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Crowdsourced evaluation is a promising method of evaluating engineering design attributes that require human input. The challenge is to correctly estimate scores using a massive and diverse crowd, particularly when only a small subset of evaluators has the expertise to give correct evaluations. Since averaging evaluations across all evaluators will result in an inaccurate crowd evaluation, this paper benchmarks a crowd consensus model that aims to identify experts such that their evaluations may be given more weight. Simulation results indicate this crowd consensus model outperforms averaging when it correctly identifies experts in the crowd, under the assumption that only experts have consistent evaluations. However, empirical results from a real human crowd indicate this assumption may not hold even on a simple engineering design evaluation task, as clusters of consistently wrong evaluators are shown to exist along with the cluster of experts. This suggests that both averaging evaluations and a crowd consensus model that relies only on evaluations may not be adequate for engineering design tasks, accordingly calling for further research into methods of finding experts within the crowd.

A detailed investigation of the functionality of inverted organic photovoltaics (OPVs) using bare Ag contacts as the top electrode is presented. The inverted OPVs without a hole-transporting layer (HTL) exhibit a significant gain in hole-carrier selectivity and power-conversion efficiency (PCE) after exposure in ambient conditions. Inverted OPVs comprised of ITO–ZnO–poly(3-hexylthiophene-2,5-diyl)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM)–Ag demonstrate over 3.5% power conversion efficiency only if the devices are exposed in air for over 4 days. As concluded through a series of measurements, the oxygen presence is essential to obtaining fully operational solar cell devices without HTL. Moreover, accelerated stability tests under damp heat conditions (RH = 85% and T = 65 °C) performed to nonencapsulated OPVs demonstrate that HTL-free inverted OPVs exhibit comparable stability to the reference inverted OPVs. Importantly, it is shown that bare Ag top electrodes can be efficiently used in inverted OPVs using various high-performance polymer–fullerene bulk heterojunction material systems demonstrating 6.5% power-conversion efficiencies.

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