Onion-like carbon (OLC) was synthesised by annealing detonation nanodiamond for 1.5 h at temperatures from 500 to 1400°C and at a vacuum of 1 Pa. The results showed that the nanodiamond was transformed into the amorphous carbon (a-C) at first and then the a-C was transformed into the OLC gradually with the increase in annealing temperature. Moreover, at the annealing temperature of 600°C, the nanodiamond started transforming into a-C from the edge of the nanodiamond particle (1 1 1) crystal plane. At the annealing temperature of 750°C, the nanodiamond was transformed into the a-C completely. At the annealing temperature of 850°C, the a-C began transforming into the OLC at the edge area. At the annealing temperature of 1000°C, the OLC particle with a size smaller than 5 nm was synthesised. However, in the centre of the OLC particle, untransformed a-C coexisted. At the annealing temperature of 1100°C, the microstructure of the OLC particle with a size smaller than 5 nm became optimised. At the annealing temperature of 1200°C, the OLC particle with a size larger than 5 nm was fabricated. There was also untransformed a-C coexisting in the centre of the OLC particle. At the annealing temperature of 1350°C, all the a-C was transformed into the OLC. The average size of the OLC was approximately 5 nm, which was the same as that of the nanodiamond. The layers of the OLC were varied from several to 12.

Aqueous CdTe quantum dots solar cells have been successfully fabricated by the blade coating method on the magnesium zinc oxide (Zn_1−xMg_xO or ZMO) window layer. Compared with the ZMO mono-window layer, the ZMO/CdS bi-window layer can decrease the interface recombination effectively due to the lower lattice mismatch and fast interdiffusion between CdS and CdTe. Moreover, the high temperature annealing of the CdTe quantum dots absorbed layer passivates the grain boundary of the CdTe crystalline via the replacement reaction of tellurium with sulfur. Finally, the conversion efficiency of our aqueous CdTe quantum dots solar device is improved from 3.21% to 8.06% with the introduction of the CdS interlayer and high temperature CdCl₂ annealing. Our aqueous CdTe quantum dots solar devices show a large open circuit voltage and fill factor which are comparable with the conventional devices that are fabricated with organic CdTe quantum dots. We believe that it is the spike-like conduction band alignment between the ZMO and CdTe absorbed layer that reduces the majority carrier concentration, leading to the decrease in interface recombination probability.

By adding hydrogen peroxide (H ₂ O ₂ ) to the solution, a more compact cadmium sulfide (CdS) film with larger optical band gap is fabricated by chemical bath deposition method. The oxidation of CdS is confirmed by the formation of cadmium sulfate (CdSO ₄ ) in the CdS window layer via x-ray photoelectron spectroscopy investigation. The analysis of quantum efficiency considering the alloy CdS _1−y Te _y shows that the oxygenated CdS suppress the S-Te interdiffusion, which promotes the spectral response in short-wave range. Moreover, this oxygenated CdS layer promoted the conversion efficiency of the cadmium telluride (CdTe) based solar cell from11.2% to 14.0% due to the improvement of open-circuit voltage and the fill factor. The transport mechanisms of saturation current are evaluated by temperature dependent current–voltage curves. Results show that the oxygenated window layer reduces both the interfacial and bulk recombination, thus improves the ideality factor. The decrease of bulk recombination in depletion region is attributed to the fewer trap level induced from S-Te interdiffusion. The decrease of interfacial recombination is attributed to the larger optical band gap of oxygenated CdS, which results in a spike-like conduction band alignment at CdS/CdTe heterojunction.

Cu_0.7Mn_0.3O films were deposited by Plasma Enhanced Chemical Vapor Deposition and annealed in different atmospheres. The XRD diffraction results indicate that samples annealed in air and N₂ both show pure CuO phases, while the film annealed in O₂ has a secondary phase CuMn₂O₄. The content of Mn was confirmed by Energy dispersive X-ray spectroscopy. The M-T and M-H curves show that the average magnetic moment of the films prepared in O₂ is larger than those prepared in air and in N₂ atmosphere. Ferromagnetic segments Mn-O-Cu-O-Mn can be used to understand the ferromagnetism of CuO under heavily Mn-doping. And the magnetic moment per Mn ions calculated on the base of this chain model is consistent with the experimental result.