The ink engineering approach increases efficiency and reduces the cost of photovoltaics based on quantum points

Colloidal quantum points (CQD) are tiny semiconductive particles which are only a few size nanometers, which are synthesized in a liquid solution (ie colloid). These monocrystalline particles, created by decomposing bulk materials via chemical and physical processes, proved to be promising for the development of photovoltaic technologies (PV).

PV based on quantum points could have various advantages, including an adjustable prohibited strip, greater flexibility and solution treatment. However, solar cells based on quantum points developed so far have proven to have significant limits, in particular lower efficiency than conventional silicon -based cells and high manufacturing costs, due to the expensive processes necessary to synthesize CQD drivers.

Researchers from the University of Soochow in China, the University of Electro-Communizations in Japan and other institutes around the world have recently introduced a new method that could potentially help improve the efficiency of photovoltaics based on quantum points, while reducing their manufacturing costs. Their proposed approach, described in an article published in Nature energyinvolves engineering of CQD inks of lead sulfide (PBS) used to print films for solar cells.

“When people discuss colloidal quantum points (CQD), the first thing that comes to mind is their quantum properties dependent on extremely attractive size, as well as compatibility with manufacturing methods based on low-cost solutions, which open fascinating possibilities for next generation semiconductors, in particular printable solar cells and optoelectronic devices,”

“However, these potential applications are often overshadowed by complex and expensive synthesis and manufacturing processes necessary to produce CQD drivers.”

The sophisticated and expensive processes currently used to produce CQD drivers films reach a limited efficiency, the costs of the active layers CQD ranging from $ 0.25 to $ 0.84 / WP, which are too high for their marketing. In addition, existing processes offer limited control over the quality of materials and therefore resulting solar cells.

“Before our work, the CQD solar modules exceeding 10 cm² have only obtained approximately 1% power conversion efficiency (PCE), a striking contrast with the PCE by more than 12% of laboratory scale devices (0.04 cm²),” said Liu. “This efficiency gap, combined with expensive and complex methods involving hot injection and an exchange of ligands, made CQD photovoltaics almost impractical. The efficiency gap, as well as costly methods, made CQD photovoltaics impractical.”

The main objective of the recent work in Liu and its colleagues was to facilitate the future development of PVS on the basis of quantum points, allowing low -cost production of large -scale and effective solar cells. In an effort to achieve this objective, they have introduced a new ink engineering approach which could support the production of CQD films.

“To make films with quantum dots of large region, these particles must be uniformly and closely stacked while retaining their individual states to preserve quantum effects,” said Liu. “Any inconsistency of size or stack can lead to a loss of energy, a negative impact on the performance of semiconductors. This has a delicate balance between the stack of quantum points and the design of the ligand.”

Conventional approaches to creating CQDs are based on hot injection techniques to produce quantum points wrapped in long -chain insulating ligands, followed by a shorter exchange of shorter chains that stimulates the conductivity of a film. These approaches are both costly and complex, so they are difficult to reproduce on a large scale.

“Ligand exchange processes increase both the complexity and the costs of materials, while causing aggregation and morphological defects, which makes uniformity in large areas difficult,” said Liu. “On the other hand, our approach uses a direct synthesis technique (DS) to prepare CQD inks.”

The new ink engineering method designed by Liu and its colleagues allows the synthesis of CQD wearing ions directly in a polar solvent, thus eliminating the need for complex ligand exchange processes. Using their approach, the researchers were able to print CQD films, drivers closely wrapped in a single step.

“To minimize aggregation and fusion, we control the chemical environment of ink, using an engineering strategy of solution chemistry (SCE) for precise adjustment of ionic configurations and functionalities,” said Liu. “Simplified quantum points technology and improved ink stability lead to stable CQD inks with fewer defects, allowing large -scale manufacturing of thin movies with quantum points and photovoltaic devices, all at a cost less than $ 0.06 / WP.”

Shi, Liu and their colleagues tested their approach proposed in a series of tests and showed that this led to the production of very stable quantum points. In addition, they discovered a link between interactions with quantum points dominated by the surface and the irreversible quantum points and the defects present in printed CQD films, as well as the performance of large -surface solar cells based on these films.

“Our efforts have led to the creation of the first CQD solar module in large region with an effectiveness of certified power conversion (PCE) exceeding 10%, marking a significant step towards the marketing of photovoltaics based on the CQD,” said Liu.

“In addition, we have obtained a very effective small solar cell with a 13.40%PCE, establishing a new reference for CQD technology. These advances are crucial because they raise the challenges of scalability and costs which have long limited the general use of CQD solar cells.”

This recent study could soon contribute to the development of low -cost CQD solar cells, with large surface and very efficient and other optorelectronic devices, such as sensors or tools near infrared for space exploration.

As part of their next studies, Liu and his colleagues plan to further refine the inks produced using their approach, as this could lead to solar cells with even better efficiency, while extending their possible real applications.

“We will explore the adaptation of technology for various quantum points, including low toxicity variants and flexible electronics,” added Liu. “In addition, we will study their use in fields such as short -wave infrared imaging (SWIR) – Critical components to advance affordable AI technologies such as autonomous vehicles, smart robots and industrial automation.

“In the end, our objective is to extend this technology for commercial production, reducing both costs and the environmental impact of quantum electronics.”

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