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In recent years, microfluidic bioreactors have become important in chemical production; however, the production cost is high, and it becomes difficult to balance scale, efficiency, and cost. Therefore, a low-cost, efficient, high-delivery-capacity, green-fluid reactor is urgently required. Herein, a cellulose bioreactor with dual-scale directional channels and a porous inner wall is reported for the continuous catalytic conversion of polydatin into resveratrol. The dual-scale directional channel structure endows the reactor with high mass transfer speed and large transport capacity, resulting in fast fluid diffusion rate and more severe "disturbance" inside the reactor. It accelerates the mass transfer state of the whole reaction and further improves the catalytic performance compared to the uniform channel reactor. The reactor can achieve a high conversion rate of 98.58% of resveratrol within 2 h and exhibits excellent stability, owing to which it has broad application prospects in catalytic reactions, and helps derive a new approach for constructing fluid catalysis bioreactors. [ABSTRACT FROM AUTHOR]

Microfluidic biocatalytic reactors have attracted widespread attention in recent years, but the production cost is generally high, which makes it difficult to meet the needs of large-scale industrial production. Developing a low-cost, green fluid reactor has become an urgent requirement. Here, inspired by the three-dimensional hierarchical structure of natural wood, a cellulose-based bionic microfluidic biocatalytic reactor with vertically aligned channels and a porous inner wall is reported for the continuous fluid catalytic conversion of polydatin to resveratrol. NiO nanoparticles were immobilized on cellulose-based bionic materials as metal arms to adsorb poly-histidine-tagged enzymes to form a stable and efficient biocatalytic reactor. Due to the unidirectionally aligned channels and porous inner wall, the fluid in different channels of the bionic xylem reactor is disturbed through the porous inner wall, which greatly prolongs the residence time for the fluid inside the reactor and increases the probability for contact with the enzyme, improving the internal mass and heat transfer efficiency to achieve high catalytic activity (98.69% treatment efficiency) and excellent stability (maintain a conversion rate of more than 90% within 15 days). Because of the good and stable enzyme immobilization and high catalytic activity of the reactor, it can greatly simplify industrial upstream and downstream production and has broad application prospects for catalytic reactions. [ABSTRACT FROM AUTHOR]

Although the power conversion efficiency (PCE) of organometal halide perovskite solar cells (PSCs) has reached 25.2%, control of the crystallization process and its impact on film quality is still one of the main challenges. Here, a new perovskite growth method using formamidinium chloride (FACl) as an additive is introduced to enlarge the crystal grain size and improve the quality of the perovskite film. Strikingly, the champion power conversion efficiency of FA0.85MA0.15PbIxBr3−x-based and Cs0.05FA0.85MA0.10Pb(I0.97Br0.03)3-based PSC devices reaches 21.02% and 22.56%, respectively. The hysteresis index is found to decrease from 0.101 to 0.005, which is attributed to suppressed ion migration and surface charge trapping. Besides, the better film quality with FACl significantly increases the environmental stability of the perovskite films, yielding devices that maintain 90% of their initial efficiency after 1200 h under ambient air conditions, whereas the pristine devices without FACl only maintain 50% of their initial efficiency. Our solar cells processed with additives also achieve retardation of degradation of the PCE with a considerably enhanced environmental stability. This work offers a promising route through crystallization management to achieve high performance and stable PSCs. [ABSTRACT FROM AUTHOR]

Obtaining control over the crystallographic growth kinetics in polycrystalline perovskites has become a central topic toward achieving high efficiency and stable perovskite solar cells. Inspired by the chemistry of halogen bonding, we introduce an effective processing strategy using diiodoperfluoroalkyl and diiodoalkyl additives to modulate the crystallization, traps and resultant photophysical processes in methylammonium halide (CH3NH3PbI3) perovskite solar cells that can reach a power conversion efficiency (PCE) exceeding 20% associated with a negligible hysteresis with a compact TiO2 based planar structure. Aided by combinatorial analyses with X-ray photoelectron spectroscopy, dynamic light scattering and density functional theory calculation, we ascribe the achieved modulation of the crystallization in CH3NH3PbI3 to the formation of halogen bonding between the iodine in the additives and halide anions in perovskite precursor solutions. Benefitting from the modification with additives, the resultant solar cells exhibit a decrease in Shockley–Read–Hall recombination due to the suppressed charge trapping which explains the improvement of PCE. Our solar cells processed with additives also show retardation of degradation with a considerably enhanced environmental stability. This work offers a promising route through additive management to achieve high performance and stable perovskite solar cells. [ABSTRACT FROM AUTHOR]

Here we investigate temperature-dependent charge transport in solution-processed methylammonium lead triiodide (MAPbI3) perovskite thin films with steady-state mobility measurements. Based on control of the thickness (L) of the MAPbI3 films, one attains tunability in the carrier mobility, trap density and recombination that lead to alterations in the device characteristics. We find that the increased hole mobility in MAPbI3 with incremental variations in L is associated with reduction in the trap concentration and Shockley–Read–Hall (SRH) recombination. By interrogating the ideality factor, we identify that the SRH charge recombination is present in the optimal solar cell. Of interest, the impact of traps on recombination becomes weakened and eventually is overwhelmed by bimolecular recombination with increasing L. Photoluminescence decay kinetics reveal that the PL related to surface and bulk recombination is longer-lived at larger L, in line with the results based on electrical analysis. The meliorated transport properties with reduced charge trapping in MAPbI3 films can correlate to the slightly enhanced crystallinity and homogeneity in the grain size distribution in thicker films. The combinatorial study shows that the transport properties alongside traps in MAPbI3 films are tunable simply by the physical parameter of L. Meanwhile, our work points to the necessity to further reduce the trap density so as to boost the photovoltaic performance using perovskite thin films. [ABSTRACT FROM AUTHOR]