Facile synthesis of composition-tuned ZnO/Zn x Cd1-x Se nanowires for photovoltaic applications

Abstract

ZnO/ZnxCd1-xSe coaxial nanowires (NWs) have been successfully synthesized by combining chemical vapor deposition with a facile alternant physical deposition method. The shell composition x can be precisely tuned in the whole region (0 ≤ x ≤ 1) by adjusting growth time ratio of ZnSe to CdSe. As a result, the effective bandgaps of coaxial nanowires were conveniently modified from 1.85 eV to 2.58 eV, almost covering the entire visible spectrum. It was also found that annealing treatment was in favor of forming the mixed crystal and improving crystal quality. An optimal temperature of 350°C was obtained according to our experimental results. Additionally, time resolved photo-luminescence spectra revealed the longest carrier lifetime in ZnO/CdSe coaxial nanowires. As a result, the ZnO/CdSe nanowire cell acquired the maximal conversion efficiency of 2.01%. This work shall pave a way towards facile synthesis of ternary alloys for photovoltaic applications.

Engineering Charge Transfer Characteristics in Hierarchical Cu2S QDs @ ZnO Nanoneedles with p–n Heterojunctions: Towards Highly Efficient and Recyclable Photocatalysts

“…Metals doping (such as gold, silver, rhodium, or platinum) [22,23], metal ions doping (such as Bi or Al) [24], and nitrogen doping [25] are the most used techniques to give rise to visible light activity of the semiconductor materials, to extend their light absorption ability from UV to visible range and to feature good electron transport. Beyond that, heterojunctions, which can effectively capture the photo-generated charge carriers to improve the charge separation efficiency, decrease the surface reaction over potential, enhance apparent quantum efficiencies and provide active sites for surface redox reaction at two different reaction sites, are believed to be essential to achieving highly efficient photocatalytic performances [26,27,28,29,30,31,32,33,34,35,36,37]. Recently, semiconductor heterojunctions composed of ZnO and other metal sulfides or oxides have also been extensively studied, for example combining ZnO with Cu 2 O, CdS, SnO 2 , MoO 3, and TiO 2 semiconductor materials [1,2,32,33,38,39,40].…”

“…Beyond that, heterojunctions, which can effectively capture the photo-generated charge carriers to improve the charge separation efficiency, decrease the surface reaction over potential, enhance apparent quantum efficiencies and provide active sites for surface redox reaction at two different reaction sites, are believed to be essential to achieving highly efficient photocatalytic performances [26,27,28,29,30,31,32,33,34,35,36,37]. Recently, semiconductor heterojunctions composed of ZnO and other metal sulfides or oxides have also been extensively studied, for example combining ZnO with Cu 2 O, CdS, SnO 2 , MoO 3, and TiO 2 semiconductor materials [1,2,32,33,38,39,40]. Aforementioned results demonstrate that the composites developed by coupling different semiconductor materials could exhibit collective and enhanced property by reciprocal transfer of electrons and holes from one semiconductor to the other under irradiation and, consequently, realizing a higher photocatalytic activity [41,42,43].…”

Effects of Vacuum Annealing on the Conduction Characteristics of ZnO Nanosheets

“…ZnO nanomaterials have received much attention over the past 15 years due to their novel properties including being a wide band gap (3.37 eV) piezoelectric material with a large exciton binding energy of 60 meV [ 1 , 2 ]. ZnO nanomaterials have many potential applications including antimicrobial bio-films [ 3 ], microelectronics [ 4 ], mechanical energy harvesting [ 5 ], field emitters [ 6 ], ultra violet lasers [ 7 ], photovoltaics [ 8 ] and other optoelectronic devices [ 9 ]. Polycrystalline ZnO nanosheets are a relatively new form of nanostructure and have demonstrated promising potential for practical applications such as gas-sensing devices and dye sensitised solar cells due to their high surface area to volume ratio [ 10 , 11 ].…”

Gradient engineered light absorption layer for enhanced carrier separation efficiency in perovskite solar cells

“…For instance, Wei Ruan1 et al fabricated MAPbI3/MAPb(IxBr1-x)3 heterostructure with a type-II band structure and achieved HTL-free PSCS 31 . In essence, it is an ideal approach to directly reduce recombination losses through the design of a gradient band structure in perovskite light absorption layer [32][33] , which supports the carrier separation as fast as possible. However, to the best of our knowledge, it has not been reported so far about the fabrication of perovskite materials with a gradient band structure.…”