Comparative study of photoluminescence dynamics of CdSe quantum dots on glass and ITO

This study investigates the photoluminescence (PL) dynamics of CdSe quantum dots (QDs) on indium tin oxide (ITO) substrates under various excitation intensities to understand the impact of QD charging on PL. The analysis reveals that under low pump fluence, approximately 75% of the QDs in the assembly are negatively charged due to direct contact with the ITO substrate, resulting in a shortened average PL lifetime and weakened PL intensity. Under high pump fluence conditions, the charging percentage is further increased by the photo charging effect, leading to the undesirable depletion of the biexciton state through the accelerated non-radiative Auger process. The PL dynamic mechanism is analyzed to explain the absence of amplified spontaneous emission (ASE) in the QD on ITO samples. The findings of this study have potential implications for the development and optimization of QD-based devices, such as quantum dot light-emitting diodes (QLEDs) and quantum dot lasers, by providing insights into the detrimental effects of QD charging on device performance and suggesting strategies to mitigate these effects.