Recently, an increasing number of researchers have begun to focus on developing nonfullerene acceptors, so it is very important to synthesize new polymers that are compatible with nonfullerene acceptors. Besides, wide‐ or medium‐bandgap polymer donors could be better to match narrow nonfullerene acceptors. The design of medium‐bandgap (MBG) polymer donors and their application in organic photovoltaics (OPVs) play an important part in the improvement of OPV device performance. This review summarizes the photovoltaic performance of MBG polymers that have been reported during the last decade. Furthermore, their structure–property relationships and device performance are discussed. On the basis of analyzing many polymer structures, guidance toward the design of novel photovoltaic materials might be helpful to understand the basic OPV mechanism and the path towards commercialization.
Many cognitive tasks involve transitions between distinct mental processes, which may range from discrete states to complex strategies. The ability of cortical networks to combine discrete jumps with continuous glides along ever changing trajectories, dubbed latching dynamics, may be essential for the emergence of the unique cognitive capacities of modern humans. Novel trajectories have to be followed in the multidimensional space of cortical activity for novel behaviours to be produced; yet, not everything changes: several lines of evidence point at recurring patterns in the sequence of activation of cortical areas in a variety of behaviours. To extend a mathematical model of latching dynamics beyond the simple unstructured auto-associative Potts network previously analysed, we introduce delayed structured connectivity and hetero-associative connection weights, and we explore their effects on the dynamics. A modular model in the small-world regime is considered, with modules arranged on a ring. The synaptic weights include a standard auto-associative component, stabilizing distinct patterns of activity, and a hetero-associative component, favoring transitions from one pattern, expressed in one module, to the next, in the next module. We then study, through simulations, how structural parameters, like those regulating rewiring probability, noise and feedback connections, determine sequential association dynamics.
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