Photoluminescence of spray pyrolysis deposited ZnO nanorods
- PDF / 484,181 Bytes
- 7 Pages / 595.28 x 793.7 pts Page_size
- 68 Downloads / 270 Views
NANO EXPRESS
Open Access
Photoluminescence of spray pyrolysis deposited ZnO nanorods Erki Kärber1, Taavi Raadik1, Tatjana Dedova1, Jüri Krustok1, Arvo Mere1, Valdek Mikli2 and Malle Krunks1*
Abstract Photoluminescence of highly structured ZnO layers comprising well-shaped hexagonal rods is presented. The ZnO rods (length 500-1,000 nm, diameter 100-300 nm) were grown in air onto a preheated soda-lime glass (SGL) or ITO/SGL substrate by low-cost chemical spray pyrolysis method using zinc chloride precursor solutions and growth temperatures in the range of 450-550°C. We report the effect of the variation in deposition parameters (substrate type, growth temperature, spray rate, solvent type) on the photoluminescence properties of the spray-deposited ZnO nanorods. A dominant near band edge (NBE) emission is observed at 300 K and at 10 K. High-resolution photoluminescence measurements at 10 K reveal fine structure of the NBE band with the dominant peaks related to the bound exciton transitions. It is found that all studied technological parameters affect the excitonic photoluminescence in ZnO nanorods. PACS: 78.55.Et, 81.15.Rs, 61.46.Km Introduction ZnO is a semiconductor material for various photonic and electrical applications. ZnO shows a unique set of physical and chemical properties, such as a wide band gap (3.37 eV), large exciton binding energy (60 meV) at room temperature, radiation hardness [1], piezoelectricity and photoelasticity [2] and surface chemistry sensitive to environment. Zinc oxide nanostructured layer comprizing nanorods, further denoted as ZnO nanorod layer (ZnONRL), is a material with large effective surface area, suitable for short-wavelength devices, such as ultraviolet (UV) light-emitting diodes (LED) [3,4], UV nanolaser arrays [5], UV photodetectors [6], field emitters [7], UV protectors-filters [8], and chemical sensors [9,10]. As a passive layer with light-trapping properties, ZnONRL can be used as an antireflection coating on silicon solar cells [11], surface-enhancing window layer in the second generation solar cells with extremely thin inorganic absorber layer (ETA) [12] or with dye-sensitized solar cells (DSSC) [13]. The chemical spray pyrolysis (CSP)-deposited ZnONRL was used in ETA solar cells showing energy conversion efficiency of 4.2% [14].
* Correspondence: [email protected] 1 Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia Full list of author information is available at the end of the article
For many of such devices, a large-scale, low-cost fabrication of high optical and crystalline quality ZnO is desirable. Low-temperature chemical synthesis methods can provide large scale and low-cost fabrication. Photoluminescence (PL) is a very sensitive and an effective method to identify the dominant recombination mechanism and defects in materials. However, according to PL study, the as-deposited ZnONRL grown via a lowtemperature wet-chemical methods (chemical bath, electrodeposition, hydrothermal growth) do not show a high e
Data Loading...
