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Band gap energy and surface defect on the nanostructure play an important role especially in determining the performance and properties of the optical based gas sensor. In this report, ZnO nanorods (ZNRs) with various growth concentrations were successfully synthesized using a facile wet chemical approach. The gas sensing performance of the ZNRs samples with different concentrations were tested toward the highly hazardous carbon monoxide (CO) gas at a concentration of 10 ppm operated at room temperature. It was found that the 40 mM ZNRs sample exhibited the highest response coupled with the shortest response time (123.3 ± 1.3 s) and recovery time (7.7 ± 0.3 s). The high response and accelerated sensing reaction were attributed to the band gap narrowing of the 40 mM ZNRs induced by the increase in oxygen vacancy related defect states, and it is directly proportional to the CO gas sensing activity. These defects acted as the oxygen trap sites which will promote the oxygen adsorption on the surface of ZNRs and enhanced its gas sensing capability. The ZNRs reported herein which exhibits a high sensitivity, fast and reversible response with rapid recovery have great potential to be used in toxic gas sensing applications at room temperature. [ABSTRACT FROM AUTHOR]

For nanoscale fabrication of organic photovoltaic device, the utilization of a hole extraction layer (HEL) is essential to prevent the wrong flow of charge carriers and overcome the Schottky barrier at electrode-polymer interface. In recent years, the degradation issue of PEDOT:PSS based device which arises from its acidic nature and extremely hygroscopic properties has prompted researchers to find an appropriate transition metal oxide as replacement. In current work, we introduced an entirely solution-processed substoichiometric vanadium oxide (V2Ox) as HEL in inverted polymer:fullerene based device. We demonstrated the efficiency of substoichiometric V2Ox layer in enhancing the device performance of inverted organic solar cells, with the PCE of the device increased from 1.91 to 2.89%. The V2Ox prepared herein was found to exhibit broad optical absorption, highly selective charge transporting properties and excellent film transparency. A robust correlation between the hole extraction nature and electronic band structure of V2Ox was also established in this work. [ABSTRACT FROM AUTHOR]

Hybrid ZnO nanostructure with controlled morphology have been proved to enhance the physical and chemical properties of the material and used as photodiode and sensor. In this paper, hybrid graphene-ZnO nanoflower and nanorods have been successfully synthesized via a seed mediated method with micropatterned ZnO nanoseed treated with multilayer graphene (MLG) in a hydrothermal process. In typical process, the ZnO nanoseeds with and without resists were spin coated with a multilayer graphene prior to the growth process. The treated seed was then used to grow the ZnO nanostructures in the growth solution that contained equimolar (0.04 M) of zinc nitrate hexahydrate and hexamethylenetetramine. The growth process was carried out inside an autoclave at temperature 70 °C. The growth time was 4 h. It was proved that the MLG treatment on micropatterning substrate may induce new morphology formation of ZnO nanostructure. It is expected that the heteroepitaxy reaction occurred between the MLG and ZnO interface. This presence method can be used as an alternative approach to control the morphology of hybrid ZnO nanostructure growth. [ABSTRACT FROM AUTHOR]

One-dimensional ZnO nanorods (ZNRs) synthesized on fluorine-doped tin oxide (FTO) glass by hydrothermal method were modified with cadmium sulfide quantum dots (CdS QDs) as an electron transport layer (ETL) in order to enhance the photovoltaic performance of inverted organic solar cell (IOSC). In present study, CdS QDs were deposited on ZNRs using a Successive Ionic Layer Adsorption and Reaction method (SILAR) method. In typical procedures, IOSCs were fabricated by spin-coating the P3HT:PC61BM photoactive layer onto the as-prepared ZNRs/CdS QDs. The results of current-voltage (I-V) measurement under illumination shows that the FTO/ZNRs/CdS QDs/P3HT:PC61BM/PEDOT: PSS/Ag IOSC achieved a higher power conversion efficiency (4.06 %) in comparison to FTO/ZNRs/P3HT:PC61BM/PEDOT: PSS/Ag (3.6 %). Our findings suggest that the improved open circuit voltage (Voc) and short circuit current density (Jsc) of ZNRs/CdS QDs devices could be attributed to enhanced electron selectivity and reduced interfacial charge carrier recombination between ZNRs and P3HT:PC61BM after the deposition of CdS QDs. The CdS QDs sensitized ZNRs reported herein exhibit great potential for advanced optoelectronic application. [ABSTRACT FROM AUTHOR]