All chemicals used were analytical grade without further purification. The synthesis of ZnO nanorods consisted of two steps.The first step was the preparation of the ZnO–PVA seed layer. To prepare the seed layer,we used the procedure described by Heet al. [42] with several modifications. In this method, 0.1 mol/L of zinc chloride was dissolved in deionized (DI) water at 70 ◦C and vigorously stirred for 10 min. Similarly, 1.5 g of PVA was dissolved in 50mL DI water at 80 ◦C stirred for 30 min. The solutions were mixed together via high-speed stirring and placed on a hot plate at 70 ◦C for 2 h. The solution was transferred to a microwave oven for 15 min at 80 ◦C to facilitate complexation of zinc with PVA. At that stage, the pH of the solution was 4.0. To create the Zn(OH)2 complex with PVA polymer chains,ammonia solution was added to the mixture until the pH reached 8.3 and the solution became milky white. The PVA–Zn(OH)2 complex solution was then spin-coated on a silicon substrate {p-type, (1 1 1)} etched with 1:20 HF:DI water for