Laser ablation has emerged as a versatile and controllable technique for producing high-quality semiconductor quantum dots (QDs), including silicon (Si), cadmium selenide (CdSe), and perovskite variants. Unlike chemical synthesis methods, laser ablation offers a solvent-free, high-purity approach that minimizes contamination while enabling precise control over particle size and quantum confinement effects. The process involves irradiating a bulk target material with a high-energy pulsed laser in a liquid or gaseous medium, leading to the ejection of material that condenses into nanoparticles. The absence of chemical precursors reduces the need for post-synthesis purification, making it advantageous for applications requiring high-purity QDs.

The size and optical properties of laser-ablated QDs are primarily determined by laser parameters such as wavelength, pulse duration, fluence, and repetition rate. Shorter wavelengths (e.g., UV lasers) typically produce smaller nanoparticles due to higher photon energy, which enhances material removal efficiency. Pulse durations in the nanosecond or femtosecond range influence particle size distribution, with shorter pulses reducing thermal diffusion and yielding narrower size distributions. Fluence, or energy density, directly affects ablation efficiency and particle size, where higher fluence can lead to larger aggregates if not optimized. Repetition rate influences productivity, with higher rates increasing yield but potentially causing heat accumulation that affects particle uniformity.

Quantum confinement effects in laser-ablated QDs are tightly linked to particle size, which is controlled by adjusting these laser parameters. For instance, CdSe QDs exhibit a tunable bandgap ranging from 1.7 eV to 2.5 eV as their size decreases from 7 nm to 2 nm due to quantum confinement. Similarly, silicon QDs, which are typically indirect bandgap materials, display visible photoluminescence when reduced below 5 nm, a phenomenon attributed to quantum confinement-induced direct transitions. Perovskite QDs, such as CsPbBr3, show sharp emission peaks with high photoluminescence quantum yields (PLQY) exceeding 80% when synthesized under optimized ablation conditions, rivaling chemically synthesized counterparts.

Surface passivation is critical during laser ablation to prevent defect formation and maintain optical stability. In situ passivation can be achieved by ablating the target in reactive media, such as organic solvents or ligands, which cap the QD surface as they form. For example, ablation of silicon in ethanol leads to ethoxy-terminated surfaces that reduce oxidation and enhance PLQY. Similarly, CdSe QDs ablated in oleic acid exhibit improved colloidal stability and reduced surface traps. Perovskite QDs benefit from ablation in polar solvents containing ammonium ligands, which passivate surface vacancies and suppress ion migration, a common issue in perovskite nanomaterials. Post-ablation treatments, such as ligand exchange or shell coating (e.g., ZnS on CdSe), further enhance stability and optical performance.

Compared to chemical synthesis, laser ablation offers distinct advantages and trade-offs. Chemical methods, such as hot-injection for CdSe QDs or sol-gel for perovskites, provide excellent size control and high PLQY but often require toxic precursors (e.g., CdO, TOP-Se) and generate hazardous waste. In contrast, laser ablation is greener, avoiding organic solvents and enabling the use of non-toxic raw materials. However, chemical synthesis typically achieves narrower size distributions (5–10% variability) compared to laser ablation (10–20%), which can affect color purity in display applications. Scalability remains a challenge for laser ablation, as throughput is limited by laser power and scanning systems, whereas chemical methods can be scaled to industrial volumes more readily.

Optical properties of laser-ablated QDs are competitive with chemically synthesized ones, particularly in terms of purity and defect density. For instance, laser-ablated perovskite QDs exhibit comparable PLQY (70–90%) to those made via ligand-assisted reprecipitation, with the added benefit of reduced batch-to-batch variability. Silicon QDs produced by ablation show superior stability against oxidation compared to those synthesized by electrochemical etching, making them suitable for long-term applications. CdSe QDs from laser ablation exhibit broader emission spectra but higher crystallinity, which benefits charge transport in solar cells.

Applications of laser-ablated QDs leverage their unique advantages. In displays, perovskite QDs stand out for their narrow emission and high color purity, enabling wide-gamut LEDs and backlighting. Laser ablation’s solvent-free process avoids contamination risks that can degrade display performance. For solar cells, silicon QDs produced by ablation enhance light absorption in tandem structures due to their tunable bandgap and minimal impurity scattering. In biological labeling, the absence of toxic residues in laser-ablated CdSe QDs makes them safer for live-cell imaging compared to chemically synthesized alternatives requiring cytotoxic capping agents.

In summary, laser ablation provides a clean, controllable route to semiconductor QDs with tunable quantum confinement and robust surface passivation. While challenges in scalability and size distribution persist, the technique’s advantages in purity and environmental compatibility make it ideal for high-performance applications in optoelectronics and biomedicine. Continued optimization of laser parameters and passivation strategies will further bridge the gap with chemical methods, unlocking new possibilities for QD-based technologies.