In a paper published in the journal Nanomaterials, researchers focused on improving the power conversion efficiency (PCE) and operational stability of perovskite solar cells (PSCs) by modifying electron and hole transport layers with nanomaterials. They highlighted the unique quantum properties of colloidal quantum dots (QDs), which help reduce charge recombination. Despite challenges in preparing QDs with precise sizes, advances in laser technology, particularly pulsed laser irradiation in colloids (PLIC), offered promising solutions. The study also discussed the potential and challenges of QD-based PSCs.
Study: A Review on Pulsed Laser Preparation of Quantum Dots in Colloids for the Optimization of Perovskite Solar Cells: Advantages, Challenges, and Prospects. Image Credit: Van Pympk/Shutterstock.com
Related Work
Past work has shown that PSCs benefit from nanomaterials like QDs to enhance PCE and operational stability by modifying structural defects in perovskite layers. PLIC has been identified as a promising method for preparing QDs with tunable size and purity. Studies demonstrate that PLIC-prepared QDs can passivate defects, improve charge carrier dynamics, and reduce recombination rates.
Enhancing PSC Performance
Preparing QDs using PLIC methods is a key area of research for PSC optimization. Three main types of PLIC—pulsed laser ablation in colloids (PLAC), pulsed laser fragmentation in colloids (PLFC), and pulsed laser melting in colloids (PLMC)—have been developed for the fabrication of nanomaterials. These methods control QD size and morphology by adjusting laser fluence and beam characteristics. Colloidal QDs enhance PSC performance by repairing defects in electron transport layers (ETL) or acting as the ETL.
By forming heterojunctions with perovskite materials, QDs improve photocarrier diffusion and energy efficiency, boosting PSCs' PCE. The heteroepitaxy of lead sulfide (PbS) QDs with methylammonium lead iodide (MAPbI3) perovskite, as demonstrated by Sargent's group, exemplifies the potential of QDs to optimize PSC performance.
QD Boost PSCs
Using pulsed laser-prepared QDs has emerged as a promising method to enhance the performance and stability of PSCs. By addressing structural defects in the perovskite layer, QDs can improve charge carrier transport, leveraging their unique quantum effects.
One key advancement is the development of liquid metal QDs, like the Galinstan QDs (eutectic alloys of gallium (Ga), indium (In), and tin (Sn)), which repair defects in PSCs, achieving a peak PCE of 21.32%. These QDs, prepared using pulsed laser irradiation in liquids, can fill defects in the ETL and perovskite interfaces, enhancing device efficiency.
In addition to liquid metal QDs, carbon QDs have been utilized to optimize PSCs due to their lower cost and excellent electrical conductivity. For instance, anti-solvent carbon QDs (ASCQDs) have been shown to passivate grain boundaries in the perovskite layer, improving PCE by reducing non-radiative recombination. ASCQDs achieved a PCE of 14.95%, while another method using electrochemically active CQD (EACQDs) improved PCE by 23.81%, reaching a peak of 16.43%.
Semiconductor QDs, such as tungsten sulfide (WS2) QDs, have also been explored. These QDs were synthesized via pulsed laser irradiation and used to modify perovskite films, reducing defect density and improving PCE. The innovative use of these QDs, including liquid metal, carbon, and semiconductor variants, demonstrates their potential in optimizing PSC performance through defect passivation and improved material properties.
QD Strategies for PSC Optimization
QD modification has emerged as a key strategy for enhancing the PCE of PSCs. PLIC allows for precise control over QD size and purity, making it an effective approach for defect passivation and charge carrier transport. These QDs, by filling structural defects in the perovskite layer, contribute to improved material compactness and charge mobility. Alongside QD modification, other strategies, such as developing chemical ligands and novel structures, further optimize PSC performance.
Inverted PSCs have recently achieved a certified PCE of 26.54%, demonstrating improvements over conventional "n-i-p" structures. Innovations like self-assembled molecules (SAMs) and passivation strategies enhance the hole transport layer (HTL), reducing interfacial losses.
One breakthrough involves co-assembling carboxylic acid functionalized aromatic compounds with SAMs, which reduces agglomeration and improves interfacial properties. Additionally, emerging studies suggest that pulsed laser-fabricated QDs could further enhance HTL properties, offering a promising avenue for future research.
Various structural and chemical engineering approaches also offer potential for PSC optimization. Chemical ligand and ion engineering can enhance perovskite crystallization and improve interface compactness, while new structural designs, such as 2D/3D perovskite heterojunctions, show great promise.
These innovations have led to significant gains in PCE, with some PSCs achieving over 25% efficiency and stability. The commercialization of PSCs is accelerating, with flexible, printable, and semi-transparent modules being developed for industrial applications.
Conclusion
To sum up, the review emphasized the potential of colloidal QDs in PSCs for improving sunlight absorption and charge transport. It highlighted the advantages of PLIC in preparing and purifying QDs effectively. The challenges of small production yields were noted, but advancements in pulsed laser manufacturing were seen as a solution. It provided insights into optimizing perovskite layers through novel structures and ligand/ion engineering for future developments.
Journal Reference
Sun, L., et al. (2023). A Review on Pulsed Laser Preparation of Quantum Dots in Colloids for the Optimization of Perovskite Solar Cells: Advantages, Challenges, and Prospects. Nanomaterials, 14:19, 1550. DOI:10.3390/nano14191550, https://www.mdpi.com/2079-4991/14/19/1550
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