Chemical Design Rules for Non-Fullerene Acceptors in Organic Solar Cells

Efficiencies of organic solar cells have practically doubled since the development of non-fullerene acceptors (NFAs). However, generic chemical design rules for donor-NFA combinations are still needed. Such rules are proposed by analyzing inhomogeneous electrostatic fields at the donor-acceptor interface. It is shown that an acceptor-donor-acceptor molecular architecture, and molecular alignment parallel to the interface, results in energy level bending that destabilizes the charge transfer state, thus promoting its dissociation into free charges. By analyzing a series of PCE10:NFA solar cells, with NFAs including Y6, IEICO, and ITIC, as well as their halogenated derivatives, it is suggested that the molecular quadrupole moment of ca 75 Debye A balances the losses in the open circuit voltage and gains in charge generation efficiency

Mesoscale engineering of photonic glass for tunable luminescence

The control of optical behavior of active materials through manipulation of microstructure has led to the development of high-performance photonic devices with enhanced integration density, improved quantum efficiencies and controllable colour output. However, the achievement of robust light-harvesting materials with tunable, broadband and flatten emission remains a long-standing goal, owing to the limited inhomogeneous broadening in ordinary hosts. Here, we describe an effective strategy for management of photon emission by manipulation of mesoscale heterogeneities in optically active materials. Importantly, this unique approach enables control of dopant-dopant and dopant-host interactions at the extended mesoscale. This allows generating intriguing optical phenomena such as high activation ratio of dopant (close to 100 %), dramatically inhomogeneous broadening (up to 480 nm), notable emission enhancement, and moreover, simultaneously extending emission bandwidth and flattening spectral shape in glass and fiber. Our results highlight that the findings connect the understanding and manipulation at the mesoscale realm to functional behavior at the macroscale, and the approach to managing the dopants based on mesoscale engineering may provide new opportunity for construction of robust fiber light source.National Natural Science Foundation of China (Grant IDs: 11474102, 51202180), the Chinese Program for New Century Excellent Talents in University (Grant ID: NCET-13-0221), Guangdong Natural Science Funds for Distinguished Young Scholar (Grant ID: S2013050014549), Fundamental Research Funds for the Central University, Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, World Premier International Research Center Initiative (WPI), MEXT, JapanThis is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Nature Publishing Group

BenchML: an extensible pipelining framework for benchmarking representations of materials and molecules at scale

Abstract We introduce a machine-learning (ML) framework for high-throughput benchmarking of diverse representations of chemical systems against datasets of materials and molecules. The guiding principle underlying the benchmarking approach is to evaluate raw descriptor performance by limiting model complexity to simple regression schemes while enforcing best ML practices, allowing for unbiased hyperparameter optimization, and assessing learning progress through learning curves along series of synchronized train-test splits. The resulting models are intended as baselines that can inform future method development, in addition to indicating how easily a given dataset can be learnt. Through a comparative analysis of the training outcome across a diverse set of physicochemical, topological and geometric representations, we glean insight into the relative merits of these representations as well as their interrelatedness.</jats:p

Morphology and Charge Transport in P3HT: A Theorist's Perspective

The uses of the Psalms in the Old and New Testaments and a study of Psalm 2.https://scholar.csl.edu/lbipsalmsforstrength/1000/thumbnail.jp