Hydrothermal Synthesis of Vertically Aligned Cesium-Doped ZnO Nanorods for Solar Cell Applications

Single crystalline cesium-doped ZnO nanorods with homogeneous size and shape were hydrothermally grown on Cs–ZnO nucleated glass substrate. The effect of hydrothermal growth duration on the characteristics of Cs-doped ZnO nanorods was examined. The samples were analyzed by X-ray diffraction (XRD), energy dispersive X-ray analysis, scanning electron microscopy, and electrical conductivity, optical transmission and photoluminescence (PL) measurements. XRD analysis showed that Cs-doped ZnO nanorods are wurtzite single crystals and are grown preferentially along the c-axis. Elemental analysis confirmed the presence of 1 at.% of Cs, according to the composition of growth solution. Electrical conductivity of typical samples showed higher values for the 1 at.%-doped sample, which confirmed incorporation of the Cs dopant. The samples were optically transparent and showed two UV and visible PL peaks from which the former peak experienced a red shift and a pronounced increase in intensity with increasing growth time. The fabricated Cs-doped ZnO nanorods are suitable candidates for applications as excitonic solar cells due to their ease of fabrication, morphology control and optical properties.