J.S. Lian

Structural, optical and electrical characterization of gadolinium and indium doped cadmium oxide/p-silicon heterojunctions for solar cell applications

Gadolinium and indium co-doped CdO thin films were prepared by a pulsed laser deposition method. The XRD and XPS results indicated that Gd3+ and In3+ ions occupied locations in the interstitial positions and/or Cd2+-ion vacancies in the CdO lattice. The FESEM images showed that the films were homogeneous and consisted of nanograins with a size range of 23–40 nm. The optical band gap of the CdO thin films can be engineered over a wide range of 2.72–3.56 eV by introducing Gd and In dopants. Such transparent semiconducting Gd and In co-doped CdO films were then grown on p-type Si substrates to fabricate n-CdO/p-Si heterojunction devices. The important junction parameters such as the series resistance (Rs), ideality factor (n) and Schottky barrier height (Φb) were determined by analysing different plots from the current density–voltage (J–V) characteristics. The obtained results indicated that the electrical properties of the heterojunction diodes were controlled by the dopant concentration. The p-Si/n-Cd1−x−yGdxInyO heterojunction diode showed the best values of open circuit voltage, Voc = 1.04 V and short circuit current density, Jsc = 11.4 mA cm−2 under an illumination intensity of 100 mW cm−2, which was suitable for solar cell applications.

Optical properties of Cu-doped ZnO nanoparticles experimental and first-principles theory research

Zn1−xCuxO nanoparticles were synthesized by using sol–gel method. Structure and optical properties of Zn1−xCuxO nanoparticles were studied experimentally and theoretically. The simulations are based upon the Perdew-Burke-Ernzerhof form of generalized gradient approximation within the density functional theory. The results showed that the UV emission is effectively quenched and the emission in visible-light region is enhanced by Cu-doping, which are theoretically explained to be attributed to the electronic intra-band transition from the occupied bands to the unoccupied ones under irradiation. Therefore, Zn1−xCuxO system may be a potential candidate for photocatalytic in visible light range.

Solvothermal synthesis of nanocrystalline ZnO with excellent photocatalytic performance

Abstract We reported a facile way to synthesize nanocrystalline ZnO particles with excellent photocatalytic performance. Their microstructures and optical properties were characterized by X-ray diffraction, field emission scanning electron, transmission electron microscopy, photoluminescence spectra and ultraviolet–visible (UV–Vis) spectra. Photocatalytic tests showed the as-prepared ZnO particles had a good activity for photodegradation of organic dyes under UV–Vis light irradiation, which was comparable with that of P25 TiO2, a commercial standard photocatalyst. Furthermore, the sample could be easily sedimentary from the reaction system, which was favorable for the separation and reuse. Meanwhile, the photocatalytic performance of the samples exhibited no obvious reduction in the activity after five recycles of photodegradation, demonstrating its superior reusability. We attributed the superior performance to the efficient synergistic effect resulted from the small nano size, as well as the appropriate oxygen vacancies in the ZnO lattice. Our work might be promising for the application of ZnO-based photocatalysts due to its low cost, easy process, and good performance.