibits excellent in-air stability, demonstrating identical PEC water-splitting performance for more than 400 days. We find that the aged Ni(OH)2 dramatically promotes the hole transport at the photoanode/electrolyte interface, thus significantly enhancing the photovoltage and overall PEC performance. Furthermore, the oxygen evolution reaction (OER) activity and the phase transitions of the Ni(OH)(2) electrocatalyst before and after aging are systematically investigated. We find that the aging process is critical for the formation of the relatively stable and highly active Fe-doped beta-NiOOH, which accounts for the enhanced OER activity and stability of the PEC water splitting. This work provides a simple and effective approach to fabricate high-photovoltage and stable photoanodes, bringing new premise toward solar fuel development.

Herein, a binary cathode interface layer (CIL) strategy based on the industrial solvent fractionated LignoBoost kraft lignin (KL) is adopted for fabrication of organic solar cells (OSCs). The uniformly distributed phenol moieties in KL enable it to easily form hydrogen bonds with commonly used CIL materials, i.e., bathocuproine (BCP) and PFN-Br, resulting in binary CILs with tunable work function (WF). This work shows that the binary CILs work well in OSCs with large KL ratio compatibility, exhibiting equivalent or even higher efficiency to the traditional CILs in state of art OSCs. In addition, the combination of KL and BCP significantly enhanced OSC stability, owing to KL blocking the reaction between BCP and nonfullerene acceptors (NFAs). This work provides a simple and effective way to achieve high-efficient OSCs with better stability and sustainability by using wood-based materials. This work introduces industrial solvent fractionated LignoBoost kraft lignin (KL) in highly efficient organic solar cells (OSCs) by binary cathode interface layer (CIL) strategy, which can significantly improve the stability of both binary and ternary photoactive layer (PAL) OSC, owing to the passivation of diffusion and reaction between bathocuproine (BCP) and nonfullerene acceptors (NFAs). The results combine sustainable wood-based material with classic interface materials in advance NFA-OSCs.image

A new approach to control the n-doping reaction of organic semiconductors is reported using surface-functionalized gold nanoparticles (f-AuNPs) with alkylthiols acting as the catalyst only upon mild thermal activation. To demonstrate the versatility of this methodology, the reaction of the n-type dopant precursor N-DMBI-H with several molecular and polymeric semiconductors at different temperatures with/without f-AuNPs, vis-a-vis the unfunctionalized catalyst AuNPs, was investigated by spectroscopic, morphological, charge transport, and kinetic measurements as well as, computationally, the thermodynamic of catalyst activation. The combined experimental and theoretical data demonstrate that while f-AuNPs is inactive at room temperature both in solution and in the solid state, catalyst activation occurs rapidly at mild temperatures (similar to 70 degrees C) and the doping reaction completes in few seconds affording large electrical conductivities (similar to 10-140 S cm(-1)). The implementation of this methodology enables the use of semiconductor+dopant+catalyst solutions and will broaden the use of the corresponding n-doped films in opto-electronic devices such as thin-film transistors, electrochemical transistors, solar cells, and thermoelectrics well as guide the design of new catalysts.

Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics, especially utilizing organic photovoltaics (OPVs). Combined liquid- and solid-state processing, such as printing and lamination used in industry for developing indoor OPVs, also provides a new opportunity to investigate the device structure, which is otherwise hardly possible based on the conventional approach due to solvent orthogonality. This study investigates the impact of fullerene-based acceptor interlayer on the performance of conjugated polymer-fullerene-based laminated OPVs for indoor applications. We observe open-circuit voltage (V-OC) loss across the interface despite this arrangement being presumed to be ideal for optimal device performance. Incorporating insulating organic components such as polyethyleneimine (PEI) or polystyrene (PS) into fullerene interlayers decreases the work function of the cathode, leading to better energy level alignment with the active layer (AL) and reducing the V-OC loss across the interface. Neutron reflectivity studies further uncover two different mechanisms behind the V-OC increase upon the incorporation of these insulating organic components. The self-organized PEI layer could hinder the transfer of holes from the AL to the acceptor interlayer, while the gradient distribution of the PS-incorporated fullerene interlayer eliminates the thermalization losses. This work highlights the importance of structural dynamics near the extraction interfaces in OPVs and provides experimental demonstrations of interface investigation between solution-processed cathodic fullerene layer and bulk heterojunction AL.

Carbon dots (CDs) are recognized as promising fluorescent nanomaterials with bright emission and large variations of photoluminescence quantum yield (PLQY). However, there is still no unique approach for explanation of mechanisms and recipes for synthetic procedures/chemical composition of CDs responsible for the enhancement of PLQY. Here, we compare photophysical behavior and PLQY of two types of CDs synthesized by different routes, leading to the different extent of oxidation and composition. The first type of CDs represents a conjugated carbon system oxidized by F, N and O heteroatoms, whereas the second type represents a non-conjugated carbon system oxidized by oxygen. Photophysical data, photoemission spectroscopy and microscopy data yield the suggestion that in the first case, a structure with a distinct carbon core and highly oxidized electron-accepting shell is formed. This leads to the excitonic type non-tunable emission with single-exponent decay and high PLQY with a strong dependence on the solvent polarity, being as high as 93% in dioxane and as low as 30% in aqueous medium, but which is vulnerable to photobleaching. In the second case, the oxidized CDs do not indicate a clear core-shell structure and show poor solvatochromism, negligible photobleaching, low PLQY varying in the range of 0.7-2.3% depending on the solvent used, and tunable emission with multi-exponent decay, which can be described by the model of multiple emission centers acting through a clustering-triggered emission mechanism. The obtained results lead to a strategy that allows one to design carbon nanomaterials with principally different PLQYs that differ by orders of magnitude.