Recombination processes in CuInS2/ZnS nanocrystals during steady-state photoluminescence

Abstract

We report on temperature-and excitation-power-dependent photoluminescence (PL) study of CuInS 2 /ZnS nanocrystals dispersed on a SiO 2 /Si substrate with a confocal micro-PL system. With increasing the excitation power at 22 K and room temperature, the PL spectra are blue-shifted because of the state filling. At low temperature, a small peak is observed at the low energy side of the spectrum, which could be due to the Förster resonance energy transfer between different nanocrystals. The integrated PL intensity increases sublinearly as a function of excitation power with a power factor of around 2/3, which demonstrates the Auger recombination dominated process in the nanocrystals, especially under the high excitation power.

High-Q Microcavity Enhanced Optical Properties of CuInS2/ZnS Colloidal Quantum Dots toward Non-Photodegradation

“…Since the photodegradation here is an irreversible process for QDs, the laser spot was moved to fresh places for each measurement when the excitation power is changed. It can be seen that the start peak position has a blueshift with increasing the excitation power because of the state filling as reported before [9]. At a low excitation power up to 7.5 µW, the peak position shows a quick blueshift firstly and then becomes stabilizing as a function of exposure time.…”

“…This might be caused by the enhancement of photooxidation, photobleaching, and the Auger effect with increasing pumping power. 9 With a reduced lifetime of the QDs, the fast Auger process (around 100 ps) could also be suppressed, resulting in an increased biexciton emission in the QDs. 45 This needs to be confirmed with further measurement using ultrafast time-resolved PL measurement.…”

“…Comparing to the traditional II-VI colloidal quantum dots (QDs) [1][2][3][4][5], copper indium sulfide (CIS) QDs [6][7][8][9], also called nanocrystals, have been investigated intensively as an alternative for having less toxic materials such as cadmium or lead. Because of the large Stokes shift of about 300 meV [10] and the wide emission energy tunability [6], CIS QDs have been explored in many applications such as light-emitting diodes [6], photovoltaics [11], and bioimaging [12].…”

Richardson-Schottky transport mechanism in ZnS nanoparticles

“…Nanostructured inorganic semiconductors such as zinc sulfide (ZnS), 1,2 cadmium sulfide (CdS) 3,4 and colloidal zinc sulfide (Co x , Cu x , CuInS x ; Zn 1-x S) [5][6][7] have been extensively investigated during the last decade due to their unique characteristics and potential applications that cannot be achieved from conventional macroscopic materials. Optical absorbance, fluorescence and electrical conductivity of such nanostructures are significantly different from their corresponding bulk materials.…”

Gain enhanced Fano resonance in a coupled photonic crystal cavity-waveguide structure

“…By placing partially reflecting elements in the PhC waveguide, Fano type transmission line shape is achieved. Recently, gain materials such as quantum dots 20 21 , nanocrystals 22 and rare-earth ions 23 24 have been used as light-emitting centers to achieve single-photon sources, display devices and all-optical diodes, respectively. Additionally, lasers have been demonstrated with coupling these light sources to microcavities 25 26 .…”