Bigger is not faster
Meng Zhu, Benoit Mahler, Julien Houel, Florian Kulzer, Gilles Ledoux et Christophe Dujardin (Luminescence), in collaboration with a colleague from Moscow, published a paper entitled "Perspectives for CdSe/CdS spherical quantum wells as rapid-response nano-scintillators" in the journal Nanoscale.
Inorganic scintillators are materials that emit light under ionizing radiation and therefore play an important role for its detection in a wide range of applications. In particular, ultra-fast emitters are crucial for the implementation of very precise time-of-flight detection systems, which are needed to meet the 10-picosecond challenge. In this context, nanoparticles of direct bandgap semiconductors are among the promising candidates.
In this contribution, we explore the effect of shell thickness on the time response of CdS/CdSe/CdS spherical-quantum-well nanoscintillators. Our combination of modelling and time-resolved spectroscopy under X-ray excitation demonstrates that, surprisingly, there is no benefit to using larger particles in order to favor multiexciton generation. On the contrary, Auger quenching does in fact compensate the higher number of excitons per particle, while the larger particle sizes lead to defects that slow down the overall timing performance; these mechanistic insights have important implications for guiding future development of semiconductor nanopaticle-based scintillators.
In this contribution, we explore the effect of shell thickness on the time response of CdS/CdSe/CdS spherical-quantum-well nanoscintillators. Our combination of modelling and time-resolved spectroscopy under X-ray excitation demonstrates that, surprisingly, there is no benefit to using larger particles in order to favor multiexciton generation. On the contrary, Auger quenching does in fact compensate the higher number of excitons per particle, while the larger particle sizes lead to defects that slow down the overall timing performance; these mechanistic insights have important implications for guiding future development of semiconductor nanopaticle-based scintillators.
