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Quantitative rate determination of elementary reactions is a major task in the study of chemical kinetics. To ensure the fidelity of their determination, progressively tightened constraints need to be placed on their measurement, especially with the development of various notable experimental techniques. However, the evaluation of reaction rates and their uncertainties is frequently conducted with substantial subjectivity due to data source, thermodynamic conditions, sampling range, and sparsity. To reduce the extent of biased rate evaluation, we propose herein an approach of uncertainty-weighted statistical analysis, utilizing weighted average, and weighted least-square regression in statistical inference. Based on the backbone H 2 /O 2 chemistry, rate data for each elementary reaction are collected from the time-history profile in shock tube experiments and high-level theoretical calculations, with their assigned weight inversely depending on uncertainty, which would overall avoid subjective assessments and provide more accurate rate evaluation. Aided by sensitivity analysis, the rates of a few key reactions are further constrained in the less investigated low- to intermediate-temperature conditions using high-fidelity flow reactor data. Good performance of the constructed mechanism is confirmed with validation against the target of the high-fidelity flow reactor data. This study demonstrates a systematic approach for reaction rate evaluation and uncertainty quantification.

We address here the need for a general strategy to control molecular assembly over multiple length scales. Efficient organic photovoltaics require an active layer comprised of a mesoscale interconnected networks of nanoscale aggregates of semiconductors. We demonstrate a method, using principles of molecular self-assembly and geometric packing, for controlled assembly of semiconductors at the nanoscale and mesoscale. Nanoparticles of poly(3-hexylthiophene) (P3HT) or [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were fabricated with targeted sizes. Nanoparticles containing a blend of both P3HT and PCBM were also fabricated. The active layer morphology was tuned by the changing particle composition, particle radii, and the ratios of P3HT:PCBM particles. Photovoltaic devices were fabricated from these aqueous nanoparticle dispersions with comparable device performance to typical bulk-heterojunction devices. Our strategy opens a revolutionary pathway to study and tune the active layer morphology systematically while exercising control of the component assembly at multiple length scales.