Ultrafine ZnO quantum dot-modified TiO2 composite photocatalysts: the role of the quantum size effect in heterojunction-enhanced photocatalytic hydrogen evolution

The role of exciton–phonon coupling in light emission in cesium lead bromide (CsPbBr3) nanosheets is investigated with combined photoluminescence spectroscopy and the multimode Brownian oscillator ...

Anomalous Temperature-Dependent Exciton–Phonon Coupling in Cesium Lead Bromide Perovskite Nanosheets

The temperature dependence of the photoluminescence (PL) transitions associated with various excitons and their phonon replicas in high-purity bulk ZnO has been studied at temperatures from 12 K to above room temperature (320 K). Several strong PL emission lines associated with LO phonon replicas of free and bound excitons are clearly observed. The room temperature PL spectrum is dominated by the phonon replicas of the free exciton transition with the maximum at the first LO phonon replica. The results explain the discrepancy between the transition energy of free exciton determined by reflection measurement and the peak position obtained by the PL measurement.

https://absimage.aps.org/image/MAR05/MWS_MAR05-2004-001046.pdf

Nature of Room-temperature Photoluminescence in ZnO

Understanding of ultrafast carrier dynamics in InP/ZnS colloidal quantum dots (QDs) is essential for their optoelectronic applications. In this paper, we have successfully fabricated high-quality I...

Ultrafast Charge Carrier Dynamics and Nonlinear Optical Absorption of InP/ZnS Core–Shell Colloidal Quantum Dots

We report the occurrence of morphology-induced variation in the phonon properties of a poly(vinylpyrrolidone)-capped ZnS semiconductor. ZnS micro- and nanostructures such as microparticles, nanoparticles, nanorods (NRs), and nanowires (NWs) were synthesized through a single-step hydrothermal method at low temperature. Structural, morphological, and compositional analyses were performed using powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectra (EDS), and high-resolution transmission electron micrographic techniques. Moreover, morphology of the prepared samples was confirmed from off-resonant Raman studies. A strong first and higher orders of longitudinal optical (LO) phonon and weak fundamental and higher orders of transverse optical features were seen from UV Raman scattering. The electron–phonon coupling as a function of morphological changes of the nanostructures was analyzed by studying the differences in LO phonon linewidths among the samples. The dominance...

Resonant and Off-Resonant Phonon Properties of Wurtzite ZnS: Effect of Morphology on Fröhlich Coupling and Phonon Lifetime

ZnO quantum dots (QDs) embedded in an amorphous SiO2 matrix were examined in depth by using variable-temperature photoluminescence (PL) and optical reflectance spectroscopies. Compared with ZnO bulk crystals, ZnO quantum dots with an average size of 4 nm exhibit a strong quantum confinement effect, evidenced by a large blue shift in both PL and reflectance peaks of excitons. More interestingly, a remarkably reduced long-range Frohlich interaction was revealed in ZnO QDs. These fascinating effects may make ZnO QDs a very appealing system in the fields of optoelectronics and others.

JQ（宁吉强） Ning

Papers

Strong quantum confinement effect and reduced Fröhlich exciton–phonon coupling in ZnO quantum dots embedded inside a SiO2 matrix