Low-temperature photoluminescence spectroscopy of single core/shell nanoplatelets

With promising applications in lasing, light-emitting diodes, as well as quantum photonics, semiconducting nanoplatelets (NPLs) with atomically controlled thickness and giant oscillator strength has attracted considerable interest in the past few years. Our previous studies¹ have revealed that with excitons in NPLs being strongly confined in the thickness direction, an increase in their lateral size and a weakening in the in-plane confinement has complex effects on their photon emission statistics and carrier dynamics. These properties are unique to NPLs due to their quasi-two-dimensional structures.

While room temperature studies of single NPLs provide valuable information, the spectrum is broadened by carrier-phonon interactions, making the assignment of optical transitions and the related electronic structures challenging. Here, we perform single NPL spectroscopic measurements at cryogenic temperatures. Spectral linewidth and diffusion are investigated systematically. In addition, we observe rich spectral fine structures from the NPLs. These results will shed new light on the intrinsic electronic structures of the NPLs, and help understand the origin of the much debated side emission peak observed in ensemble measurements.
1. X. Ma et al. ACS Nano, 2017, 11, 9119 – 9127