Role of Trioctylphosphine in the Synthesis of Quantum Dots: A Modulator of Nucleation, Growth, and Solubility

Abstract

Trioctylphosphine (TOP) is widely used in the synthetic process of colloidal quantum dots (QDs). However, its role has not been fully elucidated yet. Herein, the role of TOP was revealed by kinetic studies with spectroscopic methods. It was found that TOP suppressed the growth rate but increased the solubility; hence, it modulated QDs by controlling both. The extent of impact from TOP varied in the length of acids that was used in QD synthesis. In general, the impact from TOP to QDs synthesized by short acids was mainly the suppressing effect because shorter aliphatic acids had a higher diffusion rate, and they might suffer from TOP a lot. On the contrary, longer aliphatic acids diffused intrinsically slowly, so the reaction rate was rarely influenced by TOP, but the solubility was supposed to be considered at this time. This difference also led to the optimal amount of TOP used in the synthesis. These results pointed out that both the growth rate and solubility were time-dependent and should be considered to obtain high-quality QDs. In addition, the initial nucleation procedure was also seemingly suppressed by TOP. This work not only shed light on the underlying role of TOP and convinced the controllable synthesis of QDs but also provided a method to investigate the behavior of QD growth by considering several conditions synergistically and dynamically.

Ligand Exchange of Quantum Dots: A Thermodynamic Perspective

“…QDs are composed of an inorganic core and organic surface ligands − (Figure ). The inorganic core of QDs has a decisive impact on the fundamental properties of QDs, such as energy level position and bandgap. , Organic surface ligands, as one of the important components of QDs are bound to the surface of QDs and are responsible for controlling the synthetic process, adjusting their electronic properties, and mediating their interactions with the surrounding. − Surface ligands exist in three forms including chemical adsorption, physical adsorption, and free state. − In addition, the organic ligands can be classified into X-, L-, and Z-type ligands according to the number of electrons they donate (Figure ). ,− …”

Understanding Hot Injection Quantum Dot Synthesis Outcomes Using Automated High-Throughput Experiment Platforms and Machine Learning

“…Semiconductor quantum dots (QDs) offer the potential to design nanomaterials with widely tunable optoelectronic properties by control over size, shape, phase, and composition. , They demonstrate promise in a wide range of applications such as catalysis, coatings, imaging, sensing, displays, photovoltaics, and more. ,− In many of these applications, tight control over QD properties (shape, size distribution, composition, and heterostructures) is critical as these parameters determine key optical and electronic properties including absorption and emission. Several studies have sought to understand QD synthesis by uncovering mechanisms of their formation (reaction, nucleation, and growth steps) and by demonstrating methods to tune synthesis parameters to achieve specific QD properties. − …”