Journal of Materials Chemistry C最新文献

Organic solar cells (OSCs) have attracted impressive interest due to their advantages of flexibility, light weight, non-toxicity, and transparency. However, it is not feasible to explore the gigantic chemical space purely through experimental approaches. Herein, a framework based on deep learning models was developed to establish a direct relationship between the molecular structure and device efficiency. Eight graph neural network models were applied to a newly established dataset consisting of 1060 realistic organic donor/acceptor (D/A) pairs to predict the power conversion efficiency (PCE). It is notable that the data fidelity and unity were enhanced by manually collecting reported upper limit values. Among these models, the graph attention network (GAT) model exhibited the best performance (r = 0.74, RMSE = 2.63), comparable to previous studies but with significantly lower computational costs. The deep learning models were then employed to predict and screen a developed dataset, consisting of 45 430 possible donor–acceptor combinations, in which the donors and acceptors were sourced from cases with PCE values exceeding 10%. The average predicted PCE range is from 3.61 to 17.43%, and only 2320 (5.1%) D/A pairs were predicted to achieve PCE values above 15%, indicating the importance of theoretical calculations. Several pairs were identified with high PCE values, which were reported in the literature but not in the dataset used in this work. Furthermore, electronic structure calculations were performed on potential candidates to gain insights into the materials, further validating the reliability of the predictions. Our work then provides an efficient workflow to accelerate high-throughput screening of OSC materials, aiding in the development of highly efficient OSCs.

Two-dimensional polymers (2DPs) are emerging as promising charge-trapping layers for organic non-volatile memories (ONVMs), offering advantages such as tunable structures, flexibility, and light weight. Despite extensive research on the backbones of 2DPs, the influence of side chains remains underexplored. In this study, we address this gap by synthesizing four 2DP variants with identical backbones but different side chains. Among them, poly-TT, featuring hexoxy side chains, exhibits the best memory performance, achieving a memory window exceeding 30 V and exceptional stability. Photoluminescence (PL) and temperature-dependent PL spectroscopy reveal that the hexoxy side chains enhance charge transfer efficiency and exciton separation in ONVMs. These findings deepen our understanding of the structure–property relationships in 2DPs and provide new strategies for designing high-performance, durable, flexible memory devices.

SrAl₂O₄:Eu²⁺,Nd³⁺ is a well-known persistent phosphor due to its outstanding green persistent luminescence performance. In SrAl₂O₄:Eu²⁺,Nd³⁺, the Nd³⁺ ions are commonly considered as an auxiliary activator, even though they themselves are an excellent near-infrared luminescence center at 900–1400 nm. Moreover, though the SrAl₂O₄:Eu²⁺,Nd³⁺ phosphor was known to be effectively charged by ultraviolet and white light, the charging effectiveness of different wavelengths was never studied. Here, we revisit the SrAl₂O₄:Eu²⁺,Nd³⁺ persistent phosphor and report some new spectroscopic phenomena. Besides the long-lasting green persistent luminescence of Eu²⁺ (>20 h), the SrAl₂O₄:Eu²⁺,Nd³⁺ persistent phosphor also simultaneously emits long near-infrared persistent luminescence of Nd³⁺ (>4 h), due to efficient persistent energy transfer from Eu²⁺ to Nd³⁺. We acquire the first-ever persistent luminescence excitation spectrum on SrAl₂O₄:Eu²⁺,Nd³⁺ and surprisingly find that 365 nm ultraviolet light, which is often used to charge the SrAl₂O₄:Eu²⁺,Nd³⁺ phosphor, is actually least effective within the 250–470 nm wavelength range in producing persistent luminescence. Blue light at around 440 nm is the most suitable light to charge the phosphor. The charging mechanisms of different excitation wavelengths are studied through thermoluminescence measurements. In vitro bioimaging experiments suggest that the SrAl₂O₄:Eu²⁺,Nd³⁺ persistent phosphor is a promising near-infrared imaging probe for high-contrast deep-tissue bioimaging.

Multiresonance thermally activated delayed fluorescence (MR-TADF) technology has garnered significant attention because MR-TADF emitters enable both high efficiency and high color purity, making them ideal for next-generation high-resolution displays. However, the lifetime of MR-TADF-based OLEDs is considerably lower than that of phosphorescent and conventional TADF counterparts. To address this challenge, we focused on (i) a phosphor-sensitized hyper-OLED system to improve both the efficiency and the lifetime, and (ii) the interface between the hole-transport layer (HTL) and the emission layer (EML). This interface was found to be crucial for achieving both high efficiency and long operational lifetimes in MR-TADF-based hyper-OLEDs. By employing an HTL with a deep ionization potential, which prevents hole accumulation at the HTL/EML interface and direct carrier trapping on the MR-TADF emitter, we successfully extended the lifetime of phosphor-sensitized hyper-OLEDs based on MR-TADF emitters. Consequently, we realized green hyper-OLEDs with CIE coordinates of (0.31, 0.66), an external quantum efficiency of 28.1%, a power efficiency of 159.9 lm W⁻¹, and operational lifetimes at 95/90% of the initial luminance of 1000 cd m⁻² (LT_95/90) of over 600/2400 hours at a high brightness of 1000 cd m⁻². These performances are among the best reported in scientific literature.

Owing to their high strength and high toughness, ionically conductive elastomers have wide application prospects in artificial muscle materials, lithium-ion batteries and other fields. In this work, on the basis of a polymerizable deep eutectic solvent (DES) prepared from acrylic acid (AA) and choline chloride (ChCl) and N-(2-hydroxyethyl) acrylamide (HEAA) monomers, a high-strength and high-toughness ionic conductive elastomer P(DES–HEAA) was successfully prepared via one-step photopolymerization without the use of any chemical crosslinking agents. The elastomer not only has excellent mechanical properties (tensile strength: 15.59 MPa, tensile strain: 521%, Young's modulus: 652.3 MPa, toughness: 56.2 MJ m⁻³) but also has high transparency, satisfactory conductivity, good shape memory and excellent anticutting and wear resistance. Owing to the simple and fast preparation process (light irradiation for 10 min) and the excellent properties of the obtained elastomers, this study provides a novel and effective strategy for the development of high-strength, high-toughness, and damage-resistant ionic conductive elastomers.

The balance between ion implantation and carrier transport is a critical factor in achieving high-performance polymer electrochemical transistors (PECTs). While the crystallinity of polymer films typically enhances the charge transport capacity of these devices, the orderly packed chains impede the injection of ions. In this study, poly(3-hexylthiophene) (P3HT) nanowires were incorporated into PECTs to address this issue. The μC_v value (μ: charge mobility, C_v: volumetric capacitance; the product μC_v has been proposed as a figure of merit for OECT materials) of the films with embedded nanowires (WN) is approximately three times that of the films without nanowires (W/O N), and the subthreshold swing of the WN devices is also lower than that of the W/O N devices. These findings indicate the superior ion doping property of the WN devices. The time evolution of the absorption difference spectra for the films demonstrates that the ions preferentially dope the J-aggregate regions in the WN films, which correspond to the nanowires. The results suggest that the nanowires enhance ion doping in the WN films, likely due to their large specific surface area. This work demonstrates a feasible strategy to effectively improving ion implantation while maintaining charge mobility by introducing polymer crystallization into PECT devices.

Among organic small molecules characterized by multifaceted behaviour, triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine, TT, having a triazinic central ring with three annelated imidazoles, represents a fascinating but still underinvestigated scaffold endowed with intriguing luminescence and coordination properties. Here we comprehensively gather studies, mainly conducted by our research group, on several fully organic or hybrid inorganic–organic TTs revealing their AIE, RTP, mechanochromic and excitation dependent photoluminescence behaviours. Preliminary applications of TTs in sensing and bio-medicine are also reported, opening avenues for further studies in these fields and widening the potentiality of TT and its derivatives. On the whole, the results shown here clearly demonstrate that cyclic triimidazole can be rightfully included in the toolbox of powerful scaffolds inspiring the preparation of multifunctional molecular materials.

Wide-bandgap quantum dots (QDs) have recognized as the third generation of low-dimensional semiconductors with reliable optical response, outstanding stability and biocompatibility for long-term biosensing in health care applications, especially in extreme environments. However, the applicable scenarios are limited, because optical switching over a large span from the wide bandgap (deep UV region) to the visible region is challenging due to the stable framework and the high breakdown difficulty. In this work, we adopted a facile protonation/deprotonation treatment process, which is suitable for different biogenic environments, to modulate the one-photon and two-photon fluorescence of wide-bandgap QDs. Two fluorescent centers are coordinative to control one-photon emission from deep blue (410 nm) to yellow (585 nm) emission with a wide large-span modulation, superior to most reports under different acid–base environments. The electron transition between electron-donating amine (–NH₂) groups and H⁺ (–OH) changes the degree of nonradiative transition, narrowing the breadth of the full width at half maximum (FWHM) by 34.4%. Moreover, our QDs exhibit two-photon fluorescence at 710 nm, which have never reported before for wide-bandgap nitrides. It shows pH-independent two-photon fluorescence because of the intrinsic electron–phonon coupling of the π-conjugated structure. This work introduces a simple design strategy to realize fluorescence control over a large span in wide-bandgap nanomaterials, enabling distensible applications in biological health and pH related linear or nonlinear optical fields.

Through ion substitution, a new Sr₄GaNbO₈ perovskite structure with the same structure as Sr₄AlNbO₈ was successfully prepared, and a series of Sr₄GaNbO₈:Mn⁴⁺ phosphors were prepared using a high-temperature solid-state reaction method, after which the related concentration quenching mechanism was demonstrated to be electric dipole–dipole interaction. Furthermore, their thermal quenching characteristics were studied in detail over a temperature range from 303 K to 393 K. Based on obvious quenching of temperature-dependent decay curves, luminescence lifetime thermometers were further designed and developed. It was ultimately found that the maximum relative temperature sensitivity, absolute temperature sensitivity value and the minimum temperature uncertainty were 3.34% K⁻¹ at 393 K, 4.15 μs K⁻¹ at 303 K and 0.09 K at 393 K, respectively. Moreover, Sr₄GaNbO₈:Mn⁴⁺ maintained high stability with a maximum repeatability of 0.998 after multiple cycling tests. Multiple lifetime tests at the same temperature (333 K) revealed that the Sr₄GaNbO₈:Mn⁴⁺ phosphor exhibited strong stability. These results indicate that as-prepared Sr₄GaNbO₈:Mn⁴⁺ materials have significant potential for application in lifetime thermometers.

In this study, single-walled carbon nanotube (SWCNT)/Cu nanocomposites were systematically synthesized from oxidized SWCNTs and Cu formate via photothermal heating. The incorporation of Cu nanoparticles (Cu NPs) on the surface of SWCNTs, especially for a weight ratio of 1 : 20, enhanced the electrical conductivity of the SWCNTs, resulting in a resistivity of 80 μΩ cm. In mechanical bending tests, the nanocomposites showed excellent performance stability for various bending angles, which indicated their suitability for use in flexible electronics. The mechanical flexibility of the SWCNTs significantly delayed crack propagation in Cu NPs, resulting in the structural integrity of the composites being maintained. Furthermore, we measured the electromagnetic interference (EMI) shielding effectiveness of the composites, and its values for the 1 : 5, 1 : 10, and 1 : 20 wt% composites reached 25.5–33.6, 39.9–45.6, and 56.2–60.3 dB, respectively. Thus, the effectiveness increased rapidly with an increase in the Cu content. The feasibility of using the composites as EMI shielding materials was further supported by received signal strength indication (RSSI) measurements for commercial Bluetooth signals. Overall, these findings highlight the high potential of SWCNT/Cu composites for use as conductive materials in advanced flexible electronics.