Band Gap Bowing at Nanoscale: Investigation of CdS_xSe_(1-x) Alloy Quantum Dots through Cyclic Voltammetry and Density Functional Theory

摘要

The band gap bowing effect in oleic acid-stabilized CdS_xSe_(1-x) alloy quantum dots (Qjdots) with varying composition has been studied experimentally by means of cyclic voltammetry and theoretically using density functional theory based calculations. Distinct cathodic and anodic peaks observed in the cyclic voltammograms of diffusing quantum dots alloy are attributed to the respective conduction and valence band edges. The quasi-particle gap values determined from voltammetric measurements are compared with interband transition peaks in UV—vis and PL spectra. Electronic structure for alloy Q;dots is determined computationally with projector augmented wave method for a particular size of dots. The band gap bowing is observed predominantly in the conduction band states. The bowing parameter determined experimentally (0.45 eV) has been found to be in good agreement with the one estimated from DFT (0,43 eV).