Publications

Abstract In this study, a series of donor–acceptor–donor (D‐A‐D) type small molecules based on the fluorene and diphenylethenyl enamine units, which are distinguished by different acceptors, as holetransporting materials (HTMs) for perovskite solar cells is presented. The incorporation of the malononitrile acceptor units is found to be beneficial for not only carrier transportation but also defects passivation via Pb–N interactions. The highest power conversion efficiency of over 22% is achieved on cells based on V1359, which is higher than that of spiro‐OMeTAD under identical conditions. This st shows that HTMs prepared via simplified synthetic routes are not only a low‐cost alternative to spiro‐OMeTAD but also outperform in efficiency and stability state‐of‐art materials obtained via expensive cross‐coupling methods.

A NiMoS₄ nanoarray on Ti mesh (NiMoS₄/Ti), developed <italic>via</italic> topotactic hydrothermal conversion from its Ni(OH)₂ nanoarray (Ni(OH)₂/Ti), drives hydrogen-evolution current densities of 10 and 50 mA cm⁻² at overpotentials of 194 and 263 mV in 0.1 M KOH, respectively.

The ambient electrocatalytic N₂ reduction reaction (NRR) enabled by TiO₂ has attracted extensive recent attention. Previous studies suggest the formation of Ti³⁺ in TiO₂ can significantly improve the NRR activity, but it still remains unclear what kinds of Ti³⁺ are effective. Herein, it is demonstrated that mixed-valent Cu acts as an effective dopant to modulate the oxygen vacancy (V_O ) concentration and Ti³⁺ formation, which markedly improves the electrocatalytic NRR performance. In 0.5 m LiClO₄ , this electrocatalyst attains a high Faradic efficiency of 21.99% and a large NH₃ yield of 21.31 µg h^-1 mg_cat. ^-1 at -0.55 V vs reversible hydrogen electrode, which even surpasses most reported Ti-based NRR electrocatalysts. Using density function theory calculations, it is evidenced that mixed-valent Cu ions modulate the TiO₂ (101) surface with multiple oxygen vacancies, which is beneficial for generating different Ti³⁺ 3d¹ defect states localized below the Fermi energy. N₂ activation and adsorption are effectively strengthened when Ti³⁺ 3d¹ defect states present the splitting of e_g and t_2g orbitals, which can be modulated by its coordination structure. The synergistic roles of the three ion pairs formed by the V_O defect, including Cu¹⁺ -Ti⁴⁺ , Ti³⁺ -Ti⁴⁺ and Ti³⁺ -Ti³⁺ , are together responsible for the enhanced NRR performance.

The use of weak bases as accelerators for reversible addition-fragmentation chain transfer radical polymerization (RAFT) of isoprene is demonstrated. Adding weak bases to RAFT polymerization, the conversion of isoprene could be greatly improved and reach about 50%. The effects of weak base on the polymerization were investigated. The living and controlled character of the RAFT polymerization of isoprene was confirmed by the linear increase in molecular weight with monomer conversion, the narrow molecular weight distribution and synthesis of polyisoprene-block-polystyrene (PIP-b-PS) block copolymer. The results of 1HNMR spectroscopy show that the structure of polyisoprene (PIP) with weak bases as accelerators was the same to the structure of PIP without any accelerator. The data presented here prove that weak bases are an efficient accelerator to inhibit Diels-Alder reaction of isoprene in the RAFT polymerization.

Polyethersulfone (PES) has been widely used in membrane technology and used to purify water in water treatments application or as a dialyzer to purify blood in hemodialysis. In this work, PES was chemically modified by separately grafting two biomolecules, 4‐aminobenzenesulfonamide (ABS), and 4‐amino‐N‐(5‐methylisoxazol‐3‐yl)benzenesulfonamide (AMBS), on PES backbone, and these modified membranes were blended to unmodified PES, in 1:1 ratio, in order to obtain PES‐b‐PES‐ABS and PES‐b‐PES‐AMBS membranes. The first aim of this study is to measure the anticoagulant properties of the modified membrane by measuring the activated partial thromboplastin time (APTT) and prothrombin time (PT). The second aim of the study is to evaluate the antifouling properties of the modified PES membranes by examining its antimicrobial activity against two Gram‐negative bacteria, which are Pseudomonas aeruginosa ( P. aeruginosa ) and Escherichia coli ( E. coli ); two Gram‐positive bacteria, which are Bacillus subtilis ( B. subtilis ) and Staphylococcus aureus ( S. aureus ); and a fungus, which is Candida albicans ( C. albicans ). The results showed that grafting of ABS and AMBS improved overall the hydrophilicity properties of the modified PES membranes. PES‐b‐PES‐ABS membranes showed better anticoagulant properties with 13 seconds for PT and 38 seconds for APPT, in comparison with the control sample (pure plasma), which showed 12 seconds for PT and 30 seconds for APPT. For antimicrobial tests, both PES‐b‐PES‐ABS and PES‐b‐PES‐AMBS membranes did not show any antibacterial activity, but when zinc oxide (ZnO) nanoparticles were added to the modified PES membranes in concentrations between 3% to 5% w /w, PES‐b‐PES‐ABS‐ZnO (M‐4 and M‐5), and PES‐b‐PES‐AMBS‐ZnO (M‐8 and M‐9) nanocomposite membranes showed antibacterial activity against P. aeruginosa and S. aureus .

Three donor–π‐bridge–acceptor (D–π–A)‐type organic small molecules coded CI‐B1, CI‐B2, and CI‐B3 are designed, synthesized, and used as dopant‐free hole transporting materials (HTMs) for perovskite solar cells (PSCs). The strong electron‐donating triazatruxene central core (D), terthiophene conjugated arms (π), and three different strong electron‐accepting units (A) provide high intramolecular charge transfer nature and eliminate the need of dopants during the fabrication of PSCs. HTMs are investigated to understand the effect of terminal functional groups on the PSC performance. Interestingly, due to the change of end‐capping, three different organizations of self‐assembly with π–π stacking are observed in the solid thin films. Dopant‐free CI‐B1, CI‐B2, CI‐B3, and spiro‐OMeTAD with dopants are used with triple cation perovskite composition Cs 0.1 (MA 0.15 FA 0.85 ) 0.9 Pb(I 0.85 Br 0.15 ) 3 (MA: CH 3 NH 3 + , FA: NHCHNH 3 + ) in n‐i‐p architecture. The cells prepared with CI‐B3 not only exhibits a comparable power conversion efficiency (PCE) of 17.54% to the state‐of‐art of spiro‐OMeTAD with dopants (18.02%), but also demonstrates improved long‐term stability, maintaining 88% of its original PCE after 1000 h of illumination. The superior photovoltaic performance, synthetic simplicity, dopant‐free nature, high durability, and edge‐on molecular orientation of CI‐B3 show its great promise as a HTM candidate for efficient and stable PSCs.

Complex compositional engineering of mixed halides/mixed cations perovskites has recently fostered a rapid progress in perovskite solar cell technology. Here we demonstrate that when 10% of formamidinium (FA+) is simply added into methylammonium lead iodide (MAPbI3) a highly crystalline and compositionally uniform perovskite is formed, self-organizing into a stable “quasi-cubic” phase at room temperature. We reached power conversion efficiency of over 20.2%, the highest value reported to date for FAxMA1−xPbI3 perovskite.

Donor-π-bridge-donor type oligomers (D-π-D) have been studied intensively as active materials for organic optoelectronic devices. In this study, we introduce three new D-π-D type organic semiconductors incorporating thiophene or thienothiophene with two electron-rich TPA units, which can be easily synthesized from commercially available materials. A thorough comparison of their optoelectronic and structural properties was conducted, revealing the strong influence of the extent of longitudinal π-bridge conjugation on both the solid structure of the organic semiconductive materials and their photovoltaic performance when applied as hole transporting materials (HTM) in perovskite solar cells. Single-crystal measurements and time-resolved photoluminescence (TRPL) studies indicate that these coplanar donor-π-donor type HTMs could be promising alternatives to state-of-the-art spiro-OMeTAD, due to the multiple intermolecular short contacts as charge transporting channels and efficient charge extraction properties from the perovskite layer. The optimized devices with <b>PEH-9</b> exhibited an impressive PCE of 16.9% under standard global AM 1.5 illumination with minimized hysteretic behaviour, which is comparable to that of devices using spiro-OMeTAD under similar conditions. Ambient stability after 400 h revealed that 93% of the energy conversion efficiency was retained for <b>PEH-9</b>, indicating that the devices had good long-term stability.