Effect of Different Sources of Cu‐dopant on Material Properties of ZnO Nanorods Grown on a GZO Film by Chemical Bath Deposition for Photovoltaic Applications

Abstract

The controlled incorporation of dopants like copper into ZnO nanorods (ZNRs) grown by chemical bath deposition (CBD) is still challenging despite its critical importance for the development of optoelectronic devices such as dye‐sensitized solar cells and piezoelectric devices. This study investigates the effects of different sources of copper precursor on the material properties of ZNRs during the CBD of ZNRs grown on GZO seed layers. The findings offer deep insight into the physicochemical processes at work during the CBD of ZNRs following the addition of different copper precursors, including copper (II) nitrate‐doped ZNRs (CNZNRs), copper (II) sulfate‐doped ZNRs (CSZNRs), and copper (II) chloride‐doped ZNRs (CCZNRs). The study also explores how varied copper sources affect copper incorporation into ZNRs, extending beyond the electrostatic forces typically driving the incorporation of dopants like Al and Ga. X‐ray diffraction, scanning electron microscopy (SEM), UV–vis, and photoluminescence (PL) were used to characterize the properties of pure‐ZNRs, CNZNRs, CSZNRs, and CCZNRs. Structural investigations confirmed that all grown samples had wurtzite hexagonal structures and that the c ‐axis was the sole orientation of growth. The CNZNRs sample presented the highest crystallinity and lowest strain. SEM images showed deformed morphology and less fine nanorods for the CCZNRs sample, but well‐formed and aligned nanorods for ZNRs and CNZNRs counterparts. Similarly, good luminescence and a low density of deep‐level defects, as marked by high PL emission intensity ratios, were observed for ZNRs, CNZNRs, and CSZNRs in that order, but diminished luminescence was noted in the case of the CCZNRs sample. The optical analysis displayed the highest percentage transmittance for CNZNRs and a redshift in the absorption edges and peaks with variation in the Cu‐dopant precursors. The bandgap values were observed to increase from 3.30 eV (CNZNRs) to 3.39 eV (CCZNRs).