Asymmetric Π-Bridge Engineering Enables High-Permittivity Benzo[1,2-B:4,5-b']Difuran-Conjugated Polymer for Efficient Organic Solar Cells.

Organic solar cells (OSCs) exhibit complex charge dynamics, which are closely correlated with the dielectric constant (ɛr ) of photovoltaic materials. In this work, a series of novel conjugated copolymers based on benzo[1,2-b:4,5-b']difuran (BDF) and benzotriazole (BTz) is designed and synthesized, which differ by the nature of π-bridge from one another. The PBDF-TF-BTz with asymmetric furan and thiophene π-bridge demonstrates a larger ɛr of 4.22 than PBDF-dT-BTz with symmetric thiophene π-bridge (3.15) and PBDF-dF-BTz with symmetric furan π-bridge (3.90). The PBDF-TF-BTz also offers more favorable molecular packing and appropriate miscibility with non-fullerene acceptor Y6 than its counterparts. The corresponding PBDF-TF-BTz:Y6 OSCs display efficient exciton dissociation, fast charge transport and collection, and reduced charge recombination, eventually leading to a power conversion efficiency of 17.01%. When introducing a fullerene derivative (PCBO-12) as a third component, the PBDF-TF-BTz:Y6:PCBO-12 OSCs yield a remarkable FF of 80.11% with a high efficiency of 18.10%, the highest value among all reported BDF-polymer-based OSCs. This work provides an effective approach to developing high-permittivity photovoltaic materials, showcasing PBDF-TF-BTz as a promising polymer donor for constructing high-performance OSCs.

Holistically Optimizing Charge Carrier Dynamics Enables High-Performance Dye-Sensitized Solar Cells and Photodetectors.

Charge carrier events across organic electronics are ubiquitous, and the derived optimization plays a crucial effect on improving the performance of organic electronics. Herein, a two-dimensional material (Ti3C2Tx) is incorporated into titanium dioxide (TiO2) to impart the Ti3C2Tx/TiO2 hybrid film enriched hydroxy group distribution, defect-negligible surface, upshifted work function, and enhanced conductivity yet electron mobility versus the pristine TiO2 film. Therefore, intensified photon-harvesting ability, reduced charge carrier recombination, and efficient charge carrier collection are realized for dye-sensitized solar cells (DSSCs) based on the Ti3C2Tx/TiO2 hybrid photoanode relative to control ones. Consequently, the modified DSSCs based on Z907 deliver superior efficiencies of 10.39 and 29.68% under 100 mW/cm2 illumination and ∼1.9 mW/cm2 dim light, respectively, being the highest values of Z907-based DSSCs. However, control devices only obtain lower efficiencies of 8.06 and 23.91% when undergoing the abovementioned illumination. On the other hand, the self-powered homologous photodetectors with the hybrid film as an electron-transporting layer present enhanced detectivity (1.69 × 1011 Jones) and a shortened responsivity of 0.26 s versus that of control ones (1.39 × 1011 Jones and 0.35 s). Our work implies that the Ti3C2Tx/TiO2 hybrid film features high potential for improving the performance of organic electronics for its effect of holistically optimizing charge carrier dynamics.

Multifunctional Two-Dimensional Benzodifuran-Based Polymer for Eco-Friendly Perovskite Solar Cells Featuring High Stability.

Perovskite solar cells (PSCs) have been regarded as an exceptional renewable energy conversion technology due to their rapidly increasing photovoltaic efficiency, while their practical application is highly retarded by their intrinsic instability and potential lead ion leakage. Here, a two-dimensional (2D) π-conjugated benzodifuran-based polymer, PBDFP-Bz, is adopted to modify the perovskite film. Note that PBDFP-Bz could neutralize surface defects, fine-tune interfacial energetics, and hamper moisture ingression into the perovskite film. Therefore, high-quality perovskite films featuring reduced trap state density and enhanced moisture tolerance could be obtained after modification via PBDFP-Bz. Consequently, PBDFP-Bz-modified devices deliver a higher efficiency of 21.73% versus 19.55% of control ones. Meanwhile, PBDFP-Bz-modified devices can preserve 82.7 and 90.8% of their initial efficiency under continuous heating at 85 °C or light soaking for 500 h. However, the corresponding retained values of control devices are only 56.4 and 70.2%, respectively. Moreover, PBDFP-Bz can effectively prevent the leakage of lead ions in modified devices relative to control ones. This work not only reveals that PBDFP-Bz features high potential for fabricating high-performance and robust PSCs but also indicates that 2D π-conjugated benzodifuran-based polymers can endow PSCs with great security for sustainable development without the concern of lead ion leakage.

Maize starch derived boron doped carbon spheres via facile solvothermal route as the photoluminescence sensor for determination of pH and Cr(VI).

In this work, a kind of boron doped carbon spheres (B-CSs) was successfully synthesized utilizing maize starch as carbon source and boric acid as dopant via facile solvothermal method. The chemical structure of the prepared B-CSs was systemically investigated by TEM, FT-IR, XRD, XPS and EDS. The synthesized B-CSs feature spherical structure with average size of ∼254 nm and exhibit strong photoluminescence (PL) with maximum emission at a wavelength of ∼453 nm under irradiation at 350 nm, leading to a quantum yield of 6.2%. Furthermore, the aqueous pH and Cr(VI) has a significantly various impact on the PL intensity of B-CSs, which can be flexibly utilized as the PL sensor for detection aqueous pH and Cr(VI) in aqueous. Particularly, the B-CSs have a desirable sensitivity and selectivity for detection of Cr(VI) with a low detection limit of ∼0.34µmol l-1. Conclusively, our work provides a novel and dual-functional fluorescent sensor for detection of the pH and toxic metal ions in water environment.

Starch phosphate carbamate hydrogel based slow-release urea formulation with good water retentivity.

In this work, a novel starch phosphate carbamate hydrogel (SPC-Hydrogel) and its corresponding urea hydrogel (SPCU-Hydrogel) slow-release fertilizer (SRF) were prepared by one-step free radical copolymerization of SPC and acrylamide (AM) without and with urea addition. A series of characterization measurements including FTIR, XRD, EDS, XPS are utilized to confirm the successful formation of the SPC-Hydrogel. The SEM shows SPC-Hydrogel has a porous three-dimensional network architecture. Furthermore, SPC-Hydrogel matrix exhibits superior water absorbency achieving 80.2 g/g than that (70.5 g/g) of the native starch hydrogel (NS-Hydrogel) and desirable water retention capacity in soil with a weight loss of only 48% for 13 days. Compared with pure urea and NS based urea hydrogel (NSU-Hydrogel), the SPCU-Hydrogel releases 50.3% for 15 h, achieving an almost complete release more than 25 h in aqueous phase. While only 46.6% of urea is released in 20 days which extends about 30 days in soil column assays. The maize seedlings growth assays also present an intuitive evaluation on the prominent soil water holding and plant growth promotion role of SPCU-Hydrogel. In conclusion, the present work has demonstrated a novel strategy via preparing biomass hydrogel SRF to enhance the utilization effectiveness of fertilizer and retain soil humidity.