There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.

Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

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Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

/pdf/visible-light-photocatalysis-in-nitrogen-doped-titanium-np6nklr9gh.pdf

Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Photoelectrochemical properties of supramolecular composite of fullerene nanoclusters and 9-mesityl-10-carboxymethylacridinium ion on SnO2.

Shape- and functionality-controlled organization of porphyrin derivatives-C60 supramolecular assemblies using TiO2 nanotubes and nanoparticles has been achieved for the development of photochemical solar cells. The differences in the efficiency of light-energy conversion of these solar cells are explained on the basis of the geometrical orientation of the porphyrins with respect to the TiO2 surface and the supramolecular complex formed with C60. The maximum photon-conversion efficiency (IPCE) of 60% obtained with TiO2 nanotube architecture is higher than the value obtained with nanoparticle architecture. The results presented in this study show the importance of substrate morphology in promoting electron transport within the mesoscopic semiconductor film.

Shape- and functionality-controlled organization of TiO2-porphyrin-C60 assemblies for improved performance of photochemical solar cells.

The efficiency of photovoltaic materials is compromised by their inability to capture all the energy absorbed when excited by high-energy photons. Such absorption creates 'hot' electrons, and now their transfer from excited lead selenide nanocrystals to an electron acceptor provides a necessary initial step towards tapping their 'lost' energy.

Photovoltaics: capturing hot electrons.

http://pubs.acs.org/doi/pdf/10.1021/acsenergylett.7b00361

Redox Flow Batteries

Thiocyanate ion treatment, usually either LiSCN or KSCN, of the absorbing semiconductor before deposition of a CuSCN hole conducting layer is known to improve the performance of extremely thin absorber (ETA) solar cells by reducing the cell resistivity. However, in spite of several hypotheses, the mechanism behind this treatment outcome remains elusive. In this study, the interface between Sb2S3 and CuSCN in an ETA cell is investigated with surface spectroscopy and transient absorption spectroscopy to establish the mechanistic aspects of the KSCN treatment and the role it plays in improving the photovoltaic performance. The prominent factors that dictate the cell performance are (a) doping the interfacial CuSCN and thus preventing the formation of a sub-μm depleted layer and (b) passivating charge traps at the Sb2S(O)3 surface, which increases the rate of hole transfer from the absorber to the hole conductor. We further show that the treatment works just as well in improving photovoltaic performance when ...

Prashant V. Kamat

Papers

Photoelectrochemical properties of supramolecular composite of fullerene nanoclusters and 9-mesityl-10-carboxymethylacridinium ion on SnO2.

Shape- and functionality-controlled organization of TiO2-porphyrin-C60 assemblies for improved performance of photochemical solar cells.

Photovoltaics: capturing hot electrons.

Redox Flow Batteries

Band Diagram and Effects of the KSCN Treatment in TiO2/Sb2S3/CuSCN ETA Cells