title: Spectrally Resolved Photoluminescence Imaging of ZnO Nanocrystals at Single-Particle Levels.
abstract: The intrinsic spectral line widths of defect-related transitions in quantum-confined semiconductor nanocrystals are often difficult to estimate using ensemble measurements because the extent of inhomogeneous broadening due to particle size distributions is not known precisely. To address this problem, we performed spectrally resolved photoluminescence (PL) microscopy of individual ZnO NC by directly populating the defects states using low-energy laser excitation. The temporal evolution of PL intensities shows discrete blinking behaviors, suggesting that the NCs are detected near single-particle levels. The transition energies of individual NCs are found to fluctuate around their mean position (2.25 eV) by ∼0.130 eV, which is attributed to particle size distribution and defects densities associated with each NC. The spectral line width associated with defect emission envelope of ZnO NCs is found to be inherently broad (200-400 meV), which further establishes the presence of multiple closely spaced defect energy levels within every ZnO NC.
authors: Department of Chemistry and National Center for Photovoltaic Research and Education (NCPRE), Indian Institute of Technology Bombay, Mumbai 400076, India.
authors: Arunasish
authors: A
authors: Layek
authors: Department of Chemistry and National Center for Photovoltaic Research and Education (NCPRE), Indian Institute of Technology Bombay, Mumbai 400076, India.
authors: Suman
authors: S
authors: De
authors: Department of Chemistry and National Center for Photovoltaic Research and Education (NCPRE), Indian Institute of Technology Bombay, Mumbai 400076, India.
authors: Ruhi
authors: R
authors: Thorat
authors: Department of Chemistry and National Center for Photovoltaic Research and Education (NCPRE), Indian Institute of Technology Bombay, Mumbai 400076, India.
authors: Arindam
authors: A
authors: Chowdhury
keywords: defect energy; low-energy laser excitation; particle size distribution; spectral line width