•We fabricated organic/inorganic nanocomposites P3HT@TiO2 NRs and P3HT@ZnO/TiO2 NRs.•The optical properties of P3HT are strongly influenced by inorganic nanostructures.•The nanocomposites show strong light absorption and evident PL quenching.•The organic/inorganic nanocomposite exhibit high photoactivity.•ZnO/TiO2 NTs are superior to TiO2 NTs in composing nanocomposites with P3HT.Organic/inorganic nanocomposites composed of a ploy(3-hexylthiophene) (P3HT) film and TiO2 nanotubes or ZnO-coated TiO2 (ZnO/TiO2) nanotubes were fabricated and the influence of the inorganic nanostructures on the optical properties correlated with their photoactivity was studied. The structures of the organic/inorganic nanocomposites were characterized by X-ray diffraction and Raman backscattering spectroscopy. The optical properties were evaluated by measuring the optical absorption and photoluminescence. The TiO2 nanotubes exhibit anatase structure and the ZnO coating is structured with hexagonal wurtzite. The inorganic nanostructures are fully covered by the P3HT films with some P3HT infiltrating into the lacunas of the one-dimensional nanostructures. The P3HT-covered TiO2 NTs show strong optical absorption and present evident photoluminescence quenching. Nano-heterostructured ZnO/TiO2 NTs are superior to nanostructured TiO2 NTs in composing organic/inorganic nanocomposites with P3HT. The presence of a thin ZnO coating between the P3HT film and the TiO2 nanotubes further increases light absorption and quenches photoluminescence, revealing efficient generation of excitons by optical excitation and suppression of radiative recombination of photo-generated excitons, and suggesting that the organic/inorganic nanocomposite P3HT-covered ZnO/TiO2 nanotubes exhibits high photoactivity and an enhanced light harvesting efficiency can be anticipated. The temperature-dependent photoluminescence was also measured for an examination of π-stacking aggregation and a discussion of exciton coupling in P3HT at different temperatures.

•Laser ablation of a Zn target and an Al target induces a Zn plume and an Al plume.•ECR discharge of O2/N2 mixed gas generates an O-N plasma.•The expansion of the Zn and Al plumes in the O-N plasma forms an O-N-Zn-Al plasma.•The formed O-N-Zn-Al plasma is very reactive and contains numerous active species.•The O-N-Zn-Al plasma can be used for the deposition of Al-N co-doped ZnO films.Using optical emission spectroscopy measurements, the plasma formed for the preparation of zinc and aluminum co-doped ZnO films is studied. The O2/N2 mixed gas is excited by electron cyclotron resonance microwave discharge, generating an oxygen-nitrogen plasma. A zinc plume and an aluminum plume are induced by pulsed laser ablation of a zinc target and an aluminum target. The expansion of the plumes in the oxygen-nitrogen plasma enhances the excitation of the species of the oxygen-nitrogen plasma, while the ablated zinc and aluminum species are frequently excited at the same time, forming a highly reactive oxygen-nitrogen-zinc-aluminum plasma containing active oxygen- and nitrogen-related species excited from the O2/N2 gas and zinc and aluminum species ablated from the zinc and aluminum targets, as well as nitric oxide molecules produced in the plasma. The active oxygen species compose a reactive oxygen-containing gaseous environment for oxide formation, and the active zinc species react with the active oxygen species for ZnO film deposition, while the active nitrogen and aluminum species are in situ co-doped in the growing ZnO film. The optical properties of ZnO films are improved by zinc and aluminum co-doping including blue shifting of absorption edge, widening of band gap and preserving of high transparency.Download high-res image (77KB)Download full-size image

We report on the sensitizing of CdS-coated ZnO (CdS/ZnO) nanorods (NRs) by Ag nanoparticles (NPs) embedded between the CdS coating and the ZnO nanorod and the improved optical and photoelectrochemical properties of the Ag NP-sandwiched nanostructure CdS/Ag/ZnO NRs. The CdS/Ag/ZnO NRs were fabricated by growing Ag NPs on hydrothermally grown ZnO NRs and subsequently depositing CdS coatings followed by subsequent N2 annealing. The structure of the fabricated CdS/Ag/ZnO NRs was characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman backscattering, revealing that the ZnO NRs and the CdS coatings are both structured with hexagonal wurtzite and the Ag NPs contact well with ZnO and CdS. Optical properties were evaluated by measuring optical absorption and photoluminescence, showing that the Ag NPs behave well as sensitizers for optical property improvement and the CdS/Ag/ZnO NRs exhibit better photoresponse in a wide spectral region than CdS/ZnO because of plasmon-enhanced absorption due to the embedment of Ag NPs. The Ag NPs also serve as electron relays from CdS to ZnO, facilitating electron transfer from the CdS coatings to the ZnO NRs. The excellent photoresponse and efficient electron transfer make the CdS/Ag/ZnO NRs highly photoelectrochemically active. The CdS/Ag/ZnO NRs fabricated on indium–tin oxide present much better photoelectrochemical performance as photoanodes working in the visible region than CdS/ZnO NRs without Ag NPs. Under visible illumination, a maximum optical-to-chemical conversion efficiency of 3.13% is obtained for CdS/Ag/ZnO NR photoanodes against 1.35% for CdS/ZnO NR photoanodes.Keywords: Ag nanoparticle; CdS-coated ZnO nanorod; localized surface plasmon resonance; photoelectrochemical property; photoresponse; sandwiched nanostructure;

•ZnO and Al-doped ZnO films are deposited by plasma-assisted pulsed laser deposition.•The plasmas formed during film deposition are studied by optical emission spectroscopy.•The formed plasmas are very reactive.•The plasmas contain a variety of excited and energetic atomic and molecular species.•The reactive plasmas are responsible for efficient ZnO film deposition and Al doping.An oxygen-zinc plasma and an oxygen-zinc-aluminum plasma are formed by pulsed laser ablation of a Zn target or pulsed laser co-ablation of a Zn target and an Al target in an electron cyclotron resonance (ECR) discharge-generated oxygen plasma for the deposition of ZnO and Al-doped ZnO (AZO) films. The plasmas are characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy. Both the oxygen-zinc plasma and the oxygen-zinc-aluminum plasma contain excited species originally present in the working O2 gas and energetic species ablated from the targets. The optical emission of the oxygen-zinc-aluminum plasma is abundant in the emission bands of oxygen molecular ions and the emission lines of mono-atomic oxygen, zinc and aluminum atoms and atomic ions. The time-integrated spectra as well as the time-resolved spectra of the plasma emission indicate that the oxygen species in the ECR oxygen plasma experience additional excitation by the expanding ablation plumes, and the ablated species are excited frequently when traveling accompanying the plume expansion in the oxygen plasma, making the formed plasma highly excited and very reactive, which plays an important role in the reactive growth of ZnO matrix and the in-situ doping of Al into the growing ZnO matrix. The deposited ZnO and AZO films were evaluated for composition analysis by energy dispersive X-ray spectroscopy, structure characterization by X-ray diffraction and optical transmission measurement. The deposited ZnO is slightly rich in O. The Al concentration of the AZO films can be controlled and varied simply by changing the repetition rate of the laser used for Al target ablation. Both the ZnO and the AZO films are featured with hexagonal wurtzite crystal structure and exhibit high optical transparency in a wide spectral region. Al doping results in an improvement in the ultraviolet transparency, a blue shift in the absorption edge and a widening of the band gap.

Nearly oriented ZnO nanorods with a mean diameter of ∼200 nm and length of 0.8 to 1.7 μm were prepared directly on lattice-mismatched Si (100) substrate by pulsed laser deposition without catalysts. In correlation with the detailed characterization of the morphology, crystalline structure, and oxide phases of the prepared ZnO nanorod arrays, the photoluminescence and lasing properties were studied. At room temperature, the ZnO nanorods emit strong near band edge emission resulting from radiative recombination of free excitons generated by ultraviolet light excitation. The random-lasing-like stimulated emission is observed at high optical pumping at room temperature, which centers around 382.8 nm and results from the superposition of guided lasing modes in different nanorods. The individual peaks as well as the stimulated emission as a whole show red shifts as the pumping intensity increases.