• Energy Research

Carbon nanotube-Si and graphene-Si solar cells have attracted much interest recently owing to their potential in simplifying manufacturing process and lowering cost compared to Si cells. Until now, the power conversion efficiency of graphene-Si cells remains under 10% and well below that of the nanotube-Si counterpart. Here, we involved a colloidal antireflection coating onto a monolayer graphene-Si solar cell and enhanced the cell efficiency to 14.5% under standard illumination (air mass 1.5, 100 mW/cm(2)) with a stable antireflection effect over long time. The antireflection treatment was realized by a simple spin-coating process, which significantly increased the short-circuit current density and the incident photon-to-electron conversion efficiency to about 90% across the visible range. Our results demonstrate a great promise in developing high-efficiency graphene-Si solar cells in parallel to the more extensively studied carbon nanotube-Si structures.

The goal of nanotechnology is to build nanodevices that are intelligent, multifunctional, exceptionally small, extremely sensitive and have low power consumption. When the nanodevice is required for applications such as in vivo biomedical sensors, a nanoscale power source is required. Although a battery or energy storage unit is a choice for powering nanodevices, harvesting energy from the environment is an essential solution for building a “self-powered” nanodevice/nanosystem, [ 1 , 2 ] which is an integration of nanodevice(s) and nano-enabled energy scavenging technologies. [ 3 ] Previously, nanogenerators (NGs) have been demonstrated that can convert mechanical energy of low (order of Hz) and high (around 50 kHz) frequencies into electricity by means of piezoelectric zinc oxide nanowires (NWs). [ 4–6 ] A single silicon NW-based heterostructure has been used to fabricate solar cells that are effective for driving an NW-based pH sensor or logic gate. [ 2 ] Still, the most abundant energy available in biosystems is chemical and biochemical energy, such as glucose. In this paper, we report an NW-based biofuel cell (NBFC) based on a single proton conductive polymer NW for converting chemical energy from biofl uids, such as glucose/blood, into electricity, using glucose oxidase (GOx) and laccase as catalyst. The glucose is supplied from the biofl uid and the NW serves as the proton conductor. Although the electrolyte solution is a choice for transferring proton, it is essential to develop a proton conductive NW in some cases, such as the case in Figure S3c (see Section III of the Supporting Information (SI)), in which the anode and cathode solution are separated. A net current is generated

Nanostructures such as carbon nanotubes (CNTs) and semiconducting nanowires are promising candidates for developing next-generation photovoltaics. Here, we report solar cells using individual single-walled or double-walled CNTs and CdSe nanobelts arranged in simple cross-junction configurations. The CNT and CdSe nanobelts form reliable line contacts at their intersections, resulting in efficient heterojunction solar cells with power conversion efficiencies up to 1.87% and stable performance in air over long periods. Both semiconducting and metallic CNTs can form solar cells with CdSe nanobelts, with similar open-circuit voltages but different short-circuit current densities. We can integrate multiple CNTs in parallel with a single nanobelt to construct an array of cross-junction solar cells simultaneously, with scaled current output, indicating the possibility of parallel device connection and large-scale production. Our results show the potential of utilizing one-dimensional nanostructures to design and fabricate high performance photovoltaic devices with well-defined and scalable structures.