Effect of charging on CdSe/CdS dot-in-rods single-photon emission

Abstract

The photon statistics of CdSe/CdS dot-in-rods nanocrystals is studied with a method involving post-selection of the photon detection events based on the photoluminescence count rate. We show that flickering between two states needs to be taken into account to interpret the single-photon emission properties. With post-selection we are able to identify two emitting states: the exciton and the charged exciton (trion), characterized by different lifetimes and different second order correlation functions. Measurements of the second order autocorrelation function at zero delay with postselection shows a degradation of the single photon emission for CdSe/CdS dot-in-rods in a charged state that we explain by deriving the neutral and charged biexciton quantum yields.

CdSe/CdS Dot‐in‐Rods Nanocrystals Fast Blinking Dynamics.

“…[24] The bin time is Dt = 1 ms. This histogram reveals the presence of two emission peaks as expected for these emitters [25] for an excitation under saturation. The histogram of emission for a PL timetrace computed with a Dt = 150 ms bin time is also shown in Figure 1b right.…”

“…The corresponding histogram of emission is shown in Figure 1b left. Indeed, DRs with a thick shell such as DR2.1 have a reduced blinking between a bright and a grey state, as demonstrated using time resolved decay measurements in one of our previous work, [25] corresponding respectively to the radiative recombination of an exciton and a negative trion [11,13] with a lower emission rate. This histogram reveals the presence of two emission peaks as expected for these emitters [25] for an excitation under saturation.…”

“…Also it sometimes shows long dark periods of some seconds, while the bright periods are as previously always limited to a maximum of a few hundreds of microseconds. [25,13,14] The intensity correlation function was computed for each DR and fitted with Eq. The corresponding g (2) has characteristics similar to the other DRs correlation functions at short timescales ( < 10 ms).…”

Optical trapping of nanoparticles by full solid-angle focusing

“…For delays outside the central anti-bunching dip, the g (2) functions are larger than one. For the DRs this effect is attributed to blinking stemming from the presence of a charged state [32]. At large delays, the measured g (2) (τ ) approaches unity (not shown in Fig.…”

Exciton Fine Structure of CdSe/CdS Nanocrystals Determined by Polarization Microscopy at Room Temperature

“…They display a strongly reduced emission intermittency (reduced blinking) when synthesized with thick CdS shells, 6 and with a well adjusted geometry they have also be shown to be nearly perfect single photon emitters. 6,27 The situation for DRs is however less clear than for the nanorods mentioned above due to their more complex geometry. In fact, as reported in Ref.…”