Hydrogenated amorphous Si （a-Si：H） is a promising material for photovoltaic applications due to its low cost, high abundance, long lifetime, and non-toxicity. We demonstrate a device designed to investigate the eff...Hydrogenated amorphous Si （a-Si：H） is a promising material for photovoltaic applications due to its low cost, high abundance, long lifetime, and non-toxicity. We demonstrate a device designed to investigate the effect of nanostructured back reflectors on quantum efficiency in photovoltaic devices. We adopt a superstrate configuration so that we may use conventional industrial light trapping strategies for thin film solar cells as a reference for comparison. We controlled the nanostructure parameters via a wafer-scale self-assembly technique and systematically studied the relation between nanostructure size and photocurrent generation. The gain/loss transition at short wavelengths showed red-shifts with decreasing nanostructure scale. In the infrared region the nanostructured back reflector shows large photocurrent enhancement with a modified feature scale. This device geometry is a useful archetype for investigating absorption enhancement by nanostructures.展开更多
We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion ba...We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon （a-Si） works as the active material to store electrical energy, and the pre-coated carbon nanofibers （CNFs） serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of 〉2000 mA.h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of 〉98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.展开更多
文摘Hydrogenated amorphous Si （a-Si：H） is a promising material for photovoltaic applications due to its low cost, high abundance, long lifetime, and non-toxicity. We demonstrate a device designed to investigate the effect of nanostructured back reflectors on quantum efficiency in photovoltaic devices. We adopt a superstrate configuration so that we may use conventional industrial light trapping strategies for thin film solar cells as a reference for comparison. We controlled the nanostructure parameters via a wafer-scale self-assembly technique and systematically studied the relation between nanostructure size and photocurrent generation. The gain/loss transition at short wavelengths showed red-shifts with decreasing nanostructure scale. In the infrared region the nanostructured back reflector shows large photocurrent enhancement with a modified feature scale. This device geometry is a useful archetype for investigating absorption enhancement by nanostructures.
基金We acknowledge financial support from the National Science Foundation （CCF 0726815 and CCF 0702204）.
文摘We have successfully fabricated a hybrid silicon-carbon nanostructured composite with large area （about 25.5 in^2） in a simple fashion using a conventional sputtering system. When used as the anode in lithium ion batteries, the uniformly deposited amorphous silicon （a-Si） works as the active material to store electrical energy, and the pre-coated carbon nanofibers （CNFs） serve as both the electron conducting pathway and a strain/stress relaxation layer for the sputtered a-Si layers during the intercalation process of lithium ions. As a result, the as-fabricated lithium ion batteries, with deposited a-Si thicknesses of 200 nm or 300 nm, not only exhibit a high specific capacity of 〉2000 mA.h/g, but also show a good capacity retention of over 80% and Coulombic efficiency of 〉98% after a large number of charge/discharge experiments. Our approach offers an efficient and scalable method to obtain silicon-carbon nanostructured composites for application in lithium ion batteries.
