A rapid classification method of aluminum alloy based on laser-induced breakdown spectroscopy and random forest algorithm

As an important non-ferrous metal structural material most used in industry and production,aluminum(Al) alloy shows its great value in the national economy and industrial manufacturing.How to classify Al alloy rapidly and accurately is a significant, popular and meaningful task.Classification methods based on laser-induced breakdown spectroscopy(LIBS) have been reported in recent years. Although LIBS is an advanced detection technology, it is necessary to combine it with some algorithm to reach the goal of rapid and accurate classification. As an important machine learning method, the random forest(RF) algorithm plays a great role in pattern recognition and material classification. This paper introduces a rapid classification method of Al alloy based on LIBS and the RF algorithm. The results show that the best accuracy that can be reached using this method to classify Al alloy samples is 98.59%, the average of which is 98.45%. It also reveals through the relationship laws that the accuracy varies with the number of trees in the RF and the size of the training sample set in the RF. According to the laws, researchers can find out the optimized parameters in the RF algorithm in order to achieve,as expected, a good result. These results prove that LIBS with the RF algorithm can exactly classify Al alloy effectively, precisely and rapidly with high accuracy, which obviously has significant practical value.

Thick Active-Layer Organic Solar Cells

Organic solar cells(OSCs)present a promising renewable energy technology due to their cost-effectiveness,adaptability,and lightweight nature.The advent of non-fullerene acceptors has further boosted their significance,allowing for power conversion efficiencies surpassing 19%even with an active layer thickness of about 100 nm.However,in order to achieve large scale production,it is necessary to fabricate OSCs with thicker active layers exceeding 300 nm that are compatible with large-area printing techniques.Nevertheless,OSCs with thick active layers have inferior performance compared to those with thin active layers.To expedite the transition of OSCs from laboratory to industrial high-throughput manufacturing,considerable efforts have been made to comprehend the performance limitations of thick active-layer OSCs,develop novel photoactive materials that are high-performance and tolerant towards the thickness of the active layer,and optimize the morphology of the photoactive layer and device structure.This review aims to provide a comprehensive summary of the mechanisms that lead to efficiency loss in thick active-layer OSCs,the representative works on molecular design,and the optimization strategies for high-performance thick active-layer OSCs,and the remaining challenges that must be addressed.

Enhancing Photovoltaic Performance of Asymmetric Fused-Ring Electron Acceptor by Expanding Pyrrole to Pyrrolo[3,2-b]pyrrole

We propose a strategy to improve performance of unidirectionally extended fused-ring electron acceptors by using pyrrolo[3,2-b]pyrrole to replace pyrrole ring, and design two asymmetric nonfullerene acceptors 1PIC and 2PIC. Replacing pyrrole in 1PIC with pyrrolo[3,2-b]pyrrole remarkably red-shifts absorption peak by 109 nm, elevates the HOMO and LUMO energy levels, and improves electron mobility. The photovoltaic devices based on blend of PM6 donor and 2PIC acceptor exhibit power conversion efficiency as high as 12.6%, which is much higher than that of PM6:1PIC (3.53%), due to more efficient exciton generation and dissociation, faster and more balanced carrier transport and less charge recombination.

Revealing the Unusual Efficiency Enhancement of Organic Solar Cells with Polymer-Donor-Treated Cathode Contacts

The metal oxides with low trap density of states as the electron transport layer are crucial for the high performance of the organic solar cells(OSCs).It is universally acknowledged that modifying n-type metal oxide contacts with polymer donors will harm the carrier extraction on account of the mismatched energy level.However,we find that modifying interlayer consisting of the alcohol amines with some polymer donor additive can unusually enhance the performance of the OSCs.Compared with triethanolamine(TEA)passivated ZnO,TEA:polymer donor treated ZnO shows lower trap density and enhances electron mobility resulting in higher current density in OSC devices.Here,we reveal that the enhanced oxygen-defect passivation ability of TEA with polymer additive is attributed to the enhanced negative electrostatic potential of TEA owing to the hydrogen bond formation between the polymer and the hydroxyl group in TEA.This strategy that enhancing the negative electrostatic potential of the passivators for improving oxygen defect passivation can be extended to other types of organic electronic devices.