First-principles study of structure, electrical and optical properties of Al and Mo co-doped ZnO

AZO, MZO and MAZO, the new photosensitive materials prepared by aluminum or molybdenum doping zinc oxide, has received attention due to its potential as a transparent conductive layer for thin film solar cells. In this present, the effects of Al and Mo doping on the structure, electronic and photoelectric properties of ZnO were studied by means of the first-principles method based on density functional theory (DFT). The results indicated that the doping systems were n-type semiconductor, and the carrier concentration and conductivity of AZO, MZO and MAZO were remarkably improved. More interestingly, compared with Al doping, only small amount of Mo doping concentration could make MZO and MAZO possess higher carrier concentration and conductivity. Furthermore, the investigation results of the optical properties showed that Mo doping deteriorated the optical properties of the transparent conductive films in the visible spectrum. Whilst, the transmittance of AZO deteriorated in the long-wavelength (LW) region of visible spectrum, and ameliorated in the short-wavelength (SW) region. Significantly, MAZO had high transmittance in the whole visible range after Al and Mo co-doping, which means MAZO thin films possessed excellent transparency as well as high conductivity. Investigation results contribute theoretically to the preparation of MAZO transparent conductive films.

Automated summary

This study investigated the effects of Al and Mo doping on ZnO transparent conductive films, revealing that Mo doping can improve carrier concentration and conductivity but deteriorate optical properties. Co-doping with Al and Mo can result in MAZO thin films with both high transparency and high conductivity.