Eosin Y-adsorbing ZnO thin films were prepared on substrates by electroless deposition from aqueous solutions containing zinc nitrate, dimethylamine borane, and eosin Y. The concentration of eosin Y in the solution changed the structure of the deposited ZnO particles on the substrate. In the absence of eosin Y in the solution, the ZnO crystals preferred to grow in the c-axis direction. In the presence of eosin Yin the solution, the orientation of the ZnO was in the a-axis direction. As the eosin Y concentration increased, the size of the ZnO crystallites decreased and they became aggregated due to a strong interaction between the eosin Y and the (0002) plane of the ZnO, and consequently, the film resistance increased due to their boundary. The electron injection efficiency increased due to the strong interaction although the electron transfer efficiency decreased. The ZnO crystallite size, eosin Y amount, and their interaction increased the energy conversion efficiency. (C) 2016 Published by Elsevier B.V.