Concrete embedded dye-synthesized photovoltaic solar cell.

This work presents the concept of a monolithic concrete-integrated dye-synthesized photovoltaic solar cell for optical-to-electrical energy conversion and on-site power generation. The transport measurements carried out in the dark revealed the presence of VOC of ~190 mV and ISC of ~9 µA, induced by the electrochemical conversion of concrete-supplied ionic impurities at the electrodes. The current-voltage measurements performed under illumination at incident optical powers of ~46 mW confirmed the generation of electrical power of ~0.64 µW with almost half generated via battery effect. This work presents a first step towards realizing the additional pathways to low-cost electrical power production in urban environments based on a combined use of organic dyes, nanotitania and concrete technology.

Comment on: "Photocurrent amplification at carbon nanotube-metal contacts".

Lien et al. (Adv. Mater. 2006, vol. 18, p. 98) reported on photocurrent generation in SWNT thin films suspended across metal electrodes at zero bias and the effect was attributed to the Schottky contacts formed at the nanotube-metal interfaces. By performing a set of independent experiments and tests on similarly engineered two-terminal devices and analyzing the results reported in said paper we show that the response is not associated with the contacts or temperature-induced conductance change (bolometric effect), but is instead caused by an optically induced thermovoltaic effect.

Fabrication of Cd(3)As(2) nanowires by direct vapor-solid growth, and their infrared absorption properties.

In this work the authors introduce and provide details of the synthesis and spectral characterization of single-crystal nanowires in less common, high performance, group II-V semiconductors such as Cd(3)As(2). The growth mechanism critically deviates from a known vapor-liquid-solid one by being completely non-catalytic and involving only two states: vapor and solid. The resultant nanowires range from ∼50 to 200 nm in diameter and reach lengths up to tens of micrometers, with their fast growth direction being normal to the (112) crystal planes. According to infrared (IR) optical absorption measurements, the nanowires have several IR active direct type light absorption transitions at 0.11, 0.28 and 0.54 eV, suggestive of their possible utility in low cost optoelectronic devices and photodetectors operating in the long wavelength range of the electromagnetic spectrum.