In a recent study published in Nanomaterials, researchers explored strategies to enhance the power conversion efficiency (PCE) and operational stability of perovskite solar cells (PSCs) by incorporating nanomaterials into the electron and hole transport layers.
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
The study in question emphasized the unique quantum properties of colloidal quantum dots (QDs), which play a critical role in minimizing charge recombination, a key factor in improving overall cell efficiency.
Despite the ongoing challenges in synthesizing QDs with precise size control, advancements in laser technology—specifically pulsed laser irradiation in colloids (PLIC)—have provided promising avenues for overcoming these obstacles. The study also delved into the potential and limitations of QD-based PSCs, highlighting both their emerging benefits and the technical hurdles that remain.
Related Work
Previous research has demonstrated that PSCs can significantly benefit from the integration of nanomaterials, such as QDs, to improve PCE and operational stability. These enhancements are achieved by addressing structural defects within the perovskite layers.
PLIC has emerged as a promising technique for synthesizing QDs with tunable size and high purity. Studies have shown that QDs prepared using PLIC can effectively passivate defects, enhance charge carrier dynamics, and lower recombination rates, contributing to better overall performance of PSCs.
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.
How do Quantum Dots Boost PSCs?
The use of pulsed laser-prepared QDs has emerged as a promising approach to improve both the performance and stability of PSCs. By addressing structural defects within the perovskite layer, these QDs enhance charge carrier transport through their unique quantum properties.
A significant advancement in this area is the development of liquid metal QDs, such as Galinstan QDs—eutectic alloys composed of gallium (Ga), indium (In), and tin (Sn). These QDs have been shown to repair defects in PSCs, achieving a peak PCE of 21.32 %. Synthesized using pulsed laser irradiation in liquids, these QDs effectively fill defects in both the ETL and perovskite interfaces, leading to improved device efficiency.
In addition to liquid metal QDs, carbon QDs offer a cost-effective solution with excellent electrical conductivity. For example, anti-solvent carbon QDs (ASCQDs) have demonstrated the ability to passivate grain boundaries within the perovskite layer, thereby reducing non-radiative recombination and improving PCE. ASCQDs have reached a PCE of 14.95 %, while another method involving electrochemically active carbon QDs (EACQDs) achieved a 23.81 % improvement in PCE, peaking at 16.43 %.
Semiconductor QDs, such as tungsten sulfide (WS2) QDs, have also been explored for their potential in PSCs. Synthesized through pulsed laser irradiation, these QDs have been utilized to modify perovskite films, reducing defect density and further enhancing PCE. The innovative application of these QDs—whether liquid metal, carbon, or semiconductor—underscores their potential to optimize PSC performance by passivating defects and enhancing 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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Article Revisions
- Oct 1 2024 - Revised sentence structure, word choice, punctuation, and clarity to improve readability and coherence.