Probing defects and their implications in pH-controlled ZnO QDs: a theory-aided experimental investigation

Abstract

ZnO QDs at different pH (8–12) concentrations were prepared using the hydrothermal method. The crystallite size decreases with the increase of pH concentration in the range of ~ 8 nm to ~ 4 nm. FESEM studies confirm the agglomerated highly dense homogeneous QDs. Optical studies reveal decrement in optical band gap with highly confined QDs. The detailed study of photoluminescence of ZnO QDs signifies the presence of the defect between the conduction band and the valence band. Drastic blue shift and enhancement in oxygen vacancies are obtained with more confined QDs as pH increases. The electrical conductance improves considerably and may be due to the increase in oxygen-related defects with increasing pH. With increasing pH the UV sensitivity increases but for all visible light decreases. Using density functional theory structural, electronic and electron localization functions have been determined. Hence a co-related study of experimental and theoretical work of prepared QDs is investigated. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.