Minghua Tang

Hydrophilic Flower‐Like CuS Superstructures as an Efficient 980 nm Laser‐Driven Photothermal Agent for Ablation of Cancer Cells

Photothermal ablation (PTA) therapy has attracted much interest in recent years as a minimally invasive alternative to conventional approaches, such as surgery and chemotherapy, for therapeutic intervention of specifi c biological targets. [ 1 , 2 ] In particular, near-infrared (NIR, λ = 700–1100 nm) laser-induced PTA, which converts NIR optical energy into thermal energy, has attracted increasing attention, because the NIR laser is absorbed less by biological tissues and the typical penetration depth of the NIR (such as 980 nm) light can be several centimeters in biological tissues. [ 3 , 4 ] A prerequisite for the development of the NIR laser-induced PTA is to gain access to biocompatible and effi cient photothermal coupling agents. As the well-known NIR photothermal conversion agents, gold (Au) nanostructures, including supramolecularly assembled nanoparticles, [ 5–8 ]

Hydrophilic Cu2ZnSnS4 nanocrystals for printing flexible, low-cost and environmentally friendly solar cells

Using Cu2ZnSnS4 (CZTS) nanocrystal-based ink (via a solvothermal route) and roll-to-roll printing, CZTS films are prepared on a Mo-coated Al foil, and then flexible solar cells with a structure of Al foil/Mo/CZTS/ZnS/i-ZnO/ITO/Al–Ni and a power conversion efficiency of 1.94% are constructed, in which all the materials are low-cost and environmentally friendly.

One-pot synthesis of large-scaled Janus Ag–Ag2S nanoparticles and their photocatalytic properties

We report a facile, one-pot route based on thermal decomposition of a single molecular precursor for preparing spherical, eggplant-shaped Janus Ag–Ag2S nanoparticles; these Ag–Ag2S Janus-coupled P25 TiO2 composites show a higher photocatalytic efficiency than those of the Ag2S NPs coupled P25 TiO2 composites and pure P25 TiO2.

In situ preparation of CuInS2 films on a flexible copper foil and their application in thin film solar cells

The in situ preparation of semiconductor films on a flexible metal foil has attracted increasing attention for constructing flexible solar cells. In this work, we have developed an in situgrowth strategy for preparing CuInS2 (CIS) films by solvothermally treating flexible Cu foil in an ethylene glycol solution containing InCl3·4H2O and thioacetamide with a concentration ratio of 1 : 2. The effects of solvothermal temperature, time and concentration on the morphology and phase of the CIS films are investigated. Solvothermal temperature has no obvious effect on the morphology of the final films, but higher temperature is favorable for the growth of CIS films with higher crystallinity. Reactant concentration plays a significant role in controlling the morphology of CIS films; if InCl3·4H2O concentration is relatively low (≤0.042 M), single-layered CIS films can be produced, which are composed of high ordered potato chips shaped nanosheets, otherwise, it prefers to form a double-layered film, for which the lower layer is similar CIS ordered nanosheets while the upper layer is composed of flower shaped superstructures. A possible mechanism of the CIS films is also investigated. UV-vis measurements show that all these CIS films possess a direct bandgap energy of 1.48 eV, appropriate for the absorption of the solar spectrum. Finally, single-layered CIS films on Cu foil were employed for fabricating flexible solar cells with a structure of Cu foil/CuInS2/CdS/i–ZnO/ITO/Ni–Al, and the resulting cells yield a power conversion efficiency of 0.75%. Further improvement of the efficiencies of the solar cells can be expected by optimizing the morphology, structure and composition of the CIS films, as well as the fabrication technique.

In situ growth of CuInS2 nanocrystals on nanoporous TiO2 film for constructing inorganic/organic heterojunction solar cells

Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2( CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as ‘petals’ with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure.

The Application of Inorganic Nanomaterials in Dye-Sensitized Solar Cells

Energy crisis and environment pollution cause a great quest and need for environmentally sustainable energy technologies. Among all the renewable energy technologies, photovoltaic technology utilizing solar cell has been considered as the most promising one (Chen et al., 2007a; Gratzel, 2001). As early as in 1954, researchers demonstrated the first practical conversion from solar radiation to electricity by a p-n junction type solar cell with 6% efficiency (Chapin et al., 1954). Up to now, the common solar power conversion efficiencies of this type solar cell are beyond 15% (Tributsch, 2004). Unfortunately, the relatively high cost of manufacturing and the use of toxic chemicals have prevented their widespread use, which prompts the search for high efficient, low cost and environmentally friendly solar cells. Semiconductor with a very large bandgap, such as TiO2, ZnO and SnO2, can be employed to construct solar cells. But these materials can only be excited by ultraviolet or near-ultraviolet radiation that occupies only about 4% of the solar light. Dye molecules as light absorbers for energy conversion have shaped evolution via the process of photosynthesis and photosensoric mechanisms (Tributsch, 2004). Dye sensitization of semiconductor with a wide band-gap has provided a successful solution to extending the absorption range of the cells to long wavelength region. This approach also presents advantages over the direct band-toband excitation in conventional solar cells, since attached dyes, rather than the semiconductor itself, are the absorbing species (Garcia et al., 2000). Importantly, light absorption and charge carrier transport are separated, and the charge separation takes place at the interface between semiconductor and sensitizer, preventing electron–hole recombination. Since the discovery of the photocurrents resulting from dye sensitization of semiconductor electrodes in 1968, dyes have been widely used in electrochemical energy converting cells (Tributsch, 1972). During the first years of the sensitized solar cell research, most studies were made with single crystal oxide samples, because by eliminating grain boundaries and high concentrations of surface states the interpretation of the results became more transparent (Tributsch, 2004). However, at that time, the power conversion efficiencies were very low (< 1%). Tsubomura et al. reported a breakthrough in the conversion efficiency in 1976 (Tsubomura et al., 1976). They used the powdered high porosity multi-crystalline ZnO instead of single crystal semiconductor, resulting in a significant increase of the surface area of the electrode. When the dye (Rose Bengal) was used as the sensitizer, an energy efficiency of 1.5% was obtained for light incident within the absorption spectrum of the sensitizer.