We investigated the optical and optoelectronic properties of vertically aligned Al:ZnO nanorod arrays synthesized by the hydrothermal technique at a considerably low temperature on a sputtered Al:ZnO seed layer. The nanorod arrays maintained remarkable alignment along the c-axis over a large area. The seed layers and nanorod arrays showed various optical band gaps. Investigation of the optoelectronic properties of nanorod arrays on seed layer with revealed that the photocurrent is significantly reduced in nanorod arrays on a heterojunction due to multiple scattering phenomena associated with nanorod arrays. This research may open up venues for various optical and opto-electronic applications where highly aligned nanostructures are desired.